The Niangziguan Spring is one of the largest karst springs in northern China and water in this spring area is the main water-supply source for people in Yangquan City for daily life, industrial ...processes and agricultural production. However, decreasing groundwater levels and growing waterpollution issues have been observed recently. Therefore, the objective of this study was to conduct a systematic analysis of water-flow reduction and water-quality deterioration of the Niangziguan Spring. The results show that various wastewater sources upstream of the spring, such as coal mining, and urban industrial and domestic effluents, have contributed to the deterioration of the Niangziguan Spring water quality. A mathematical model known as the one-order one-variable grey differential equation model GM(1,1) was employed to evaluate the contribution of climate change versus human activities potentially affecting the reduction of spring-water flow. The calculations for the period from 1979 to 2006 suggest that a contribution of human activities to water-flow reduction was 2.5 times greater than those that can be attributable to climate change. The research results obtained as presented in this paper can provide a scientific basis for rational exploitation of karst-water resources and environmental protection in this karst area of northern China.
The Songwe geothermal prospect is situated in western Tanzania in the Rukwa Rift of the western branch of the East African Rift System. Thermal springs discharge along NW–SE oriented fracture zones ...in two separate areas: in the main Songwe graben (Iyola, Main springs, Rambo and Kaguri) and eastern Songwe graben (Ikumbi). Lithologies forming and filling the Songwe graben are metamorphic gneiss and shist as basement rocks, overlain by the Karoo sandstones, and Red sandstones, both silt- and sandstones with a carbonatic matrix. In some areas of the graben, volcanic rocks intruded these formations forming basalt outflows. The discharge temperatures of springs are between 37 and 85 °C with Na-HCO
3
type fluids. Carbonate deposits surround most of the springs. Using previous geophysical, geological studies and historical fluid geochemical data and mineral data, the Songwe geothermal system interpretation was updated, including new reservoir fluid temperature, fluid flow pathway and water–rock interaction models. The classical geothermometers of K-Mg and Na-K-Ca
(Mg correction)
were used to predict the reservoir fluid temperature and show that fluid emerging in the Songwe area reaches temperatures between 125 and 148 °C. Reservoir fluid characteristics are reconstructed based on the geothermometer calculation and a PHREEQC model in which the deep fluid reacts with certain lithologies. Minerals precipitating at the surface and reservoir depth were used to calibrate the models. The models run at surface temperature were calibrated with minerals precipitating around the springs and suggest that Songwe thermal fluids interact with Red sandstone only, while Ikumbi spring water is the only spring that interacts with all lithologies (simplified referred to as: metamorphic rocks, Karoo and Red sandstone). The model run at reservoir temperature indicates that rising water is also in contact with Karoo sandstones and Ikumbi spring water composition is again influenced by the contact with all lithologies in the graben. Our conceptual model summarizes all data showing the meteoric origin of the fluids, the travel through the basement, rising along the Mbeya fault and the main reaction with sandstones through a lateral travel towards the hot springs. The proposed models reinforce the idea that carbonate dissolution from the sandstone layers is the most common water–rock interaction. Our model is supported by carbonate deposition observed in all springs, dominated by HCO
3
and Na.
Delineating spring protection zones is key to managing groundwater. This work presents a proposal for delineating spring protection zones (SPZs) that uses hydrogeological, topographical, land use, ...and climate characteristics as a basis to protect springs located in fractured volcanic media from potential contamination processes. This was accomplished through five stages: (1) identification of hydrogeological characteristics of the environments in which springs are located and physicochemical properties of water, (2) delineation of spring potential catchment zones, (3) estimation of spring recharge zones in the potential catchment zones, (4) SPZ proposal based on annual recharge analysis for each spring, and (5) projection of future land use and climate change scenarios. The result was a proposal of three typically established zones for protecting springs: SPZ1 was defined by a 50-m radius around springs, SPZ2 was delineated based on spring annual recharge zone estimate, and SPZ3 was considered the remainder of potential catchment zone. By delineating these zones, more suitable protection measures can be identified based on trends in land use and climate changes, measures which would thereby aid in sustainable use of these types of springs.
