The geographic location of Andalusia, bordered by the Atlantic Ocean and the Mediterranean Sea, and its great topographic and climate diversity enable the analysis of different factors that condition ...the isotopic composition of precipitation and groundwater. A total of 42 karst springs representative of the main carbonate aquifers were selected in order to sample the base flow waters during the summer of 2020. Isotopic analyses revealed that groundwater δ18O was between −5.04 and −9.85‰ while that of δ2H was between −26.39 and −62.69‰. Weighted mean isotopic data for precipitation, from six IAEA stations in the study area, was between −4.67 and −9.06‰ for δ18O, and between −24.93 and −58.99 ‰ for δ2H. The results showed that diffuse flow groundwaters are lighter and have higher d‐excess than meteoric waters, which may be due to preferential recharge during winter months and the sub‐cloud evaporation effect. The spatial variation of d‐excess, with average values around 14 ‰ in the Atlantic watershed and 17 ‰ in the Mediterranean watershed, has showed for the first time the effect of the Atlantic‐Mediterranean divide on the isotopic composition of spring waters. Furthermore, a progressive decrease in δ18O towards the east of the study area seems to be related to the effects of continentality and altitude. This also allowed us to conclude that, in the areas with highest rainfall, springs drain waters with a relatively higher content of heavy isotopes than expected from the regional altitudinal gradient, while springs in drier areas discharge lighter waters. These differences can be attributed to a longer recharge period in the former, which extends in the warmer months or autumn and spring.
Isotopic analysis of groundwater from Andalusian karst springs for 2H, 18O and deuterium excess showed differences between diffuse groundwater and meteoric waters isotopic composition. These differences are due to effects controlled by the great heterogeneity in the climate and relief in this territory. Specifically, it observes a notable influence of the Atlantic‐Mediterranean divide and of the recharge distribution of these systems in different periods of the year.
The role of faults in controlling groundwater flow in the Sahara and most of the hyper‐arid deserts is poorly understood due to scarcity of hydrological data. The Wadi Araba Basin (WAB), in the ...Eastern Sahara, is highly affected by folds and faults associated with Senonian tectonics and Paleogene rifting. Using the WAB as a test site, satellite imagery, aeromagnetic maps, field observations, isotopic and geochemical data were examined to unravel the structural control on groundwater flow dynamics in the Sahara. Analysis of satellite imagery indicated that springs occur along structurally controlled scarps. Isotopic data suggested that cold springs in the WAB showed a striking similarity with the Sinai Nubian aquifer system (NAS) water and the thermal springs along the Gulf of Suez (e.g., δ18O = −8.01‰ to −5.24‰ and δD = −53.09‰ to −31.12‰) demonstrating similar recharge sources. The findings advocated that cold springs in the WAB represent a natural discharge from a previously undefined aquifer in the Eastern Desert of Egypt rather than infiltrated precipitation over the plateaus surrounding the WAB or through hydrologic windows from deep crystalline basement flow. A complex role of the geological structures was inferred including: (1) channelling of the groundwater flow along low‐angle faults, (2) compartmentalization of the groundwater flow upslope from high‐angle faults, and (3) reduction of the depth to the main aquifer in a breached anticline setting, which resulted in cold spring discharge temperatures (13–22°C). Our findings emphasize on the complex role of faults and folds in controlling groundwater flow, which should be taken into consideration in future examination of aquifer response to climate variability in the Sahara and similar deserts worldwide.
A conceptual model of groundwater flow in a highly folded and faulted setting within the Eastern Sahara, that is, Wadi Araba Basin (WAB).
