Tritium Values Research Articles

Tritium Behavior from Vine to Wine

The hydrogen radioactive isotope, tritium, not only reflects seasonal variation in precipitation but also variations on a local level. To use this radioisotope in authentication and geographical indication procedures, the tritium levels in vines, grapes, and wine were measured in two forms: (1) tissue-free water tritium (TFWT), measured in the free water of the plant or the aqueous phase of the wine; (2) organically bound tritium (OBT), measured in the organic part of the plant or wine (as ethanol). This paper presents the tritium behavior in vines from May to October and in the wine produced from harvested grapes for both tritium forms (TFWT and OBT) in connection with environmental tritium concentrations in air and precipitations during the 2019–2023 vegetation periods near the Râmnicu Vâlcea city. If the tritium of tissue-free water was influenced by precipitation and air humidity during the harvest period, the organically bound tritium recorded a maximum level with a delay of 1–2 months compared with tritium’s seasonal variation in precipitation and air. The tritium values of early mean in precipitation and ethanol from wine were approximately an average value of 11 TU for all 5 years of observations.

Geochemical and Isotopic Characteristics of the Emir Geothermal Waters in Kula Area, Western Anatolia

In this study, we investigate chemical and isotopic characteristics of thermal waters of the Emir geothermal field in the Kula region, which hosts the youngest volcanism in Turkey. Studied thermal waters with temperature and electrical conductivity values of 21–63 °C and 3840 to 5210 μS/cm are of Na–HCO3 type and have neutral character. δ18O and δD of thermal waters are − 9.40 to − 8.41‰ and − 64.16 to − 56.38‰ (VSMOW) and indicate a meteoric source with local recharge. Tritium values of thermal waters in the Emir geothermal field are mostly < 1 TU signifying a deep circulation. Positive δ13C values (1.32–4.46‰ VPDB) imply that carbon is derived dominantly from marine limestone and dominantly from endogenic CO2. δ18O and δ34S of dissolved sulfate yield that marine limestone is the source of sulfur in thermal waters, which are partly affected by sulfide oxidation and bacterial reduction processes. At discharge temperatures, Emir thermal waters are oversaturated with respect to albite, aragonite, calcite, α-cristobalite, dolomite, gibbsite, illite, K-feldspar, kaolinite, muscovite and quartz but undersaturated for anhydrite and wairakite. The activity diagrams suggest that high Na+ and K+ concentrations in waters are attributed to dissolution of muscovite, K-feldspar and albite. Chemical and isotopic compositions of the Emir thermal waters are controlled by a combination of processes including water–rock interaction, dissolution/precipitation and ion exchange. Various chemical and isotopic geothermometers applied to the thermal waters yielded reservoir temperatures in the range of 80–125 °C. Paleo-temperatures estimated from δ18O values of travertines and thermal waters (isotope fractionation) are consistent with modern discharge temperatures.

Hydrochemical systematics and isotope (δ18O, δD and 3H) variations of aquifer system of southern Bengal Basin: implications for groundwater pollution.

Hydrogeological, hydrochemical and isotopic traits of the groundwater in the Quaternary aquifer system in an urban-periurban locality within and encircling the Kolkata-Howrah twin city in the south Bengal Basin have been synthesised to explain the present- and paleo-hydrological processes, surface and groundwater interaction and mixing dynamics of contamination of groundwater. Rock-weathering, evaporation, ion-exchange and active mineral dissolution are the key processes commanding the groundwater chemistry. Freshwater flushing from the recharge zones had thinned the entrapped sea water which has generated the present-day brackish water by a non-uniform fusion. The best-fit line of the plots of δD and δ18O of groundwater samples displays a slope lower than that of local meteoric water line (LMWL) and global meteoric water line (GMWL) which hints that isotopic constitution of the groundwater of the present area is primarily formed by evaporation before or in the recharging process. A wide range of δ18O values in groundwater suggests that these waters are not blended enough toremove dissimilarities in isotope configuration of recharge water. This also suggests that many groundwaters are a result of mixing of present-day recharge and an older integrant recharged under previously cooler climatic conditions. The groundwater samples are more depleted of oxygen at the shallower level. The depleted samples cluster around the Tolly's nala (canal) where upper aquitard is missing or < 10-m thick. The tritium values range between 0.70 and 15.02 which indicate the occurrence of 'sub-modern', 'a mix of modern and sub-modern water' and 'modern water'. It indicates mingling of isotope-depleted water from the Hugli River by means of Tolly's canal with relatively less-depleted groundwater of Kolkata's late Pleistocene aquifer. The tritium values and Cl/Br ratio of groundwater samples adjoining Tolly's canal and elsewhere refer the direct infiltration of 'modern wastewater and freshwater' which mixes with the 'sub-modern water' in the aquifer system.