The Indian state of Odisha has a number of thermal springs. These thermal springs are located at eight places (Attri, Tarabalo, Deulajhari, Magarmuhan, Bankhol, Badaberena, Taptapani and Boden) and ...belong to Mahanadi Geothermal Province, which is an Archean/Pre-Cambrian Geothermal Province. The thermal water discharging from these springs shows moderately acidic to moderately alkaline character (pH: 5.05–8.93) and the temperature ranges from 28 (Boden) to 58 °C (Tarabalo). Total dissolved solids (TDS) also shows a wide variation between 16.9 (Bankhol) and 595 mg/L (Deulajhari). A wide variation in the chemical characteristics of the thermal waters has been observed as they are located in different geological settings. Based on water chemistry, all the thermal springs can broadly be grouped into three water types: Na–Cl, Ca–HCO
3
and Na–HCO
3
. The thermal spring water from Attri, Tarabalo and Deulajhari belongs to Na–Cl water type which is due to the circulation through granitic rocks. Higher concentrations of Cl and F in these thermal waters further suggest limited mixing and longer residence time as compared to the other areas where Ca–HCO
3
and Na–HCO
3
water types were found. Anion variation diagram clearly indicates that the thermal waters from Attri, Tarabalo and Deulajhari are fast ascending and fall in the mature water field; thus, their chemical signatures can be used to determine the reservoir temperature. However, in other areas, water chemistry is shaped by near-surface groundwater mixing processes and thus the chemical geothermometers may not be applicable to determine the reservoir temperature. No appreciable temporal variations have been observed in the water chemistry of the thermal waters.
Despite its location in the “Arid Diagonal” of South America, the Valle de Iglesia contains a number of artesian springs, the most important of which are the Baños Pismanta thermal springs, which ...release water at ~ 45 °C. Despite the scarcity of water resources in the Valle de Iglesia, there have been few attempts to study these springs in any detail. In this study, > 50 springs are described, each characterised by small volcano-like mud structures up to 15 m tall. Hydrogeological and hydrochemical analyses of the groundwater system in the Valle de Iglesia were performed to improve our understanding of the subsurface water flow and of the connections between the subsurface water and the associated systems of faults and springs. Site measurements were made, and the concentrations of the main ions and trace elements were also determined by laboratory analysis of water samples. The samples obtained from the spring were rich in Na–HCO
3
–SO
4
and Na–SO
4
–HCO
3
, but the surface water samples from the Agua Negra River were rich in Ca–SO
4
–HCO
3
. The temperature of the springs was in the range 20–45 °C. Both the temperatures and the ionic ratios are compatible with the presence of a deep hydraulic circulation system. The oxidation of sulphide minerals nearby the magmatic rocks and volcanic edifices causes the mobilisation of arsenic, which accumulates in the groundwater due to the low annual rainfall. The concentrations of arsenic in the spring water samples were therefore higher than the current limit set by the World Health Organisation, meaning that the water is not suitable for human consumption.
Despite its location in the rain shadow of the southern Sierra Nevada, the Panamint Range hosts a complex mountain groundwater system supporting numerous springs which have cultural, historical, and ...ecological importance. The sources of recharge that support these quintessential desert springs remain poorly quantified since very little hydrogeological research has been completed in the Panamint Range. Here we address the following questions: (i) what is the primary source of recharge that supports springs in the Panamint Range (snowmelt or rainfall), (ii) where is the recharge occurring (mountain‐block, mountain‐front, or mountain‐system) and (iii) how much recharge occurs in the Panamint Range? We answer questions (i) and (ii) using stable isotopes measured in spring waters and precipitation, and question (iii) using a chloride mass‐balance approach which is compared to a derivation of the Maxey–Eakin equation. Our dataset of the stable isotopic composition (δ18O and δ2H) of precipitation is short (1.5 years), but analyses on spring water samples indicate that high‐elevation snowmelt is the dominant source of recharge for these springs, accounting for 57 (±9) to 79 (±12) percent of recharge. Recharge from rainfall is small but not insignificant. Mountain‐block recharge is the dominant recharge mechanism. However, two basin springs emerging along the western mountain‐front of the Panamint Range in Panamint Valley appear to be supported by mountain‐front and mountain‐system recharge, while Tule Spring (a basin spring emerging at the terminus of the bajada on the eastern side of the Panamint Range) appears to be supported by mountain‐front recharge. Calculated recharge rates range from 19 mm year−1 (elevations < 1000 mrsl) to 388 mm year−1 (elevations > 1000 mrsl). The average annual recharge is approximately 91 mm year−1 (equivalent to 19.4 percent of total annual precipitation). We infer that the springs in the Panamint Range (and their associated ecosystems) are extremely vulnerable to changes in snow cover associated with climate change. They are heavily dependent on snowmelt recharge from a relatively thin annual snowpack. These findings have important implications for the vulnerability of desert springs worldwide.
The hydrogeological response of desert springs to climate change is controlled by their source of recharge, recharge rate, aquifer volume and aquifer response time. The Panamint Range is located in the rain shadow of the southern Sierra Nevada and the springs in the Panamint Range are heavily dependent upon snowmelt recharge from a relatively thin snowpack. Due to their dependence on recharge from a relatively thin snowpack and inferred shallow groundwater circulation depths, springs in the Panamint Range are likely more vulnerable to the effects of climate change.
