Artículos científicos
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Ítem A long-term record of polythionates in the acid crater-lake of Poás volcano: Changes in the subaqueous input of fumarolic gases(IAVCEI. General Assembly. Pucón-Chile, 2004-01) Martínez, M.; Van Bergen, M. J.; Fernández, E.; Takano, B.; Malavassi, E.; Barboza, V.; Miura, Y.; Van der Laat, R.; Duarte, E.; Valdés, J.; Sáenz, W.Ítem ANTOLOGÍA SOBRE POLITIONATOS: COMPUESTOS DE AZUFRE EXISTENTES EN LOS LAGOS CRATÉRICOS DE VOLCANES ACTIVOS(Revista de Vulcanología, Sismología y Tectónica., 1999) Martínez-Cruz, MaríaEn la siguiente recopilación bibliográfica sobre los oxianiones de azufre llamados politionatos, con fórmula general SxO6 2-, se contemplan algunas de sus propiedades físico-químicas, y se hace énfasis principalmente en el hecho de que se ha encontrado que los cambios en la concentración total de los politionatos son un buen indicador de cambios en la actividad fumarólica subacuática de varios lagos cratéricos. La variación en la concentración de los ácidos politiónicos presentes en los lagos cratéricos, se ha observado y relacionado con actividad sísmica y la producción de erupciones freáticas en los volcanes Poás en Costa Rica; Kusatsu Shirane en Japón, y el Ruapehu en Nueva Zelanda. Los oxianiones conteniendo al azufre en varios estados de oxidación han sido encontrados en ambientes tales como fumarolas volcánicas, fuentes termales, en el agua sumamente ácida de algunos lagos cratéricos, sedimentos de lagos, aguas residuales de industrias mineras y solfataras. El monitoreo de la variación en la concentración de ciertas especies químicas en los sistemas volcánicos constituye una herramienta de gran importancia en la predicción de actividad volcánica.Ítem Co-ideation of disaster preparedness strategies through a participatory design approach: Challenges and opportunities experienced at Turrialba volcano, Costa Rica(Elsevier, 2015) Van Manen, Saskia; Avard, Geoffroy; Martínez-Cruz, MaríaDisaster preparedness is key to coping and adaptation during the immediate aftermath of a natural hazard, but the majority of those at risk do not feel prepared. In this participatory action research we investigate the use of a participatory design approach to increase disaster preparedness around Turrialba volcano, Costa Rica. We present a case study of two ideation workshops and explore the process, outcomes, challenges and opportunities during ideation. Socio-cognitive dimensions, specifically risk and responsibility transfer, appear to be important factors influencing the uptake of self-protective measures. Challenges in workshop facilitation were of a human, cultural and resource nature. However, the overall process was successful with participants showing indications of empowerment and a number of pressing design opportunities identified.Ítem Comparación de la composición química de partículas PM10 y PM2,5 colectadas en ambientes urbanos y zonas volcánicas del área metropolitana de Costa Rica(Revista Ciencias Ambientales, 2014-12) Herrera, Jorge; Rojas, José Félix; Martínez, María; Avard, Geoffroy; De Moore, Martin; Sáenz, Wendy; Beita, Víctor H.; Rodríguez, Agustín; Agüero, AlejandroSe muestrearon, en forma simultánea, partículas PM10 y PM2,5 en ambientes urbanos y volcánicos del área metropolitana de Costa Rica, durante octubre y noviembre de 2012. En las áreas industriales y comerciales de alto flujo vehicular (La Uruca, Heredia y Belén) se presentaron concentraciones másicas significativamente superiores (42-29 μgm-3) de PM10 y PM2,5 en comparación con las registradas en la zona volcánica. Las concentraciones diarias de PM10 y PM2,5, obtenidas en el volcán Poás variaron entre 3-14 μgm-3 y 2-11 μgm- 3, respectivamente. Sin embargo, la acidez de las partículas colectadas en el Poás es mayor a la acidez correspondiente a ambientes urbanos, debido, probablemente, a una ocurrencia menor de tasas de neutralización. El aporte de iones secundarios resultó ser la principal contribución (40%) a la composición de las PM10 volcánicas, a diferencia de las colectadas en centros urbanos.