Artesian Boreholes Research Articles

The Continental Intercalary in Algeria: Analysis, Survey and Perspectives for Green Agriculture Development

The Northern Sahara Aquifer System (NSAS) is a complex system that includes several aquifers overlying most areas. The Continental Intercalary, also known as the "Albian groundwater" is an aquifer with impressive characteristics. It extends over three countries: Algeria, Tunisia and Libya. Intended for crop irrigation, the boreholes drilled in this Algerian aquifer, the boreholes carried out on this aquifer are artesian in their totality, with flows and pressures reaching in some places considerable values, of the order of 0,4 m3.s-1 for the flow and 3.106 Pa for the pressure. These two parameters are necessary to appreciate the energy potential of the Albian groundwater. A survey of the Continental Intercalary was carried out to study its energy potential. We were able to gather all possible data concerning the boreholes in the Algerian aquifer part. The study covered 295 boreholes that were identified and well documented, spread over 3 regions in southern Algeria. The water from the artesian boreholes in the Albian groundwater is transported to storage basins (for drinking water supply, irrigation and industry) for later use, or distributed directly to users after lowering the temperature of the water in the cooling towers. In these operations, all the hydraulic energy is lost and external energy is required from the electricity grid to meet the needs. The cumulative energy potential of all the boreholes identified has reached the theoretical value of 168GWh/year, the equivalent of 14520 toe (ton of oil equivalent) that are lost annually. Best management of this natural resource will not only enable resilient and sustainable management of the production systems and the environment, but also the energy needed to cool the water, as well as the energy needed for the maintenance of the boreholes and the facilities in the direct neighbourhood.

Artesian conditions in the Chilterns Chalk aquifer (NW of the London Basin) and the implications for surface water–groundwater interactions

AbstractThe Chalk is a principal aquifer which provides an important resource in SE England. For two centuries, it allowed the establishment of a thriving watercress-growing industry, indirectly through diverted stream flow and directly through the drilling of flowing artesian boreholes. The distribution of artesian boreholes across different catchments, suggests a regional control of vertical groundwater flow within the New Pit and Lewes Chalk units. Interrogation of location-specific information points to the confining role of a few key marls within the New Pit Chalk Formation, which can be traced up-catchment to where they naturally outcrop or have been exposed by quarrying. Evidence is found in geophysical logging of a number of boreholes across catchments, confirming a consistent pattern of the spatial distribution of such key markers. When tectonic stress was applied to the various Chalk formations, the marl bands would have reacted, producing more plastic deformation and less fractures in comparison with rigid rock strata. Such a scenario would have created the conditions for secondary aquifer units, giving the Chalk confining or semi-confining hydraulic characteristics on a regional scale. This conceptual understanding helps explain why the river flow response to reductions in groundwater abstraction varies across the flow duration curve.

The revision of Quaternary stratigraphy of the Zrenjanin artesian well borehole profile (Banat, Vojvodina, Serbia)

The geological analysis of artesian borehole material from Sombor, Subotica, and Zrenjanin, was in the first campaign of detailed stratigraphic studies of Vojvodina in 1892-1895. The results of Quaternary stratigraphy from Zrenjanin were published by HalaVaTS more than a decade later (1914). The significance of the Zrenjanin, Sombor, and Subotica artesian well profiles for more than a century is considered the representative local profiles for the Quaternary stratigraphy of Vojvodina recognized by Serbian (Yugoslavian) and Hungarian geologists. Significant changes were after the taxonomical revision of molluscan material and its stratigraphic context, which was done through the excellent work of Krolopp in the 1970-ies. Unfortunately, the mentioned changes were not applied in the studies during the geological surveying of former Yugoslavia. The developments in Quaternary geology, changes in the Quaternary chronostratigraphic scale, and the results shown by this paper enable the lower Pleistocene fluvial deposits to be defined as the Pleistocene Corbicula beds, the Viviparus boeckhi Horizon. The lower Pleistocene at Zrenjanin was documented from 234.54 to 58.36 m depth. The interval between 234.54 and 208.50 m comprises the Upper Paludina ? Viviparus vucotinovici zone, while the Viviparus boeckhi Horizons were identified between 135.18 m and 58.36 m. The interval between 58.36 m and 37.75 m is defined as Pleistocene (lower- and Middle Pleistocene) based on sedimentological and the molluscan record. The interval from 37.75 m to 21.67 m depth was identified as Middle Pleistocene, according to its lithology and the paleontological material. The fluvial sediments? 21.69 m and 7.31 m depths cannot be determined according to the faunistic data; we can only consider them as Pleistocene age. The Holocene sediment and soil horizons ascend to a 2.90 m depth.

