Hydrogeology and geochemistry of the sulfur karst springs at Santa Cesarea Terme (Apulia, southern Italy)

This work describes the geochemical and hydrogeological characteristics of Santa Cesarea Terme, an active sulfuric acid speleogenetic system located along the Adriatic coastline (Apulia, southern Italy). It represents a very peculiar site, where rising thermal and acidic waters mix with seawater creating undersaturated solutions with respect to CaCO3, able to dissolve and corrode limestone and create caves. The Santa Cesarea Terme system is composed of four caves: Fetida, Sulfurea, Gattulla, and Solfatara. Hypogene morphologies and abundant deposits of native sulfur (especially in Gattulla Cave) and sulfate minerals are present in these caves. Fetida and Gattulla caves were investigated primarily because they are easily accessible throughout the whole year through artificial entrances, the other caves being reachable only from the sea. Geochemical analysis of water, monitoring of cave atmosphere, and measurement of the stable isotopes of S, O, and H helped to identify the main processes occurring in this complex cave system. In particular, changes in Ba2+ and Sr2+ concentration allowed for the identification of two main domains of influence, characterized by marine and rising acidic waters

Limestone and gypsum tablet weight loss in sulfuric acid speleogenetic caves of Southern Italy

The dissolution-corrosion (DC) is one of the most important key factors for the understanding of karst speleogenesis. Dissolution can be measured using tablets, balancing weight-loss/gain during the exposure in cave. In sulfuric acid environments, the oxidation of H2S is the most important process inducing speleogenesis (from here on, sulfuric acid speleogenesis is indicated as SAS). Here, the exposed surface of carbonate rocks is actively corroded by sulfuric acid (H2SO4). In aerate settings, CaCO3 can be easily replaced by CaSO4·2H2O, the most common SAS by-product, and produces an initial weight gain. The understanding of dissolution-corrosion (DC) rate in active SAS systems is a very important issue that can help in evaluating the speleogenetic stages of a cave, and in correlating them with landscape evolution, as demonstrated by previous studies carried out in the Grotta del Fiume at Frasassi, central Italy. Italy hosts 25 % of the known worldwide SAS caves, and some of them are still-active. In some of these, especially in those located in southern Italy, dissolution-corrosion rate studies started at the end of the 2015-beginning of 2016, and will continue until the beginning of 2021 (for a total of five whole years), to have a better distribution of weight loss/gain rates. The SAS systems under investigation are Ninfe Cave and Sibarite spa (in Calabria), Fetida Cave (Apulia), and Acqua Fitusa Cave (Sicily). Carbonate and gypsum tablets, 28 cm3, with a mean initial weight of 74 g, have been placed in the cave atmosphere, underwater, and at the interface zone. DC measurements showed interesting results, and demonstrated environmental parameters to be the essential controls in weight loss/gain rate. We observed that at the beginning of the experiment, DC was faster in underwater conditions, whereas during the last period of monitoring (after 582 days of permanence in cave) the dissolution at the interface zone increased, becoming even greater than the rate observed in subaqueous conditions

NEXT-GENERATION SEQUENCING FOR MICROBIAL CHARACTERIZATION OF BIOVERMICULATIONS FROM A SULFURIC ACID CAVE IN APULIA (ITALY)

Sulfuric acid cave systems host abundant microbial communities that can colonize several environments displaying a variety of morphologies i.e. white filamentous mats floating on the water surface, white creamy moonmilk deposits on the walls, and biovermiculations. Up to date, only few reports have described the microbiological aspects behind biovermiculation geomicrobiology of Italian sulfuric acid caves despite their overall abundance in the territory. Here, we present the first characterization of biovermicalution microbial populations from Santa Cesarea Terme (Apulia, Italy) using a next-generation sequencing approach. In this area, four sulfuric acid caves located along the coastline of the Adriatic sea have been explored. The mixing of sea and upwelling acidic water characterizes these environments, where very peculiar microbiological communities are visible both floating on the water but also growing on cave walls. In particular, we focused our analysis on biovermiculations from Fetida cave. This cave opens at the sea level, and moving from the entrance to the deeper part, it is possible to observe a decrease of marine influence and a corresponding increase of the acidic effect of the upwelling waters. Biovermiculations copiously cover ceiling and walls mainly in the deeper and middle environments of the cave, while they are absent close to the entrance. From a morphological point of view, biovermiculations have a widespread range of colors going from grey to dark brown with an overall slimy appearance; dendritic morphologies alternate to very dense wall-covering sheets. Vermiculation samples from different locations within the cave (mid-section and the end) have been collected. Total DNA was extracted from each sample and 16S rDNA sequences were analysed through Ilumina MiSeq platform. The main lineages found in all the samples included Gammaproteobacteria, Betaproteobacteria, Alphaproteobacteria, Bacteroidetes, Planctomycetes Actinobacteria and Acidobacteria. In particular, the samples from the deeper part of the cave had the highest abundance of Acidobacteria and showed the presence of Epsilonproteobacteria that can be related to bacterial sulfur-oxidizing activity typically occurring in sulfidic environments