Ítem Extremely high diversity of sulfate minerals in caves of the Irazú Volcano (Costa Rica) related to crater lake and fumarolic activity(International Journal of Speleology, 2018-05) Ulloa, Andrés; Gázquez, Fernando; Sanz-Arranz, Aurelio; Medina, Jesús; Rull, Fernando; Calaforra, José María; Alvarado, Guillermo E.; Martínez, María; Avard, Geoffroy; De Moor, J. Maarten; De Waele, JoThe caves of the Irazú volcano (Costa Rica), became accessible after the partial collapse of the NW sector of the Irazú volcano in 1994, offering the opportunity to investigate active minerogenetic processes in volcanic cave environments. We performed a detailed mineralogical and geochemical study of speleothems in the caves Cueva los Minerales and Cueva Los Mucolitos, both located in the northwest foothills of the main crater. Mineralogical analyses included X-ray diffraction (XRD) and Raman spectroscopy, while geochemical characterization used Energy Dispersive X-ray spectroscopy (EDX) coupled to Scanning Electron Microscopy (SEM). In addition, measurements of environmental parameters in the caves, cave drip water and compilation of geochemical analyses of the Irazú volcanic lake (~150 m above the cave level) and fumarole analyses were conducted between 1991 and 2014. We identified forty-eight different mineral phases, mostly rare hydrated sulfates of the alunite, halotrichite, copiapite, kieserite and rozenite groups, thirteen of which are described here as cave minerals for the first time. This includes the first occurrence in cave environments of aplowite, bieberite, boyleite, dietrichite, ferricopiapite, ferrinatrite, lausenite, lishizhenite, magnesiocopiapite, marinellite, pentahydrite, szomolnokite, and wupatkiite. The presence of other new cave minerals such as tolbachite, mercallite, rhomboclase, cyanochroite, and retgersite, is likely but could not be confirmed by various mineralogical techniques. Uplifting of sulfurous gases, water seepage from the Irazú volcanic lake and hydrothermal interactions with the volcanic host rock are responsible for such extreme mineralogical diversity. These findings make the caves of the Irazú volcano a world-type- reference locality for investigations on the formation and assemblage of sulfate minerals and the biogeochemical cycle of sulfur, with potential implications for Astrobiology and Planetary science.Ítem Gas measurements from the Costa Rica–Nicaragua volcanic segment suggest possible along-arc variations in volcanic gas chemistry(Elsevier, 2014) Aiuppa, A.; Robidoux, P.; Tamburello, G.; Conde, V.; Galle, B.; Avard, G.; Bagnato, E.; De Moor, J. M.; Martínez, M.; Muñoz, A.Obtaining accurate estimates of the CO2output from arc volcanism requires a precise understanding of the potential along-arc variations in volcanic gas chemistry, and ultimately of the magmatic gas signature of each individual arc segment. In an attempt to more fully constrain the magmatic gas signature of the Central America Volcanic Arc (CAVA), we present here the results of a volcanic gas survey performed during March and April 2013 at five degassing volcanoes within the Costa Rica–Nicaragua volcanic segment (CNVS). Observations of the volcanic gas plume made with a multicomponent gas analyzer system (Multi-GAS) have allowed characterization of the CO2/SO2-ratio signature of the plumes at Poás (0.30 ±0.06, mean ±SD), Rincón de la Vieja (27.0 ±15.3), and Turrialba (2.2 ±0.8) in Costa Rica, and at Telica (3.0 ±0.9) and San Cristóbal (4.2 ±1.3) in Nicaragua (all ratios on molar basis). By scaling these plume compositions to simultaneously measured SO2fluxes, we estimate that the CO2outputs at CNVS volcanoes range from low (25.5 ±11.0tons/day at Poás) to moderate (918 to 1270 tons/day at Turrialba). These results add a newinformation to the still fragmentary volcanic CO2output data set, and allow estimating the total CO2output from the CNVS at 2835 ±1364tons/day. Our novel results, with previously available information about gas emissions in Central America, are suggestive of distinct volcanic gas CO2/ST(=SO2+H2S)-ratio signature for magmatic volatiles in Nicaragua (∼3) relative to Costa Rica (∼0.5–1.0). We also provide additional evidence for the earlier theory relating the CO2-richer signature of Nicaragua volcanism to increased contributions from slab-derived fluids, relative to more-MORB-like volcanism in Costa Rica. The sizeable along-arc variations in magmatic gas chemistry that the present study has suggested indicate that additional gas observations are urgently needed to more-precisely confine the volcanic CO2from the CAVA, and from global arc volcanism.