Geological and hydrogeochemical research, tools for karst management in the north of the Caraş Gorges (Banat Mountains, Romania)

The karst geosystems functioning frequently implies very quick mass and energy transfers, which make them highly sensitive to any natural or anthropogenic disturbance. Therefore, the groundwater resources, threatened by agricultural and industrial pollution, should be carefully exploited, taking into account the intrinsic vulnerability of the region. This paper aims to present the results of the geological, geomorphological and hydrogeochemical studies carried out in the Banat Mountains (Romania), in order to widely assess and map the vulnerability of the most exposed karst aquifers. Following the principles of the EPIK method and using GIS, we were able to delineate upon degree 4 vulnerability classes (low, moderate, high, very high). Moreover, each unit has been assigned to a specific protection framework, comprising suitable management solutions, designed for environmental managers

Geological and ecological assessment of the exposure degree of the Zăton-Bulba karst system (Mehedinţi Plateau) to anthropogenic hazards: intrinsic vulnerability and biodiversity study

The Mehedinţi Plateau represents an area highly marked by the intensity of the karst processes and by the diversity of the exokarst and endokarst features. The analyzed area includes two parallel limestone bars, developed on the Carpathian structures direction (NNE-SSW). The geological and geomorphological research, guided by a working protocol similar to that of the EPIK method, highlighted the role played by the lithology, structure, tectonics, epikarst and protective cover, related to the infiltration conditions, flow parameters and impact area of a potential contamination event; also, we carried on microtectonic studies on the Bulba Valley, Peşterii Hill, Podul Natural Cave and Bulba Cave. In addition to the results obtained following the EPIK method protocol, we bring forward data concerning the water quality, performing hydrogeochemical analyses on water samples collected from the main sources in the region. Our research has been focused on TDS, on cations (Ca2+, Mg2+, Na+, K+, NH4+) and on anions (HCO3-, Cl-). We conclude by modelling the cumulative abundance and the species richness of the harvestmen (Opiliones) in the studied area, under different degrees of human impact on habitat

Total and Potentially Active Bacterial Communities Entrapped in a Late Glacial Through Holocene Ice Core From Scarisoara Ice Cave, Romania

Our understanding of the icy-habitat microbiome is likely limited by a lack of reliable data on microorganisms inhabiting underground ice that has accumulated inside caves. To characterize how environmental variation impacts cave ice microbial community structure, we determined the composition of total and potentially active bacterial communities along a 13,000-year-old ice core from Scarisoara cave (Romania) through 16S rRNA gene Illumina sequencing. An average of 2,546 prokaryotic gDNA operational taxonomic units (OTUs) and 585 cDNA OTUs were identified across the perennial cave ice block and analyzed in relation to the geochemical composition of ice layers. The total microbial community and the putative active fraction displayed dissimilar taxa profiles. The ice-contained microbiome was dominated by Actinobacteria with a variable representation of Proteobacteria, while the putative active microbial community was equally shared between Proteobacteria and Firmicutes. Accordingly, a major presence of Cryobacterium, Lysinomonas, Pedobacter, and Aeromicrobium phylotypes homologous to psychrotrophic and psychrophilic bacteria from various cold environments were noted in the total community, while the prevalent putative active bacteria belonged to Clostridium, Pseudomonas, Janthinobacterium, Stenotrophomonas, and Massilia genera. Variation in the microbial cell density of ice strata with the dissolved organic carbon (DOC) content and the strong correlation of DOC and silicon concentrations revealed a major impact of depositional processes on microbial abundance throughout the ice block. Post-depositional processes appeared to occur mostly during the 4,000–7,000 years BP interval. A major bacterial composition shift was observed in 4,500–5,000-year-old ice, leading to a high representation of Beta- and Deltaproteobacteria in the potentially active community in response to the increased concentrations of DOC and major chemical elements. Estimated metabolic rates suggested the presence of a viable microbial community within the cave ice block, characterized by a maintenance metabolism in most strata and growth capacity in those ice deposits with high microbial abundance and DOC content. This first survey of microbial distribution in perennial cave ice formed since the Last Glacial period revealed a complex potentially active community, highlighting major shifts in community composition associated with geochemical changes that took place during climatic events that occurred about 5,000 years ago, with putative formation of photosynthetic biofilms