Geomicrobiologies of the hot springs of Chumathang and Panamik (located in the Indus and Nubra valleys of eastern and northern Ladakh, respectively) were revealed and compared with the Lotus Pond ...spring of Puga Valley (eastern Ladakh), which is known for its mineralogical and ecological peculiarities. Physicochemically, the vent-waters of the explored springs, Chumathang_01, Panamik_01 and Panamik_02, were distinct from Lotus Pond, with wide variations in boron, chloride, lithium, magnesium and potassium concentrations. Their microbiomes encompassed several unique constituents, but resembled Lotus Pond in being highly diversified and bacterial-mesophiles-dominated. Higher diversities of thermophilic archaea were detected in Chumathang_01 compared to Panamik_01 or Panamik_02. Statistical analysis of the geochemical and microbiological data highlighted the overall uniqueness of Lotus Pond, the constraint imposed by high temperature on the diversity of most bacterial groups, and the potential role of
in-situ
geochemicals in helping mesophilic bacteria inhabit the high-temperature environments. While the microbiome architecture of the 86°C Chumathang_01 (having the highest bacterial species count) closely resembled that of the geochemically similar 78°C Panamik_01, both the biomes were apparently shaped by temperature and pH. In contrast, the distinctive geochemistry of the 81°C Lotus Pond was apparently instrumental in sustaining a microbiome similar to that of the cooler (70°C) Panamik_02.
The disadvantage of the known methods of hardening springs is the impossibility of their use when hardening springs of a conical shape or of a shape of a paraboloid of rotation, since they are ...intended only for cylindrical shape springs and are not suitable for conical shape springs or those of a shape of a paraboloid of rotation specifically because of the difference in the shape of the springs. One of the disadvantages of the known springs hardening mechanisms is the impossibility of hardening the inner surface of the conical compression springs. A new method of hardening springs is proposed, the unmatched advantage of which is the ability to create plastic deformations on the inner and outer surfaces of the spring coils compressed to contact and on the surfaces along the line of contact between the coils. A new advantageous mechanism for hardening springs is proposed, which makes it possible to harden the inner surface of compression springs having a conical shape or a paraboloid shape of rotation, in a compressed state.
We examine a series of carbonic warm and hot springs in northern New Mexico, USA: 1) Tierra Amarilla springs 2) Penasco Springs and 3) Soda Dam, Jemez and Indian hot springs. Spring geochemistry is ...compared to waters from the Valles Caldera geothermal system and to groundwater in nearby sedimentary aquifers. Multiple hydrochemical tracers are applied to quantitatively evaluate flow paths and mixing at varying distances from the caldera. We test three hypotheses for source and transport of waters to Tierra Amarilla and Penasco Springs: San Juan basin origin, meteoric flow from the Nacimiento Mountains, and/or influence from the Valles Caldera geothermal system. Geochemically, carbonic spring groups are distinct from meteoric and sedimentary aquifer waters. Based on isotopes of He and Sr, and concentrations of Cl, SO4, Li and B, we interpret these carbonic springs to be distal manifestations of fluid circulation along faults with a mixture of Valles Caldera geothermal waters, local meteoric and Paleozoic aquifer waters, with the potential for small contributions from the San Juan Basin aquifers. Semi-confined fault conduits, the Jemez fault and Nacimiento fault systems, provide connectivity and help explain geochemical similarities and mixing trends within carbonic spring systems, and between these systems and the distal Valles Caldera. In addition, Penasco Springs are interpreted to reflect a component of outflow from the geothermal system that crosses the Nacimiento Mountain basement block along NE-trending faults. Input of deeply sourced waters can degrade water quality by contributing significant salinity and trace metals to groundwater at distances of >50 km from geothermal systems, with faults acting as conduits for subsurface fluid flow.
•New Mexico's super Volcano has a more far reaching effect than previously believed.•Re-investigate hypotheses for source and transport of water to a series of springs.•Geochemistry highlights geothermal influence of Valles Caldera at springs.•Acceptance of previously disregarded hypothesis based on multiple natural tracers.