Ítem Geophysical, geochemical and geodetical signals of reawakening at Turrialba volcano (Costa Rica) after almost 150 years of quiescence(Elsevier, 2010-11) Martini, F.; Tassi, F.; Vaselli, O.; Del Potro, R.; Martínez, M.; Van der Laat, R.; Fernández, E.Turrialba is a basaltic–andesitic stratovolcano (3340 masl), in the Cordillera Volcánica Central in Costa Rica. After the last eruption (1864–1866), volcanic manifestations were limited to weak fumarolic discharge (continuous since 1980) from the summit. From 1996 onward, the degassing activity has progressively been increasing, reaching its climax after 2005. New fumaroles have appeared in the Central and West summit craters, the latter now being the most active, and in the fracture system in between, showing sulphur deposits and progressively increasing degassing rate. In 2004, fumaroles and new fissures have appeared on the SW outer and SSW distal flanks, the latter being located along a major NE-oriented tectonic lineament. Fumarolic temperatures at the bottom of the West crater have increased from 88 to 282 °C in early 2008. Changes in chemical and isotopic compositions of discharged fluids have shown a progressive enhancing of the magmatic signature since 2001. Since late 2007, SO2 flux, measured with mini-DOAS, has increased two orders of magnitude (1 t/day in 2002 to 740 t/day in January 2008). The enhanced gas discharge at Turrialba volcano has caused significant interference on tropospheric O3 measurements at 2–3 km altitude ~50 kmWfrom the volcano. Seismic swarms followed an increasing trend consistent with that of the fumaroles. The maximum seismic activity to date, up to thousands of events/day, was recorded in mid 2007. An inflationary trend was observed in the crater area. In this paper we present for the first time all the available data on the activity of Turrialba volcano. New geophysical, geodetical and geochemical data and published geophysical and geochemical data are presented and discussed as a whole. The multidisciplinary approach indicated that from 1996 to 2009 three stages, deriving by the delicate equilibrium between the hydrothermal and the magmatic reservoirs, were recognized. The magmatic-dominated phase is still prevailing as evidenced by the fact that, while completing the present paper, on the 4th of January 2010 at 16.57 (GMT) a loud explosion occurred at the West crater and was followed by three others spaced out every 10 min. These events were interpreted as associated with phreatic eruptions.Ítem Halogen activation in the plume of Masaya volcano: field observations and box model investigations(Atmospheric Chemistry and Physics, 2020) Rüdiger, Julian; Gutmann, Alexandra; Bobrowski, Nicole; Liotta, Marcello; De Moor, J. Maarten; Sander, Rolf; Dinger, Florian; Tirpitz, Jan-Lukas; Ibarra, Martha; Saballos, Armando; Martínez, María; Mendoza, Elvis; Ferrufino, Arnoldo; Stix, John; Valdés, Juan; Castro, Jonathan M.; Hoffmann, ThorstenVolcanic emissions are a source of halogens to the atmosphere. Rapid reactions convert the initially emitted hydrogen halides (HCl, HBr, HI) into reactive species e.g. BrO, Br2, BrCl, ClO, OClO and IO. The activation reaction mechanisms in the plume consume ozone (O3), which is entrained by in-mixed ambient air. In this study, we present observations of the oxidation of bromine, chlorine and iodine during the first 11 minutes after emission, investigating the 25 plume of Santiago Crater of Masaya volcano in Nicaragua. Two field campaigns were conducted, in July 2016 and September 2016. The sum of the reactive species of the respective halogens were determined by gas diffusion denuder sampling followed by GC-MS analysis, while the total amounts of halogens and sulfur amounts were obtained by alkaline trap sampling with subsequent IC and ICP-MS measurements. Both ground and airborne sampling with an unmanned aerial vehicle (including a denuder sampler in combination with an electrochemical SO2 sensor) was performed at different distances from the crater rim. 30 The in-situ measurements were accompanied by remote sensing observations (DOAS). For bromine, the reactive fraction increased from 0.20 ± 0.13 at the crater rim to 0.76 ± 0.26 at 2.8 km downwind, while chlorine showed an increase of the reactive fraction from (2.7±0.7)×10-4 