Karst aquifers typically have desirable physicochemical properties and can provide an important source of groundwater for drinking. Kiyan karst springs, located in the geological region of the Zagros ...(western Iran), consist of two springs (Keder and Zolal) situated 3 m apart. The water of Zolal spring is always clear, with no turbidity during rainfall or earthquake phenomena, but Keder spring, which also provides drinking water to a city of 10,000 inhabitants (Kiyan city), has very high turbidity in these conditions. This situation disrupts the drinking water supply for about 1 month per year in the study area. The interpretation of discharge time series diagrams, precipitation, and turbidity in different rainfall and earthquake conditions, composite diagrams, and stable isotope concentrations show this study area to be a well-developed karst environment with a highly eroded tectonic zone and large karst conduits along with turbulent water flow. In general, the difference in the behavior of the two springs is related to different paths of water movement through the drainage area. The two springs share the same source of recharge from rainfall and the same initial underground drainage path from the largest sinkhole in the region; although the path of water movement is divided into two branches, with Zolal spring water entering a narrower fault channel. In the Zolal spring pathway, a siphon-shaped reservoir is formed where muddy rainwater settles, so that the water from this spring is clear but has higher concentrations of some ions analyzed here than Keder spring water.
Atmospheric precipitation is the main source of replenishment for large karst springs in the northern China. The extensive spring area and the high heterogeneity and anisotropy of the karst aquifer ...can cause a significant lag in the response of spring water level to precipitation. To explore the response characteristics of different flows of groundwater to precipitation, this study took the Jinan spring area as an example and used time series analysis to investigate the response characteristics of spring to rainfall. This study showed that atmospheric precipitation remains the single most important factor affecting spring discharge at present. According to the characteristics of spring discharge recession, the groundwater flows in the Jinan spring area can be divided into conduit-major fissure flow and diffuse-minor fissure flow. This study examined the response characteristics of different groundwater flows to precipitation through correlation and spectral analyses. The response time of conduit-major fissure flow to precipitation ranged 7–16 days and the duration ranged 12–24 days. The response time of diffuse-minor fissure flow to precipitation ranged 36–56 days, and the duration ranged 1–3 hydrological years. Compared with the karst water system in the southern China, the karst water system in the northern China has a stronger regulating effect. On this basis, this study proposed a correlation and spectral analyses and evaluation method suitable for understanding the dynamics of large karst springs in the northern China.
The energy demand is increasing exponentially on the global scale. To meet this demand, new alternative energy sources are explored, and geothermal energy makes one of the important renewable ...resources. Inherently, the north-eastern states of India have enormous geothermal potential; however, detailed studies evaluating their geothermal potential are quite limited. In view of this, the Garampani and Gelekipung thermal spring clusters of Karbi Anglong district, Assam (India), were evaluated for their geochemical characteristics and geothermal reservoir potential. Water samples from the thermal springs along with groundwater and river water from the surrounding areas were collected seasonally and investigated for various parameters. Thermal waters are NaCl type and show distinct physico-chemical characteristics, as compared to groundwater (Na-HCO
3
) and surface water (Ca-HCO
3
type). The chemistry of thermal water indicates long-term water–rock interactions with the basement rock and does not show an appreciable seasonal variability. The influence of thermal water on groundwater chemistry has been observed during the pre-monsoon season. However, in the post-monsoon season, the delayed monsoonal freshwater influxes seem to diminish any such effect on the groundwater chemistry. The placement of thermal waters in the mature water field of the anion variation diagram confirms their suitability for chemical geothermometry. Silica and cation geothermometry indicates that the geothermal reservoir temperature ranges between 76.3 and 105.8 °C. Thus a low-enthalpy geothermal system exists in the Garampani and Gelekipung thermal spring areas. The radiogenic heat production of the granitic basement rock of the study area was found to range between 2.49 and 8.14 μW/m
3
.
Summary
Microbial communities in hypersaline underground waters derive from ancient organisms trapped within the evaporitic salt crystals and are part of the poorly known subterranean biosphere. ...Here, we characterized the viral and prokaryotic assemblages present in the hypersaline springs that dissolve Triassic‐Keuper evaporite rocks and feed the Añana Salt Valley (Araba/Alava, Basque Country, Spain). Four underground water samples (around 23% total salinity) with different levels of exposure to the open air were analysed by means of microscopy and metagenomics. Cells and viruses in the spring water had lower concentrations than what are normally found in hypersaline environments and seemed to be mostly inactive. Upon exposure to the open air, there was an increase in activity of both cells and viruses as well as a selection of phylotypes. The underground water was inhabited by a rich community harbouring a diverse set of genes coding for retinal binding proteins. A total of 35 viral contigs from 15 to 104 kb, representing partial or total viral genomes, were assembled and their evolutionary changes through the spring system were followed by SNP analysis and metagenomic island tracking. Overall, both the viral and the prokaryotic assemblages changed quickly upon exposure to the open air conditions.
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