Study of soil contamination near R1-Barzina artesian borehole, Vratsa Province

The purpose of the present study is to evaluate the environmental impact of a surface spill of groundwater with high total dissolved solids content by clarifying the extent of contamination in the soil layer near the borehole R1 – Barzina. The overall tendency for limitation of the migration of chloride pollution in the immediate vicinity of the formed surface spill. The fluctuations of the chlorides content in depth indicates the seasonal impact of refreshment by atmospheric waters.

Conditions and processes of precipitation of iron compounds upon discharge of high-mineralized artesian water from artesian borehole R-30, Staro Oryahovo, Bulgaria.

The artesian borehole R-30-Staro Oryahovo with total depth of 1740m gives waters of chlorine-sodium type with a mineralization of 31g/L from formations of Paleogene age. These waters contain high concentrations of iron and because of this, intense precipitation of iron compounds takes place at and around the wellhead. To clarify the ongoing processes, samples of precipitates and overflow water were taken. It was shown that the predominant form of iron in the water before reaching the surface is Fe2+-85-90% and FeCl+-4-11%. The calculated saturation index for a number of Fe2+-containing minerals showed that hydroxides and sulfates of Fe2+ are the possible candidates for sources of iron in the water. The reductive dissolution of wide spread Fe3+-containing minerals (hematite, goethite) was assumed as a possible alternative process releasing Fe2+ into water. At the surface, due to the contacts with the atmospheric oxygen, the environment is sharply changed to oxidizing one thus forming a geochemical barrier and causing mass precipitation of Fe3+ oxides. Simultaneous Fe2+ oxidation, hydrolysis of Fe3+ and co-precipitation with silica and other components are assumed as the major processes causing the formation of low-crystalline Si-containing ferrihydrite or ferrihydrite-like phase. After formation, the precipitated gels due to the processes of aging and continued interaction with the outflowing water have suffered the further change including the formation of goethite. It was shown that due to the intensive precipitation processes, the iron migration to the surface is limited to a very small area and does not affect adjacent agricultural territories with Fe.

MAJOR AND TRACE ELEMENT COMPOSITIONS IN GROUNDWATER OF AWE AREA, PARTS OF THE MIDDLE BENEUE TROUGH-NORTHCENTRAL NIGERIA

A Hydrogeochemical study was carried out in Awe town and environs. The aim of the research was to determine the major, trace and rare earth elements content of the waters and their suitability for domestic, agricultural and industrial uses. Fifteen water sources from hand dug wells, a spring, pond and boreholes were collected and analysed. Inductively Coupled Plasma Mass Spectrophotometer was used to analyse the major cations trace elements and rare earth elements, Ion Chromatography was used to detect the anions and bicarbonate by titration method. In an attempt to determine the species of the trace elements in the waters, modeling was carried out using the WATEQ4F. Generally both the trace and the rare earth elements appear to be low in all the water sources and metal species obtain in the area indicate a dominantly reducing environment. Probable reasons for the low content of the trace elements may be the insolubility of their minerals, complexation , adsorption to clays and some oxides which has immobilized them. Chlorine/Bromine ratios indicate source of saline water (Cl/Br = 1,961) in the free flowing artesian borehole at Old Awe town to be evaporitic in origin. Four groundwater facies types were obtained in the study area; Ca+Mg-HCO3, Na+K-HCO3, NaCl, and Mg-SO4. Physico-chemical parameter, trace elements and their species determined in the area indicate that except for the acidity of the water, over eighty percent of water sources are fresh and soft and therefore good for general domestic uses. Percentage sodium, Sodium Absorbtion Ratios, magnesium hazards and salinity hazards also show that except for three sample locations, all other samples are within values recommended for agricultural purposes. Industries like Rubber manufacturing, sugar processing, textile mills, dairy product manufacturing and paper industry can be situated in the study area.