to (11±3)×10-4 in the first 750 m. Additionally, a reactive iodine fraction of 0.3 at the crater rim and 0.9 at 2.8 km was measured. No significant increase in BrO/SO2 molar ratios was observed with the estimated age of the observed plume ranging from 1.4 min to 11.1 min. This study presents a comprehensive gas diffusion denuder data 35 set on reactive halogen species and compares BrO/SO2 ratios with the sum of all reactive Br species. With the observed field data, a chemistry box model (CAABA/MECCA) enabled the reproduction of the observed progression of the reactive bromine to total bromine ratio. An observed contribution of BrO to the reactive bromine fraction of about 10 % was reproduced in the first minutes of the model run. The model results emphasize the importance of ozone entrainment into the plume for the reproduction of the measured reactive bromine formation and the dependence on the availability of HXOY and NOX.Ítem Historia eruptiva del volcán Turrialba y sus impactos(Ambientico. Revista Mensual, 2015-06) Pacheco, Javier; Martínez, MaríaÍtem Mercury fluxes from volcanic and geothermal sources: an update(Geological Society, London, Special Publications, 2014-08-02) Bagnato, E.; Tamburello, G.; Avard, G.; Martínez-Cruz, M.; Enrico, M.; Fu, X.; Sprovieri, M.; Sonke, J. E.We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere and present new data from seven active volcanoes (Poa´s, Rinco´n de la Vieja, Turrialba, Aso, Mutnovsky, Gorely and Etna) and two geothermal fields (Las Pailas and Las Hornillas). The variability of Hg contents (c. 4–125 ng m23) measured in gaseous emissions reflects the dynamic nature of volcanic plumes, where the abundances of volatiles are determined by the physical nature of degassing and variable air dilution. Based on our dataset and previous work, we propose that an average Hg/SO2 plume mass ratio of c. 7.8 × 10-6 (+1.5 × 10-6; 1 SE, n= 13) is best representative of open-conduit quiescent degassing. Taking into account the uncertainty in global SO2 emissions, we infer a global volcanic Hg flux from persistent degassing of c. 76+30 t a-1. Our data are derived from active volcanoes during non-eruptive periods and we do not have any direct constraint on the Hg flux during periods of elevated SO2 flux associated with large-scale effusive or explosive eruptions. This suggests that the time-averaged Hg flux from these volcanoes is even larger if the eruptive contribution is considered. Conversely, closed-conduit degassing and geothermal emissions contribute modest amounts of Hg.Ítem Microbial Community Structure Along a Horizontal Oxygen Gradient in a Costa Rican Volcanic Influenced Acid Rock Drainage System(Springer, 2020) Arce-Rodríguez, Alejandro; Puente-Sánchez, Fernando; Avendaño, Roberto; Libby, Eduardo; Mora-Amador, Raúl; Rojas-Jiménez, Keilor; Martínez, María; Pieper, Dietmar H.; Chavarría, MaxWe describe the geochemistry and microbial diversity of a pristine environment that resembles an acid rock drainage (ARD) but it is actually the result of hydrothermal and volcanic influences. We designate this environment, and other comparable sites, as volcanic influenced acid rock drainage (VARD) systems. The metal content and sulfuric acid in this ecosystem stem from the volcanic milieu and not from the product of pyrite oxidation. Based on the analysis of 16S rRNA gene amplicons, we report the microbial community structure in the pristine San Cayetano Costa Rican VARD environment (pH = 2.94–3.06, sulfate ~ 0.87– 1.19 g L−1, iron ~35–61 mg L−1 (waters), and ~ 8–293 g kg−1 (sediments)). San Cayetano was found to be dominated by microorganisms involved in the geochemical cycling of iron, sulfur, and nitrogen; however, the identity and abundance of the species changed with the oxygen content (0.40–6.06 mg L−1) along the river course. The hypoxic source of San Cayetano is dominated by a putative anaerobic sulfate-reducing Deltaproteobacterium. Sulfur-oxidizing bacteria such as Acidithiobacillus or Sulfobacillus are found in smaller proportions with respect to typical ARD. In the oxic downstream, we identified aerobic ironoxidizers (Leptospirillum, Acidithrix, Ferrovum) and heterotrophic bacteria (Burkholderiaceae bacterium, Trichococcus, Acidocella). Thermoplasmatales archaea closely related to environmental phylotypes found in other ARD niches were also observed throughout the entire ecosystem. Overall, our study shows the differences and similarities in the diversity and distribution of the microbial communities between an ARD and a VARD system at the source and along the oxygen gradient that establishes on the course of the river.