Environmental Tracers Tritium 3H and SF6 Used to Improve Knowledge of Groundwater Sustainability of a Crystalline Rock Island Aquifer of Tobago, West Indies

Understanding the residence time, flow velocities, and storage volumes in fractured rock aquifers is essential for assessing the sustainable use of groundwater in island aquifer systems. Environmental tracers such as tritium (3H) and sulfur hexafluoride (SF6) that enter the aquifer systems through natural hydrological processes are effectively used to quantify the “apparent age” of young groundwater (&lt;60 years) to calculate these aquifer characteristics. The island of Tobago is predominantly a fractured rock aquifer system that contains groundwater sub-basins that produce 100–1000% more than their calculated recharge. In this study, we analyzed ten samples from groundwater wells throughout the island for environmental tracers to establish the “apparent age” of the groundwater. We then estimated the active flux and storage volume of the aquifer. The 3H results of ten wells throughout the island range between 0.02 and 0.60 TU. The groundwater samples to the south of the island possess more pre-modern groundwater ages (older ages) than samples in the north of the island. These tritium values reveal age ranges between 18 and 60–plus years. This finding suggests that fractures create flow paths oriented towards the southern parts of the basin that enable the transport of groundwater across significant topographic boundaries and watershed divides. Additionally, the data may support that southern wells are connected to isolated old sources of groundwater. SF6 values range between 0.91 and 7.97 (part per trillion volume) with an interpreted age range between 18 and 39 years. Both tracers support the original hypothesis that longer residence time waters are located south of the island except for three SF6 samples which are believed to be affected by “excess air”.

Using Tritium Isotope in Groundwater to Estimate the Reservoir Capacity at Erbil, Northern Iraq

Tritium is a radioactive isotope of hydrogen in water molecule can be applied in tracer studies to estimate water residence time. The tritium values of the groundwater in Erbil and the reservoir's capacity were the main subjects of this investigation. Three sub-basins, including, Kapran (720 km2), Central (1315 km2), and Bashtapa (625 km2) constructs Erbil City's groundwater basin. 27 groundwater samples from three sub-basins were taken for oxygen-18, tritium analysis and measurement of electrical conductivity. Tritium values divided the groundwater reservoirs into three possible groups: pre-bomb groundwaters that has ages older than 70 years due to lower tritium values, contaminated groundwater and mixture between young and old groundwaters. It is adequate to suppose that there were several substantial subsurface retention reservoirs in Dashty-Hawler basin. For instance, if two wells from the Kapan sub-basin were used as a point of reference, well No. 1 in Kalak region would have a tritium value of 1.7 ± 0.72 TU having groundwater that was approximately 16.2 years old. In contrast, the well No. 6 at Grd-Jutyar has a lower tritium value equal to 0.72 ± 0.68 TU indicating a greater residence time of 31.6 years. These two wells have differing reservoir sizes, and well No. 6 has a longer retention basin to store groundwater than well No. 1 According to these findings, younger groundwater and smaller retention basins were indicated by greater tritium levels, whereas older groundwater and larger retention basins were noted by lower tritium levels.