Quality and Method of Management of Drinking Water in Rural Areas in Benin: Case of Artesian Drills of Dogbo Ahomey in the Borough of Tota, Municipality of Dogbo

The objective of this study is to assess the quality of the artesian borehole water consumed by the population of the village of Dogbo Ahomey in order to prevent pathologies on the populations. Methodology and Results: The household surveys were supplemented by a campaign to analyze the water samples in the laboratory. The samples were analyzed according to the standardized methods of the American Public Health Association (APHAAWWA-WPCF, 1994). A total of twenty (20) physico-chemical parameters and four (04) microbiological parameters were used to assess the quality of the different water samples. The results of the physico-chemical analysis showed that the water samples studied present values that are below the standards recommended by the WHO and by the Beninese standards for the quality of drinking water (Standards, 2001). From a microbiological analysis point of view, of the four samples studied, two show strong pollution by germs. This could be a significant health risk for households who take water from these sources to meet their needs.

Targeted isolation based on metagenome‐assembled genomes reveals a phylogenetically distinct group of thermophilic spirochetes from deep biosphere

Most microorganisms from deep terrestrial subsurface remain yet uncultured. Recent achievements in recovery of metagenome-assembled genomes (MAG) provide clues for improving cultivation via metabolic reconstructions and other genomic characteristics. Here we report the isolation in pure culture of a thermophilic spirochete with the use of MAGs binned from metagenomes of the deep (>2 km) aquifers broached by two artesian boreholes in Western Siberia. The organism constitutes a minor share in the aquifer microbial community and could not be cultivated by traditional techniques. The obtained two pure culture isolates along with three bacteria identified by MAGs represent a novel family-level lineage in the order Brevinematales. Based on genomic and phenotypic characteristics the novel spirochete is proposed to be classified as Longinema margulisiae gen. nov., sp. nov. within a novel family, Longinemaceae fam. nov. Both cultivated strains, NST and N5R, are anaerobic hemoorganoheterotrophes growing by fermentation of starch and a few sugars. They can form recalcitrant round bodies under unfavourable growth conditions, which survive up to 15 min at 95°C and can revert to the original helical cells. We suggest that the round bodies may facilitate global distribution of this lineage, detected from molecular signaturesand colonization of subsurface environments.

Sulfate Reduction in Underground Horizons of a Flooded Coal Mine in Kuzbass

Although dissimilatory sulfate reduction (DSR) is an important microbial process in subterranean aquifers, its geochemical consequences in this ecosystem remain insufficiently studied. The absence of data on the process rate under in situ conditions prevents quantitative estimation of the sulfur reservoir. This research is aimed at investigation of microbial sulfate reduction in subterranean aquifers associated with the Severnaya coal mine in Kuzbass. Water samples were collected from an artesian borehole broaching the underground horizons of the flooded mine. During over 10 years of sampling the water temperature fluctuated within a narrow range (10–13°C); the water was anoxic (–112 to –174 mV) and contained up to 6 mg/L sulfide. Analysis by high-throughput sequencing of the 16S rRNA genes showed that sulfur-oxidizing bacteria Sulfurovum, Sulfuricurvum, Sulfurospirillum, and Thiothrix predominated in the community. No phylotypes with known ability to carry out DSR were detected. Measurement of sulfate reduction rates with $${\text{Na}}_{{\text{2}}}^{{{\text{35}}}}{\text{S}}{{{\text{O}}}_{{\text{4}}}},$$ showed the process to be relatively active, resulting in up to 178 g of reduced sulfur per year at the borehole discharge. Two organisms representing minor components of the community, a psychrophilic and acidophilic Desulfomicrobium sp. DI and a moderately thermophilic Desulfotomaculum LL1, were isolated in pure culture by varying the cultivation condition in a bioreactor. These members of the “rare biosphere” may be responsible for production of reduced sulfur species, which are used by a diverse and numerous sulfur-oxidizing community.

