| Title | The biogeochemical vertical structure renders a meromictic volcanic lake a trap for geogenic CO2 (Lake Averno, Italy) |
| Abstract | Volcanic lakes are characterized by physicochemical favorable conditions for the development of reservoirs of C-bearing greenhouse gases that can be dispersed to air during occasional rollover events. By combining a microbiological and geochemical approach, we showed that the chemistry of the CO2- and CH4-rich gas reservoir hosted within the meromictic Lake Averno (Campi Flegrei, southern Italy) are related to the microbial niche differentiation along the vertical water column. The simultaneous occurrence of diverse functional groups of microbes operating under different conditions suggests that these habitats harbor complex microbial consortia that impact on the production and consumption of greenhouse gases. In the epilimnion, the activity of aerobic methanotrophic bacteria and photosynthetic biota, together with CO2 dissolution at relatively high pH, enhanced CO2- and CH4 consumption, which also occurred in the hypolimnion. Moreover, results from computations carried out to evaluate the dependence of the lake stability on the CO2/CH4 ratios, suggested that the water density vertical gradient was mainly controlled by salinity and temperature, whereas the effect of dissolved gases was minor, excepting if extremely high increases of CH4 are admitted. Therefore, biological processes, controlling the composition of CO2 and CH4, contributed to stabilize the lake stratification of the lake. Overall, Lake Averno, and supposedly the numerous worldwide distributed volcanic lakes having similar features (namely bio-activity lakes), acts as a sink for the CO2 supplied from the hydrothermal/magmatic system, displaying a significant influence on the local carbon budget. |
| Source | PloS one 13 (3), pp. 1–26 |
| Keywords | volcanic lakesAvernoCO2 and CH4 isotopesaerobic methanomorphic bacteriaphotosynthetic biota |
| Journal | PloS one |
| Editor | Public Library of Science, San Francisco, CA, Stati Uniti d'America |
| Year | 2018 |
| Type | Articolo in rivista |
| DOI | 10.1371/journal.pone.0193914 |
| Authors | Tassi F.[1,2], Fazi S.[3], Rossetti S.[3], Pratesi P.[1], Ceccotti M.[3], Cabassi J.[1,2], Capecchiacci F.[1], Venturi S.[1,2], Vaselli O.[1,2] |
| Text | 385621 2018 10.1371/journal.pone.0193914 Scopus 2 s2.0 85042926481 volcanic lakes Averno CO2 and CH4 isotopes aerobic methanomorphic bacteria photosynthetic biota The biogeochemical vertical structure renders a meromictic volcanic lake a trap for geogenic CO2 Lake Averno, Italy Tassi F. 1,2 , Fazi S. 3 , Rossetti S. 3 , Pratesi P. 1 , Ceccotti M. 3 , Cabassi J. 1,2 , Capecchiacci F. 1 , Venturi S. 1,2 , Vaselli O. 1,2 1 Department of Earth Sciences, University of Florence, Via G. La Pira 4, Florence, Italy, 2 IGG CNR Institute of Geosciences and Earth Resources, National Research Council of Italy, Via La Pira 4, Florence, Italy 3 IRSA, CNR Water Research Institute, National Research Council of Italy, Via Salaria, Monterotondo, Rome, Italy Volcanic lakes are characterized by physicochemical favorable conditions for the development of reservoirs of C bearing greenhouse gases that can be dispersed to air during occasional rollover events. By combining a microbiological and geochemical approach, we showed that the chemistry of the CO2 and CH4 rich gas reservoir hosted within the meromictic Lake Averno Campi Flegrei, southern Italy are related to the microbial niche differentiation along the vertical water column. The simultaneous occurrence of diverse functional groups of microbes operating under different conditions suggests that these habitats harbor complex microbial consortia that impact on the production and consumption of greenhouse gases. In the epilimnion, the activity of aerobic methanotrophic bacteria and photosynthetic biota, together with CO2 dissolution at relatively high pH, enhanced CO2 and CH4 consumption, which also occurred in the hypolimnion. Moreover, results from computations carried out to evaluate the dependence of the lake stability on the CO2/CH4 ratios, suggested that the water density vertical gradient was mainly controlled by salinity and temperature, whereas the effect of dissolved gases was minor, excepting if extremely high increases of CH4 are admitted. Therefore, biological processes, controlling the composition of CO2 and CH4, contributed to stabilize the lake stratification of the lake. Overall, Lake Averno, and supposedly the numerous worldwide distributed volcanic lakes having similar features namely bio activity lakes , acts as a sink for the CO2 supplied from the hydrothermal/magmatic system, displaying a significant influence on the local carbon budget. 13 Published version http //journals.plos.org/plosone/ The biogeochemical vertical structure renders a meromictic volcanic lake a trap for geogenic CO2 Lake Averno, Italy TASSI.pdf Articolo in rivista Public Library of Science 1932 6203 PloS one PloS one PLoS ONE PloS one Public Library of Science one PLoS 1 orlandovaselli VASELLI ORLANDO francotassi TASSI FRANCO VENTURI STEFANIA jacopo.cabassi CABASSI JACOPO simona.rossetti ROSSETTI SIMONA stefano.fazi FAZI STEFANO DTA.AD003.131.001 Geodinamica e processi geologici |