Hydrochemical and isotopic characteristics of the Lodwar Alluvial Aquifer System (LAAS) in Northwestern Kenya and implications for sustainable groundwater use in dryland urban areas

Groundwater is a crucial resource for dryland regions such as this, where surface water resources are limited and unreliable. This paper presents a study of the Lodwar Alluvial Aquifer System (LAAS) in northwestern Kenya and its hydrochemical and isotopic characteristics, with the goal of understanding how to sustainably manage the groundwater system. As a result, the paper focuses on elucidating the hydrogeochemical and river-groundwater interaction (using environmental isotopes and major ion chemistry) of an aquifer that is located in the north-western dryland of Kenya. The study utilised environmental isotopes of oxygen-18 (18O), deuterium (2H), and tritium (3H) as tracers for establishing recharge sources and origin of groundwater. A sampling campaign involving 112 water samples was conducted to establish isotopic compositions of rain, spring, surface water (rivers, scoop holes, dams and lake) and groundwater at the peak of the wet season in May 2018. The tritium values in the study area ranged from 1.1 to 2.4 TU. Considering the median values of δ18O and δ2H in surface water and groundwater samples, four clusters emerge based on the degree of enrichment; Cluster 1 comprises the lake water (δ18O = +6.01, δ2H = +41.9); Cluster 2 is the Turkwel and Kawalase river water with slightly positive relative to VSMOW and with different δ2H values (+7.6‰ versus −9.8‰). The third cluster is the groundwater of the Shallow Alluvial Aquifer (SAA) and the Deep Aquifer (DA) (δ18O = −0.96‰ and −0.70‰; and δ2H = +0.4‰ and +0.6‰, respectively). The last cluster comprises the most isotope-depleted waters of water pans, scoop holes, Intermediate Aquifer (IA) and Turkana Grit Shall Aquifer (TGSA) with median values ranging from −2.87‰ to −2.48‰ for δ18O and −8.6‰ and −16.4‰ for δ2H. While the SAA is mainly recharge by the Turkwel River, a relationship is observed between the values deuterium in the Kawalase (−9.6‰ VSMOW) and IA (−8.6‰ VSMOW). Understanding recharge sources and aquifer vulnerability of similar strategic aquifers helps scientists appropriately advise policymakers and the water community who develop sustainable water use, aquifer protection and conservation strategies. In addition, the study contributes scientific evidence of isotopic compositions of groundwater in the Horn of Africa. Furthermore, the evidence of surface water-groundwater interaction presents a case of a fragile dryland ecosystem. Future work will involve the installation of piezometers in strategic aquifer zones to monitor groundwater levels in relation to river gauging data to quantify the amount of recharge and establish the impacts of rainfall variability in the upstream catchment.

Temporal variability of precipitation isotopes in Damascus, Syria — implications for regional climate change

Records of stable isotopes (2H and 18O), deuterium excess (d-excess) and tritium (3H) values in precipitation (P) during 1990–2022, together with long-term time series (1919–2022) of air temperature (T) and P-amount values at the Damascus station, were analysed to explore the seasonal and annual variability patterns of those parameters in P and assess the vulnerability to climate change in this area. Variation of the annual average air T values over the period 1919–1969 shows an increase gradient of ≈ + 0.1 °C/decade. However, a remarkable much higher gradient (+ 0.64 °C/decade) is calculated for the period 1990–2022. The average P-amount value calculated for the last three decades (≈185 mm) was lower by ≈28 mm, compared to the value (≈213 mm), relative to the reference period (1919–1969). This significant decline in the annual P-amount value by ≈11–13%, accompanied by an annual heating of 0.2–0.6 °C/decade in the annual air T, is likely the result of the climate change affecting this area. The linear relationships between annual average δ18O and annual average δ2H values versus time over the period 1990–2019 indicate increased gradients in both stable isotopes (≈0.3–0.5‰ and ≈1.1–3.2‰ per decade for δ18O and δ2H, respectively), accompanied with a decrease gradient of ≈0.9–1.1‰ per decade in d-excess values. Variability of annual 3H concentrations towards low levels (< 6 TU) during the later years strongly suggests the return back towards the cosmogenic production of this radioisotope in the upper atmosphere. Information gained from this work would offer new insights to improve the understanding of the temporal variability of P isotopes and assess the risks associated with climate change on the natural water resources in the Eastern Mediterranean region.