Hot spring biofilms are stable, highly complex microbial structures. They form at dynamic redox and light gradients and are composed of microorganisms adapted to the extreme temperatures and ...fluctuating geochemical conditions of geothermal environments. In Croatia, a large number of poorly investigated geothermal springs host biofilm communities. Here, we investigated the microbial community composition of biofilms collected over several seasons at 12 geothermal springs and wells. We found biofilm microbial communities to be temporally stable and highly dominated by
Cyanobacteria
in all but one high-temperature sampling site (Bizovac well). Of the physiochemical parameters recorded, temperature had the strongest influence on biofilm microbial community composition. Besides
Cyanobacteria
, the biofilms were mainly inhabited by
Chloroflexota
,
Gammaproteobacteria
, and
Bacteroidota
. In a series of incubations with
Cyanobacteria
-dominated biofilms from Tuhelj spring and
Chloroflexota
- and
Pseudomonadota
-dominated biofilms from Bizovac well, we stimulated either chemoorganotrophic or chemolithotrophic community members, to determine the fraction of microorganisms dependent on organic carbon (in situ predominantly produced via photosynthesis) versus energy derived from geochemical redox gradients (here simulated by addition of thiosulfate). We found surprisingly similar levels of activity in response to all substrates in these two distinct biofilm communities, and observed microbial community composition and hot spring geochemistry to be poor predictors of microbial activity in the study systems.
Karst aquifers present hydrogeological characteristics that distinguish them from others such as fractured and granular aquifers. In particular, they are characterized by highly heterogeneous ...functioning (large temporal and spatial variability), which makes difficult the application of traditional research methods to karst hydrogeology. For this reason, during the last decades, hydrogeochemical tools have been developed for carbonate aquifers characterization by means of spatial and temporal hydrochemical variability, mixing processes (recharge vs. stored water in the system), groundwater origin (saturated/unsaturated zones, epikarst, etc.), karstification degree and, in general, the hydrogeological functioning of karst aquifers. In the present work, some of the most used techniques to study this type of media are applied to pilot sites from South Spain, in order to show hydrogeochemical processes related to karst aquifers functioning: groundwater origin, distribution of its chemical composition, aquifer behavior, water residence time, substratum influence and geochemical modelling. The results display that the combination of different hydrogeochemical tools provides a comprehensive understanding of the functioning of karst systems, which is useful for groundwater management and protection as well as for environmental applications (groundwater ecodependent systems, wetlands, coastal aquifers, etc).
One third of Turkey’s surface is underlain by carbonate rocks that have been subdivided into four karst regions. The carbonate rock units are about 200 km wide along the Taurus Mountains that attain ...elevations of 2500 m. Karst features of western Turkey bordering the Aegean and Mediterranean seas demonstrate the tectonic, lithological and climatic controls on the occurrence, movement, and chemical characteristics of groundwater. In Turkey all karstic feature, such as lapies, caves, sinkholes, uvalas, poljes, ground river valleys developed in all karstic areas. Karstification is related not only to the thickness and to purity of limestone, climate and height but also to tectonic movements. Water resources of karst terrains of Turkey are relatively rich and as such are very important for the economic development of the country. High mountain chains, very often associated with the karst terrains, are responsible for some important and beneficial characteristics of these water resources. Four karst regions are: (1) Taurus karst region, (2) southeast Anatolia karst region, (3) central Anatolia karst region, and (4) northwest Anatolia and Thrace karst regions.
Semnan thermal springs with high TDS and moderate temperature are located northwest of Semnan, the northern part of Iran. The spatial and temporal variations of physicochemical characteristics of the ...thermal and cold springs were investigated for the recognition of origin and dominant hydrogeochemical processes. Results show that the thermal springs have the same origin, but due to different ascending flow paths and different conductive cooling mechanism, their temperatures vary. The chemical composition of thermal waters is controlled by dolomite, halite and sulfate minerals dissolution and calcite precipitation and bacterial sulfate reduction. The concentration of major and trace elements in the thermal springs does not change in wet and dry seasons notably because they are derived from old groundwater with deep circulation and high temperature. Seasonal change in the concentration of some trace elements is due to the seasonal variation of pH, Eh, temperature and dilution by shallow waters. Decreasing SO
4
and carbonate saturation index and increasing Na/Cl ratios and Ca content in the dry season show dilution effect caused by the previous heavy rainfall events. The temperature of the heating reservoir based on K–Mg, chalcedony, quartz and chemical equilibrium approach was approximately estimated in the range of 60–80 °C. Hydrogeologically, a conceptual model was suggested for the thermal springs. The general groundwater flow direction is probably from the dolomite Lar Formation in Chenaran anticline toward the adjacent syncline in a confined condition, and then a thrust fault acts as a conduit and redirects the thermal water to the emerging springs at the surface.
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