Reassessing Groundwater Potentials and Subsurface water Hydrochemistry in a Tropical Anambra Basin, Southeastern Nigeria

This review presented a detailed re-assessment of the hydrogeology and hydrochemistry of the Tropical Anambra Basin. It identified and discussed the major geological formations and their groundwater potentials. The geological examination showed that the Ajali Formation is confined in places forming an artesian condition; the potentials of this aquifer decline in the western basin due to a decrease in thickness. The sandstone associates of the Nsukka Formation are aquiferous and have produced high-pressure artesian boreholes along the Oji River. The Imo Shale is characterized by permeability stability all over much of the intermediate unit. The Bende-Ameki aquifer has a lesser amount of groundwater when equated to other formations; the geologic characteristics do not produce favorable hydrogeological conditions for groundwater occurrence. The stratigraphical and structural framework suggested the presence of an efficient throughflow in the basin. Based on physical and chemical parameters of water quality, the basin holds water of acceptable quality. While there are considerable investigations on the hydrogeology and hydrochemistry, studies are short of analysis of the hydrogeochemical evolution of groundwater, water quality index, heavy metals pollution index as well as total hazard quotient. Suitability of groundwater based on agricultural water quality indices (e.g. SAR) is also salient. Therefore, future studies should address these owing to increasing dependence on groundwater.

Defining hydrogeology of the Gohar-Zamin open pit mine, Iran: a case study in a hard-rock aquifer

Gol-Gohar iron ore mines, with a reserve of about 1.1 billion tons, constitute the largest iron ore mine complex in Iran. Pit number 3 (Gohar-Zamin mine) has the largest reserve of ore among the others. Pit advancement toward deeper parts of the aquifer has increased groundwater inflow into the pit. During exploratory drillings in Gohar-Zamin mine, some of the boreholes became artesian. The water outflow from these boreholes has high salinity (classified as brine) and high pressure of a gas with an unknown origin. A conceptual model of groundwater flow was established using the available evidence and information. The prepared model revealed that there is a minimum of three aquifers, two alluvial aquifers (with electrical conductivity (EC) of 4,000–37,000 μS/cm) and one hard-rock aquifer (EC of 91,800–169,000 μS/cm) in the study area, with different lithological and hydrochemical characteristics. The brine outflow from the artesian boreholes originated from the hard-rock aquifer, which is a confined and high-pressure system without active recharge, i.e. an unsustainable resource. There is no hydraulic connection between the pit mine and the playa, located 13 km north of the mine, through the hard-rock aquifer, and the brine in the hard-rock aquifer is fossil water or has a metamorphic origin. The present study shows that the groundwater in the hard-rock aquifer is entrapped between fault planes without any hydraulic connection with overlying aquifers. Further, the results suggest that numerical groundwater flow models can only be successfully applied to the alluvial aquifer.

The natural mineral water aquifer of Amarante

The presentation includes the geological, tectonic and geomorphological characterization, the hydrogeological model, the hydrochemistry and the boreholes of mineral aquifer of Amarante. The natural mineral water of Amarante is sulphurous and is captured by two artesian boreholes. The fault system of Tâmega river valley is the conducting channel and the Padronelo-Amarante fault is the trap that causes the emergencies of natural mineral water.