Ítem Morphological and geochemical features of crater lakes in Costa Rica: an overview(Journal of limnology, 2009) Tassi, Franco; Vaselli, Orlando; Fernández, Erik; Duarte, Eliecer; Martínez, María; Delgado Huertas, Antonio; Bergamaschi, FrancescoThis paper describes the compositional and morphological features of the crater lakes found in the volcanoes of Rincón de La Vieja, Poás, Irazú, Congo and Tenorio volcanoes (Costa Rica). As evidenced by the distribution of the water and dissolved gas chemistry along vertical profiles, the different fluid sources feeding the lakes reflect the present status of each of the volcanic systems. The chemical features of the Caliente (Poás volcano) and Rincón crater (Rincón de la Vieja volcano) lakes are mainly dependent on i) inputs of magmatic fluids from sub-lacustrine fumaroles and ii) water-rock interaction processes. Conversely, the Irazú lake is mainly affected by the presence of CO2(H2S)-rich fluids discharged from a hydrothermal system, which masked possible magmatic fluid contributions. Rainfall and organic activity are the main factors responsible for the chemical composition of Hule, Botos, Congo and Tenorio lakes. The chemical and isotopic water composition of Botos, Irazú and Hule lakes have displayed no significant variations along the vertical profiles. In contrast, Caliente lake shows a distinctive chemical stratification, mainly involving F-, Cl- and SO4 2-. The behaviour of these compounds seems to be governed by both dissolution of highly acidic species, i.e. HF, HCl and SO2 released from the magmatic environment, and microbial activity. Despite the significant increases with depth of dissolved CO2 at Caliente and Irazú lakes, the hazard for Nyos-type gas eruptions can be considered negligible, since i) the water volumes are too small and ii) the convective heat transfer limits the CO2 recharge rate. The relatively high concentrations of dissolved CO2 measured at the maximum depth of the Hule lake are likely produced by both degradation of organic material and degassing from a deep source. The sporadic episodes of fish deaths recently observed in this lake can be associated with lake overturn processes that have favoured the rise up to the lake surface of deep, oxygen-depleted waters.Ítem New insights into Kawah Ijen’s volcanic system from the wet volcano workshop experiment(Geological Society London Special Publications, 2016-02-25) Gunawan, Hendra; Caudron, Corentin; Pallister, John; Primulyana, Sofyan; Christenson, Bruce; Mccausland, Wendy; Van Hinsberg, Vincent; Lewicki, Jennifer; Rouwet, Dmitri; Kelly, Peter; Kern, Christoph; Werner, Cynthia; Johnson, Jeffrey B.; Saing, Ugan; Suparjan; Budi Utami, Sri; Kamil Syahbana, Devy; Heri Purwanto, Bambang; Sealing, Christine; Martínez Cruz, María; Maryanto, Sukir; Bani, Philipson; Laurin, Antoine; Schmid, Agathe; Bradley, Kyle; Agung Nandaka, I Gusti Made; Hendrasto, MochammadVolcanoes with crater lakes and/or extensive hydrothermal systems pose significant challenges with respect to monitoring and forecasting eruptions, but they also provide new opportunities to enhance our understanding of magmatic–hydrothermal processes. Their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest and eruption, yet they also enable sampling and monitoring of geochemical tracers. Here, we describe the outcomes of a highly focused international experimental campaign and workshop carried out at Kawah Ijen volcano, Indonesia, in September 2014, designed to answer fundamental questions about how to improve monitoring and eruption forecasting at wet volcanoes.