Towards the first direct measurement of the dynamic viscosity of gaseous tritium at cryogenic temperatures

Accurate values for the viscosity of the radioactive hydrogen isotope tritium (T2) at cryogenic temperatures are unavailable. Values for tritium found in literature are based on extrapolation by mass ratios as well as an empirical factor derived from hydrogen (H2) and deuterium (D2) viscosity measurements, or classical kinetic theory which does not handle quantum effects. Accurate data of the tritium viscosity will help to improve the modelling of the viscosity of diatomic molecules and can be used as a test of their interaction potentials.With this contribution we report a major step towards a fully tritium and cryogenic temperature compatible setup for the accurate measurement of the viscosity of gases, using a spinning rotor gauge (SRG) at the Tritium Laboratory Karlsruhe. After calibration with helium, measurements with hydrogen and deuterium conducted at room temperature agree with literature values within 2%. The performance at liquid nitrogen (LN2) temperature has been successfully demonstrated with a second setup in a liquid nitrogen bath. Again after calibration with helium at LN2 temperature, the viscosities of H2 and D2 were determined and are in agreement with literature to about 2%.

Isotopic and Chemical Tracing for Residence Time and Recharge Mechanisms of Groundwater under Semi-Arid Climate: Case from Rif Mountains (Northern Morocco)

Karstic aquifers play an important role for drinking and irrigation supply in Morocco. However, in some areas, a deeper understanding is needed in order to improve their sustainable management under global changes. Our study, based on chemical and isotopic investigation of 67 groundwater samples from the karst aquifer in the Rif Mountains, provides crucial information about the principal factors and processes influencing groundwater recharge and residence time. The δ18O and δ2H isotopic values indicate that the recharge is derived from meteoric water at high, intermediate, and low elevations for Lakraa Mountain, North of Lao River, and Haouz and Dersa Mountain aquifers, respectively. All samples show an isotopic signature from Atlantic Ocean except for those from the Lakraa Mountain aquifer, which shows Mediterranean Sea influence. Groundwater age determined by radiocarbon dating using the IAEA model indicates that the ages range from modern to 1460 years. This short residence time is consistent with the detectable tritium values (&gt;2.7 TU) measured in groundwater. These values are similar to those of precipitation at the nearest GNIP stations of Gibraltar and Fez-Saiss, situated around 100 km north and 250 km south of the study area, respectively. This evidence indicates that groundwater in the Rif Mountains contains modern recharge (&lt;60 years), testifying to significant renewability and the vulnerability of the hydrological system to climate variability and human activities. The results also indicate the efficiency of isotopic tracing in mountainous springs and would be helpful to decision makers for water in this karstic zone.

Influence of climate on groundwater fluoride in different climatic domains in a hard rock terrain of Sri Lanka: implications to community health.

Health risks associated with excessive intake of fluoride through drinking water are one of the geoenvironmental health problems observed in many parts of the world, mainly in countries of the humid tropical belt, including Sri Lanka. Fluoride-related health problems are widespread in the dry climatic region compared to the wet climatic zone of Sri Lanka. The potential health risks of fluoride for communities in a river basin which drains through two climatic zones, viz. wet and dry zones, were investigated in this study. Sixty-three groundwater samples were collected from wells in the Walawe river basin during pre- and post-monsoon periods. From collected samples, ten selected samples were analyzed for their tritium (3H) levels to find out the approximate resident time of groundwater. In the river basin, the dry zone segment is characterized by elevated levels of fluoride (> 1.0mg/L) in groundwater. Groundwater fluoride in the region was primarily of geogenic origin. The tritium values showed older groundwater contained higher fluoride levels, showing a increased dissolution of fluoride-bearing minerals. The hazard quotient (HQfluoride) showed that about 45% ofpre- and 55%of post-monsoon groundwater samples in the dry zone area were unsuitable for drinking purposes for school children who are vulnerable to non-carcinogenic risks and dental fluorosis. This study emphasizes the need for continuous water quality monitoring and mitigation measures to ensure the health of residents.