Evaluation of the impact by deep artesian boreholes on fresh ground waters in the terrace of Kamchiya River

The area of Kamchiya River’s inflow into the Black Sea has an important role not only as a natural landmark, but also as a leading factor for the national economy. It has been subjected for many years to oil and gas exploration, as well as to extraction of deep, highly mineralized waters containing chemical elements of industrial value. There are currently only few of the artesian wells related to these activities in the area. Outflowing water has very high mineralization (over 50 g/l). It is chlorine-sodium type and has extremely high concentrations of some components. They have formed small salt ponds around the wells, whose water and salt balance are controlled by the evaporated and infiltrated in depth water quantities. The abrupt change in the thermodynamic conditions in the porous part of the wells favours the processes of sedimentation and deposition of a substance that partially refreshes the leaking surface water and limits the possibilities for infiltration of highly mineralized waters. Salt infiltration causes enhanced local salinization of the soils and fresh groundwater accumulation in the present-day sediments of the Kamchiya River. An assessment of both the dimensions and extent of salinization in the area of the deep wells is made by applying hydrochemical and geoelectrical survey.

Differences between groundwater fauna in shallow and in deep intergranular aquifers as an indication of different characteristics of habitats and hydraulic connections

<p>The fauna in the hyporheic zones of rivers has been relatively well studied but that from the phreatic zone remains comparatively unknown and there are few investigations into deeper intergranular aquifers (over 30 m in depth) due to technical difficulties. Two shallow boreholes of 29 m depth and two deep boreholes of 100 m depth, both near Ljubljana (Slovenia), were sampled more than 30 times between 14 January 2008 and 3 March 2009. On each occasion 14.4 to 18.0 m<sup>3</sup> of water were abstracted using a high-capacity pump, then filtered by means of a plankton net with a mesh size of 60 µm. Organisms larger than 2 mm were damaged by the pump rotors, but their identification was still possible, while smaller representatives of the Copepoda (Crustacea) passed the rotors without damage. A near-by artesian borehole was sampled on 6 occasions. Water chemistry, physical properties and faunal composition analyses were carried out for each borehole. A total of 32 taxa, 24 of which were stygobites, were identified. Copepoda alone were represented by 16 species, 15 of which were stygobites. The shallow boreholes differ from the deep boreholes in their higher temperatures and higher concentrations of K<sup>+</sup>, Na<sup>+</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup> and SO<sub>4</sub><sup>2-</sup> ions. The copepod communities in samples from the shallow boreholes differ sharply from those from the deep boreholes. There were also clear differences between shallow boreholes in two aquifers located a few kilometres apart, in physical and chemical characteristics as well as in fauna composition. Taxa with different ecological affinities, collected from groundwater, are indicators of hydraulic connections between different parts of an aquifer as well as of communication between surface and subsurface water bodies. The present study suggests that subterranean fauna, as well as epigean fauna, can provide effective support for classical dye/salt tracing experiments.</p>

High fluoride drinking water in Gokwe, northwest Zimbabwe

More than 200 million people worldwide are exposed to excessive fluoride in drinking water. According to the World Health Organization, the optimal concentration range of fluoride in drinking water is 0.5 to 1.5 mg/L. Above this range, populations may contract dental fluorosis or, in severe cases, crippling skeletal fluorosis. In the Gokwe area in NW Zimbabwe, where drinking water contains up to 11 mg/L fluoride, fluorosis prevalence has previously been estimated at 62%. This paper investigates the water quality of 126 water sources in Gokwe (58 pumped boreholes, 15 flowing artesian boreholes, 46 wells and 7 streams). The water chemistry, determined from high performance ion chromatography and field measurements, showed that the water source types exhibit significantly different (P < 0.05) concentrations of F−, Cl−, Na+, K+, Ca2+, Mg2+, temperatures, pH and conductivity values. Thirty-five (28%) of the 126 water sources (18 pumped boreholes, 15 artesian boreholes, one well and one stream) contained F− > 1.5 mg/L, indicating that fluoride contamination in the area is a characteristic of deeper groundwater, possibly due to its interactions with the potentially fluoridic coaly and carbonaceous materials of the Lower Karoo Aquifer at depth. The plausibility of providing alternative low fluoride water, and defluoridation, should be investigated.