Ítem Relationship between Diffuse CO2 Degassing and Volcanic Activity. Case Study of the Poás, Irazú, and Turrialba Volcanoes, Costa Rica(Frontiers in Earth Science, 2017-10-11) Epiard, Matthieu; Avard, Geoffroy; De Moor, J. Maarten; Martínez Cruz, María; Barrantes Castillo, Gustav; Bakkar, HenrietteActive volcanoes exhibit diffuse gas emanations through the ground, the most abundant species of which is CO2. However, the relationship between diffuse degassing and volcanic activity is not often clear and some volcanoes may have low diffuse degassing levels despite having strong volcanic activity. The main goals of this study are to quantify diffuse CO2 degassing and determine whether patterns exist in relation to volcanic activity through the study of Turrialba, Poás, and Irazú, three active volcanoes in Costa Rica which are at different stages of activity. Structural controls of spatial distribution of diffuse degassing were also investigated. Measurement campaigns were conducted using the accumulation chamber method coupled with 10 cm depth ground temperature sampling with the aim of estimating the total diffuse CO2 degassing budget. The total amount of CO2 emitted diffusely by each volcano is ∼113 ± 46 t/d over ∼0.705 km2 for Turrialba, 0.9 ± 0.5 t/d for Poás over ∼0.734 km2, 3.8 ± 0.9 t/d over ∼0.049 km2 for Irazú’s main crater, and 15±12 t/d over 0.0059 km2 for Irazú’s north flank. Turrialba and Poás volcano diffuse degassing budget represent about 10% of the whole gas output. Both volcanoes were in a transitional stage Active volcanoes exhibit diffuse gas emanations through the ground, the most abundant species of which is CO2. However, the relationship between diffuse degassing and volcanic activity is not often clear and some volcanoes may have low diffuse degassing levels despite having strong volcanic activity. The main goals of this study are to quantify diffuse CO2 degassing and determine whether patterns exist in relation to volcanic activity through the study of Turrialba, Poás, and Irazú, three active volcanoes in Costa Rica which are at different stages of activity. Structural controls of spatial distribution of diffuse degassing were also investigated. Measurement campaigns were conducted using the accumulation chamber method coupled with 10 cm depth ground temperature sampling with the aim of estimating the total diffuse CO2 degassing budget. The total amount of CO2 emitted diffusely by each volcano is ∼113 ± 46 t/d over ∼0.705 km2 for Turrialba, 5.8 ± 0.5 t/d for Poás over ∼0.734 km2, 3.8 ± 0.9 t/d over ∼0.049 km2 for Irazú’s main crater, and 15 ± 12 t/d over 0.0059 km2 for Irazú’s north flank. Turrialba and Poás volcanoes diffuse degassing budgets represent about 10% of whole gas output. Both volcanoes were in a transitional stage and the opening of new conduits may cause a loss in diffuse degassing and an increase of active degassing. Numerous diffuse degassing structures were also identified. At Turrialba, one of which was closely associated with the collapse of a crater wall in 2014 during the initiation of a new period of heightened eruptive activity. Similar structures were also observed on the outer slopes of the west crater, suggesting strong alteration and perhaps destabilization of the upper outer cone. Irazú’s north flank is highly permeable and has experienced intense hydrothermal alteration.Ítem 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(Extremophiles, 2019-01-01) Arce-Rodríguez, Alejandro; Puente-Sánchez, Fernando; Avendaño, Roberto; Martínez-Cruz, María; Maarten de Moor, J; Pieper, Dietmar H; Chavarría, MaxHere we report the chemical and microbial characterization of the surface water of a CO2-rich hydrothermal vent known in Costa Rica as Borbollones, located at Tenorio Volcano National Park. The Borbollones showed a temperature surrounding 60 °C, a pH of 2.4 and the gas released has a composition of ~ 97% CO2, ~ 0.07% H2S, ~ 2.3% N2 and ~ 0.12% CH4. Other chemical species such as sulfate and iron were found at high levels with respect to typical fresh water bodies. Analysis by 16S rRNA gene metabarcoding revealed that in Borbollones predominates an archaeon from the order Thermoplasmatales and one bacterium from the genus Sulfurimonas. Other sulfur- (genera Thiomonas, Acidithiobacillus, Sulfuriferula, and Sulfuricurvum) and iron-oxidizing bacteria (genera Sideroxydans, Gallionella, and Ferrovum) were identified. Our results show that CO2- influenced surface water of Borbollones contains microorganisms that are usually found in acid rock drainage environments or sulfur-rich hydrothermal vents. To our knowledge, this is the first microbiological characterization of a CO2- dominated hydrothermal spring from Central America and expands our understanding of those extreme ecosystems.