Microbiological and Geochemical Survey of CO2-Dominated Mofette and Mineral Waters of the Cheb Basin, Czech Republic

Abstract

The Cheb Basin (NW Bohemia, Czech Republic) is a shallow, neogene intracontinental basin. It is a non-volcanic region which features frequent earthquake swarms and large-scale diffuse degassing of mantle-derived CO2 at the surface that occurs in the form of CO2-rich mineral springs and wet and dry mofettes. So far, the influence of CO2 degassing onto the microbial communities has been studied for soil environments, but not for aquatic systems. We hypothesized, that deep-trenching CO2 conduits interconnect the subsurface with the surface. This admixture of deep thermal fluids should be reflected in geochemical parameters and in the microbial community compositions. In the present study four mineral water springs and two wet mofettes were investigated through an interdisciplinary survey. The waters were acidic and differed in terms of organic carbon and anion/cation concentrations. Element geochemical and isotope analyses of fluid components were used to verify the origin of the fluids. Prokaryotic communities were characterized through quantitative PCR and Illumina 16S rRNA gene sequencing. Putative chemolithotrophic, anaerobic and microaerophilic organisms connected to sulfur (e.g., Sulfuricurvum, Sulfurimonas) and iron (e.g., Gallionella, Sideroxydans) cycling shaped the core community. Additionally, CO2-influenced waters form an ecosystem containing many taxa that are usually found in marine or terrestrial subsurface ecosystems. Multivariate statistics highlighted the influence of environmental parameters such as pH, Fe2+ concentration and conductivity on species distribution. The hydrochemical and microbiological survey introduces a new perspective on mofettes. Our results support that mofettes are either analogs or rather windows into the deep biosphere and furthermore enable access to deeply buried paleo-sediments.

Thermoplasmatales and sulfur-oxidizing bacteria dominate the microbial community at the surface water of a CO2-rich hydrothermal spring located in Tenorio Volcano National Park, Costa Rica

“…Worldwide, several ecosystems have been reported in which CO2 is naturally released at high levels. At these extreme sites termed mofettes CO2 migrates from the lithosphere to the surface water (wet mofettes) or the soil (dry mofettes) (Kämpf et al 2013;Krauze et al 2017). In addition to the high levels of CO2 these environments are characterized by the presence of other gases such as H2S, H2, and CH4, similar to what was found in the Borbollones (Oppermann et al 2010;Beulig et al 2015;Frerichs et al 2013).…”

Insights into microbial community structure and function from a shallow, simulated CO2‐leakage aquifer demonstrate microbial selection and adaptation

“…PD_MW2 has the potential to use formate and hydrogen for methanogenesis (Thauer et al ., ). These observations agree with previous findings, as these pathways have been utilized by methanogens in carbon storage environments (Stevens et al ., ), and the presence of CO 2 has been previously suggested to promote methanogenesis in subsurface environments (Ham et al ., ; Krauze et al ., ).…”

“…All genes necessary for hydrogenotrophic methanogenesis were identified in the recovered Methanoregula draft genome (Fig. ), supporting this potential mechanism, which has also been proposed for other CO 2 storage environments (Morozova et al ., ; Krauze et al ., ).…”

“…While these studies begin to investigate how microbial communities will contribute to carbon, nitrogen and sulfur cycling in the CO 2 saturated ecosystem, the microbial communities of these natural analog sites have had thousands of years to adapt to these conditions. Mofettes (surface releases of volcanic gases, primarily CO 2 ) represent additional high CO 2 , acidic ecosystems, which due to their short-term nature have also been suggested as natural analog sites for potential CO 2 leakage and have been evaluated from a microbial ecology standpoint (Beulig et al, 2015;Krauze et al, 2017). Mofette microbial communities were found to be dominated by chemolithotrophic sulfur oxidizers, such as Sulfuricurvum and Sulfurimonas, various acetogenic genera within the Acidobacteria and methanogenic taxons such as Methanomicrobiales and Methanosarcinales (Beulig et al, 2015;Krauze et al, 2017).…”

“…Mofettes (surface releases of volcanic gases, primarily CO 2 ) represent additional high CO 2 , acidic ecosystems, which due to their short-term nature have also been suggested as natural analog sites for potential CO 2 leakage and have been evaluated from a microbial ecology standpoint (Beulig et al, 2015;Krauze et al, 2017). Mofette microbial communities were found to be dominated by chemolithotrophic sulfur oxidizers, such as Sulfuricurvum and Sulfurimonas, various acetogenic genera within the Acidobacteria and methanogenic taxons such as Methanomicrobiales and Methanosarcinales (Beulig et al, 2015;Krauze et al, 2017). However, to date, no studies have yet determined the metabolic potential of freshwater CO 2 leakage scenarios expected from GCS operations by looking at the microbial ecology in a real subsurface aquifer after controlled CO 2 injection.…”