Endocrine and metabolic impacts of warming aquatic habitats: differential responses between recently isolated populations of a eurythermal desert pupfish.

Temperatures of inland aquatic habitats are increasing with climate change, and understanding how fishes respond physiologically to thermal stress will be crucial for identifying species most susceptible to these changes. Desert fishes may be particularly vulnerable to rising temperatures because many species occupy only a fraction of their historical range and occur in habitats with already high temperatures. Here, we examined endocrine and metabolic responses to elevated temperature in Amargosa pupfish, Cyprinodon nevadensis amargosae. We studied C. n. amargosae from two habitats with distinct thermal conditions: the Amargosa River, which experiences diurnally and seasonally variable temperatures (0.2-40°C); and Tecopa Bore, a spring and marsh fed by hot groundwater (47.5°C) from an artesian borehole. These allopatric populations differ in morphology, and prior evidence suggests that temperature might contribute to these differences via altered thyroid hormone (TH) regulation of morphological development. Here, we document variation in hepatic iodothyronine deiodinase type 2 (dio2) and type 3 (dio3) and TH receptor β (trβ) gene transcript abundance between the Amargosa River and Tecopa Bore wild populations. Fish from these populations acclimated to 24 or 34°C retained differences in hepatic dio2, dio3 and trβ mRNAs and also varied in transcripts encoding the TH membrane transporters monocarboxylate transporter 8 (mct8) and organic anion-transporting protein 1c1 (oatp1c1). Tecopa Bore pupfish also exhibited higher dio2 and trβ mRNA levels in skeletal muscle relative to Amargosa River fish. Muscle citrate synthase activity was lower at 34°C for both populations, whereas lactate dehydrogenase activity and lactate dehydrogenase A-chain (ldhA) transcripts were both higher and 3,5,3'-triiodothryonine responsive in Tecopa Bore pupfish only. These findings reveal that local population variation and thermal experience interact to shape how pupfish respond to elevated temperatures, and point to the need to consider such interactions in management actions for desert fishes under a changing climate.

Assessment of the physical environment of epigean invertebrates in a unique habitat: the case of a karst sulfidic spring, Slovenia

AbstractA well‐fissured and faulted karst area at the Žveplenica sulfidic spring created suitable conditions for epigean copepods. Their presence in sulfidic water is a rare phenomenon. To understand the conditions related to sulfidic habitats in the region, two additional springs were analysed: the Studenec karst spring and the Sovra artesian borehole, which contains dissolved sulfide. Water temperature, chemistry and the stable isotopes of oxygen and hydrogen show that the Sovra borehole water has a different origin and history to that of the Žveplenica and Studenec springs water, which is derived from local precipitation. The low slope of the δ18O–δ2H regression line for the Žveplenica spring indicates a mixing of local precipitation water with geothermal sulfidic water that may explain the presence of live copepods. These harpacticoid and cyclopoid copepods must have survived anoxia and high sulfide for some time. The mean transit time for Žveplenica spring cannot be defined precisely from the available data, although the degree of attenuation of the isotopic signal indicates mean transit times of about 1·0 to 1·5 years. Sites similar to Žveplenica spring should be carefully analysed because not only do they provide insights into biodiversity but they also represent an ecotone between the anoxic/oxic and high/low sulfide of these karst waters. Copepods in similar geological settings can be used as additional parameters to evaluate conditions in subsurface sulfidic habitats and their spatial connectivity and responses to hydrological events. Copyright © 2014 John Wiley & Sons, Ltd.