Geochemical and hydrogeological characteristics of the Santa Cesarea terme sulfuric acid cave systems (Apulia, Southern Italy)

Santa Cesarea Terme (Apulia, southern Italy) stands as an important spa area, known since the nineteenth century. Several emergences of slightly thermal sulfidic waters flow out along a coastal sector of the Salento peninsula, and exhibit temperatures ranging between 22–25 °C. The carbonate sequence, consisting of over 5-km-thick Jurassic and Cretaceous limestone and dolostone, rests above Late Triassic evaporites and is unconformably overlain by Cenozoic calcareous successions. Starting from the Early Triassic, the area was part of the Apulian carbonate platform, characterized by shallow-water carbonate sedimentation. Since Cretaceous times, it experienced a number of transgression-regression phases, giving rise to a succession constituted by multiple unconformities. Eventually, during the Middle Pleistocene, the area underwent a severe regional uplift. The Santa Cesarea Terme area shows extensional and trans-tensional structures, with related pull-apart features. The NW–SE trans-tensional faults are the most diffuse, with subordinate presence of other fault systems, and appear to be the youngest set, controlling the development of the main karst landforms in the area. At the surface, these are mostly represented by sinkholes and dry valleys of different sizes and typologies, and by typical low-incised karst valleys. Apart from a number of inland caves (mostly of limited development), the most relevant karst features are distributed along the coast and correspond to three caves within the spa area and an additional cave further south. The four caves are carved at sea level and all have a direct access to the sea. Here, rising sulfidic waters meet and mix with seawater producing solutions with different geochemical contents. The sulfidic springs and the village of Santa Cesarea Terme are located on a structural high, with the caves elongated along the NW–SE fault zones. Inside the caves, that show quite large halls and galleries ending abruptly, it is possible to observe cupolas, rising channels, megacusps, submerged feeders, weathered walls, replacement pockets, and important deposits of gypsum, with abundant native sulphur coatings and jarosite. All these features allow to define the caves as Sulfuric Acid Speleogenesis (SAS) systems. During the last four years, geochemical data have been collected in order to characterize the composition of water flowing inside the caves, and a variety of parameters have been measured (including temperature, dissolved oxygen, conductivity, pH, etc.). They fall into the Na-Cl-SO4 sector of the Ludwig-Langelier diagram, with pH ranging from 7.2 to 7.8 (the latter value being mainly influenced by seawater-deep water mixing), and are colonized by whitish bacterial filaments (streamers). Brownish vermiculation deposits and white gypsum moonmilk diffusely cover walls and ceilings, especially where the amount of H2S-degassing is important. Experiments with limestone tablets are demonstrating the dissolution-corrosion to be an intense on-going process for presentday sulfuric acid speleogenesis

Corrigendum to ‘Vermiculations from karst caves: The case of Pertosa-Auletta system (Italy)’. (Catena (2019) 182 (104178) (S0341816219303200), (10.1016/j.catena.2019.104178))

DOI of original article:https://doi.org/10.1016/j.catena.2019.104178 .- Rosangela Addesso, Alessandro Bellino, Ilenia Maria D'Angeli, Jo De Waele, Ana Zélia Miller, Cristina Carbone, Daniela Baldantoni: Vermiculations from karst caves: The case of Pertosa-Auletta system (Italy) CATENA, Volume 182, November 2019, Pages 104178The authors regret the presence of incomplete information in the author affiliations (reported correctly above) and in the acknowledgments of the original article (provided in the amended version below). The authors are obliged to Mr. Vincenzo Manisera, speleologist of the MIdA Foundation, for sharing his experiences and for his invaluable help in all the field activities, to Dr. Sacha A. Berardo (University of Salerno, Italy) for the language editing, and to the two anonymous reviewers, who provided helpful comments and suggestions. Funding was provided by the Spanish project MINECO CGL2016-75590-P with ERDF funds, by the MIdA Foundation, which generously supported the whole project, and by the University of Salerno, which provided facilities for carrying out the research. The authors would like to apologise for any inconvenience caused.Peer reviewe

Microbial Communities in Vermiculation Deposits from an Alpine Cave

17 páginas.- 7 figuras.- 4 tablas.- referecias.- The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/feart.2020.586248/full#supplementary-material .- We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Morgana Cave is located in Val di Scerscen, Central Italian Alps. The cave opens at an altitude of 2,600 m a.s.l. close to the retreating glacier Vedretto di Scerscen, and its entrance was discovered 30 years ago hidden underneath the glacier. A characteristic of this cave is the occurrence of vermiculation deposits on the walls and ceiling. In general, the composition of the microbial communities in cave vermiculations is relatively unknown and rarely investigated. Here we present the data of a geomicrobiological study of vermiculations from an Alpine cave subjected to extreme climate conditions. The microbial communities were dominated by 13 main phyla of Bacteria, and contained a negligible percentage (<1%) of Archaea. The two major bacterial classes were Gammaproteobacteria and Betaproteobacteria, whose metabolic traits were mainly associated with the nitrogen cycle. In addition, psychrophilic and methanotrophic bacterial groups were identified. The occurrence of a large number of uncultured members, at the lowest taxonomic ranks, indicated the presence of still unexplored microbial taxa in the vermiculations.Funding was provided by the Spanish project MINECO CGL2016-75590-P with ERDF funds. The Rotary Club in Sondrio (Italy) also provided funds for sample analysis thanks to C. Mazza, M. Boccardi, and P. Nana, with the Municipality of Lanzada (S. Bardea) and the Istituto Mineralogico Valtellinese (I. Foianini) supporting the cave research project..- We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Late stage condensation-corrosion in high mountain marble caves (Val di Scerscen, Bernina Massif, Valtellina, Italy).

Póster presentado en el 20th EGU General Assembly, EGU2018, Proceedings from the conference held 4-13 April, 2018 in Vienna, Austria, p.1258Val di Scerscen is located in the Central Italian Alps (Northern Lombardy), in the scenic setting of Valmalenco. This area is not very rich in caves (only about one hundred, among the over 4800 caves known in Lombardy). Here, oceanic metamorphic rocks, which where uplifted during the Alpine orogenesis, dominate the terrains. A thin lens of whitish dolomitic marbles belonging to the Austroalpine Margna Nappe hosts a few short caves, right at the end of the tongue of the Scerscen glacier, on the southern slopes of Piz Bernina. This glacier and its meltwater probably strongly contributed to the cave evolution. The most important caves, opening at about 2600 m asl, are: Veronica cave (length: 638 m), Morgana cave (348 m), and Tana dei Marsooi (77 m). These are typical epiphreatic caves with juvenile pattern and with adjustment to the water table (Audra and Palmer, 2013), according to the glacier evolution and to the valley incision. With the important retreat of the glacier during the Holocene, the processes of cave evolution have changed. The runoff provided by the glacier became less and less important and the drainage changed with the migration of the tongue of the ice cover. Today, the groundwater flow is mainly active during spring due to snow melting on a restricted catchment. The underground climate is characteristic of alpine caves, with a low mean temperature. Condensation-corrosion processes (James, 2013) presently have a major control on the morphology of the cave passages. The shape of walls and ceilings has changed with the aerosol circulations according to the gradient of temperature between the cave and the exterior. Consequently, condensating waters carved smooth reliefs, notches and bell holes. Ongoing studies are focused on: (i) long term processes (U/Th dating on calcite crusts, cosmonucleide dating on quartz pebbles); (ii) current physical processes of condensation-corrosion, comprising microclimatic monitoring and in situ exposure of limestone tablets, and (iii) assessment of microbially mediated corrosion. In this sense, vermiculations were collected in different sites of Morgana cave and studied by DNA-based analyses and field emission scanning electron microscopy at the IRNAS-CSIC (Seville, Spain). Thanks to the collaboration with Leica Geosystems Italy it has been possible to test, for the first time in a cave, two new 3D mapping instruments: the “BLK360” laser scanner, the smallest and lightest of its kind weighing only 1 kg, and the “Pegasus Backpack”, a mobile mapping system which allows making a 3D scan of the environment by simply walking around. The data allowed creating 3D models of the Veronica cave which can be used both for morphological analysis and for virtual tours with educational purposes

Microbial Community Characterizing Vermiculations from Karst Caves and Its Role in Their Formation

13 páginas.- 4 figuras.- 3 tablas.- 60 referenciasThe microbiota associated with vermiculations from karst caves is largely unknown. Vermiculations are enigmatic deposits forming worm-like patterns on cave walls all over the world. They represent a precious focus for geomicrobiological studies aimed at exploring both the microbial life of these ecosystems and the vermiculation genesis. This study comprises the first approach on the microbial communities thriving in Pertosa-Auletta Cave (southern Italy) vermiculations by next-generation sequencing. The most abundant phylum in vermiculations was Proteobacteria, followed by Acidobacteria > Actinobacteria > Nitrospirae > Firmicutes > Planctomycetes > Chloroflexi > Gemmatimonadetes > Bacteroidetes > Latescibacteria. Numerous less-represented taxonomic groups (< 1%), as well as unclassified ones, were also detected. From an ecological point of view, all the groups co-participate in the biogeochemical cycles in these underground environments, mediating oxidation-reduction reactions, promoting host rock dissolution and secondary mineral precipitation, and enriching the matrix in organic matter. Confocal laser scanning microscopy and field emission scanning electron microscopy brought evidence of a strong interaction between the biotic community and the abiotic matrix, supporting the role of microbial communities in the formation process of vermiculations.Open access funding provided by Università degli Studi di Salerno within the CRUI-CARE Agreement. This work was supported by Musei Integrati dell’Ambiente Foundation, by the Spanish project MINECO [CGL2016-75590-P] with European Regional Development Fund and by University of Salerno [ORSA197159].Peer reviewe

Representative sampling sites in the cave.

<p>A) Calcite raft deposit at Chaos (SO1); B) moonmilk deposit at Piredda Hall (SO2 & SO3); C) manganese oxide deposit at Water Tower site (SO6) and D) sampling of a limestone wall at location Shaft (SO4)</p

Rarefaction analysis of the microbial communities at the different sampling points.

<p>Curves were calculated by MOTHUR with a 3% distance cutoff.</p