用研究示例诊断标绘分析南非桌山山脉组自流含水层

Parameter estimates of artesian aquifers where piezometric head is above ground level are largely made through free-flowing and recovery tests. The straight-line method proposed by Jacob-Lohman is often used for interpretation of flow rate measured at flowing artesian boreholes. However, the approach fails to interpret the free-flowing test data from two artesian boreholes in the fractured-rock aquifer in Table Mountain Group (TMG) of South Africa. The diagnostic plot method using the reciprocal rate derivative is adapted to evaluate the artesian aquifer properties. The variation of the derivative helps not only identify flow regimes and discern the boundary conditions, but also facilitates conceptualization of the aquifer system and selection of an appropriate model for data interpretation later on. Test data from two free-flowing tests conducted in different sites in TMG are analysed using the diagnostic plot method. Based on the results, conceptual models and appropriate approaches are developed to evaluate the aquifer properties. The advantages and limitations of using the diagnostic plot method on free-flowing test data are discussed.

A hydraulic test device for free-flowing artesian boreholes with a case study in Table Mountain Group (TMG) aquifers, South Africa

Accurate parameter estimation for aquifers is very challenging, particularly for artesian aquifers in which the potentiometric surface is above ground level. A common approach to parameter estimation for artesian aquifers is to make use of free-flowing and recovery tests. However, such aquifer tests on artesian boreholes are seldom carried out due to lack of an appropriate device readily available for data collection. This paper describes a hydraulic test device for recording flow rate, pressure, EC and pH measurements using an ultrasonic flowmeter, pressure transmitter, EC and pH meters. A procedure to set up the device in the field is outlined. To test the device, an artesian borehole in the Table Mountain Group (TMG) aquifers of South Africa was chosen as a case study, where the device was applied to measure and record flow rate and pressure of the aquifer, as well as EC and pH. Compared with previous free-flowing test data measured manually, the flow data captured by the device was accurate and reliable, and can be utilised to estimate the hydraulic properties of an artesian aquifer. The advantages and disadvantages of the device are discussed, followed by suggestions for improvement. Given that a large number of flowing artesian boreholes are present in the TMG area in which the pressure head of the aquifer is often above ground level, the applicability of the device presented is likely to be widespread. With due improvement of the test device, its wider application in similar conditions, e.g. to artesian holes in the Karoo, would be expected in future.Keywords: flowing artesian borehole, hydraulic test device, free-flowing test, TMG aquifers, data capture

The algal community at an ecocline of a cold sulphidic spring (Sovra artesian borehole, Slovenia)

The physicochemical parameters of the sulphide spring water from a 500 m deep artesian borehole in Sovra Valley (Slovenia) are stable, with very little variation: temperature, 9.2 ± 0.0 °C; pH 7.70 ± 0.11; specific electrical conductivity, 777 ± 8 μS/cm; and dissolved oxygen, 0.19 ± 0.11 mg/l. The water from the borehole is hard, rich in sulphates, and has a notable concentration of sulphide, while it is low in chlorides. Communities of phototrophs were analysed at the oxygenic ecocline at the outflow from the borehole, and from further downstream. Caloneis tenuis, Frustulla vulgaris, Gomphonema sp., Navicula radiosa, Oscillatoria sp., and Tribonema vulgare successfully thrive exclusively at the outflow from the borehole under sub-optimum conditions for the majority of phototrophs. Downstream from the borehole, where the hydrogen sulphide degasses, autotrophic biofilms were dominated by different diatoms. The Bray–Curtis similarity index confirms the distinctive phototrophic communities along the oxygenic ecocline downstream from the sulphidic spring. The sulphidic ecocline downstream from the spring is indicative of the composition of phototrophic communities, as some species appear only downstream from the spring. An ecocline downstream from the borehole of the sulphidic spring was reflected also in the bacterial indicator groups. This study brings novel insights to the limited knowledge in the field of oxygenic phototrophy related to sulphidic springs.