Correlation of Tritium Concentration in Rainwater with Cosmic Rays: Preliminary Results

The Radiochronology Center has been established in 1999 as a member of the Horizontal Laboratories network of the University of Ioannina. Recently it has added to its activities the development of a tritium measurements laboratory as part of the Radiochronology Center. The laboratory is equipped with a super low level background liquid scintillation counter, which is capable to measure very low concentrations of tritium for applications in radioprotection, dating and hydrology.For the aims of the present continuing study rainwater samples are collected monthly. Each sample is distilled and then it is passed through an electrolysis process to increase the tritium concentration. Five mL of the enriched sample are mixed with 15 mL of a scintillation cocktail, specially designed for tritium measurements and its beta activity is measured for 200 min. The LLD of tritium in the samples is estimated 3 Bq/L or 27 TU.Our preliminary results show that, during the measuring period tritium concentration increased with time. The tritium values are correlated with the cosmic ray neutron flux data at ground level, available for Greece in the same period. The measured tritium concentrations in rainwater, which range from 36 ± 8 to 64 ± 8 TU, may be used for local hydrology studies.

Constraining the mean transit time (MTT) of relatively modern thermal waters in Deccan volcanic geothermal area, India using tritium tracer

Constraining the mean transit time (MTT) of thermal waters is essential to understand the sustainability and renewal rate of geothermal systems. In this study, tritium concentrations of samples from five thermal water manifestations, three shallow groundwater wells (dug wells) and one deep groundwater (borehole) are analysed at regular time intervals for three years to estimate the MTT of the thermal and non-thermal waters in the Deccan Volcanic geothermal province by using lumped parameter models. The tritium concentrations of the thermal waters are found to vary between 0.77 and 2.77 TU (±0.0.23 TU at 1σ) which are lower than those of the shallow non-thermal groundwater (5.4–7.18 TU) (±0.40 TU at 1σ) whereas the tritium value for the deep groundwater ranges between 2.30 and 2.78 TU (±0.27 TU at 1σ). Among different lumped parameter models, PFM (piston flow model), EMM (exponential mixing model) and EPM (exponential piston flow model) are used to estimate the MTT of the groundwater and thermal waters in the study area. The historical records of weighted mean concentration of tritium in precipitation at the nearby Tural-Rajwadi geothermal area is taken as input function in the modelling procedure. The PFM and EMM models represent the lower and upper case of the EPM model mixing, respectively whereas the values obtained from the EPM models provide the actual range of mean transit times. The overall uncertainty in the MTT estimation has also been computed. The MTT of the younger fraction of the thermal waters in Ganeshpuri thermal water (HS-1) and Akloli thermal water (HS-7) are found to be 70 ± 5 and 90 ± 14 years old respectively. The MTT of both the shallow groundwater (DW-1 and DW-3) samples is estimated to be ~1.5 years whereas the MTT of the deep groundwater (BH-1) is 39 ± 6 years. Thermal springs in this area undergo mixing with non-thermal water during its ascent towards the surface as a result binary mixing model has been applied to find the MTT of the mixed thermal spring. The aggregate MTT of HS-1 turns out to be 7860 ± 870 years. This study of MTT estimation can be used for accessing the sustainability and renewability of these thermal waters compared to other thermal areas in Deccan volcanic region.

Tritium in Laurentian Great Lakes surface waters

A basin-wide water quality survey for the radionuclide tritium during 2017 and 2019 provides an overview of levels in Great Lakes surface waters. All data, together with those from similar basin-wide surveys since the early 1990s, are included in the Supplemental Material. Values of tritium are lowest in Lake Superior and are highest within a region of northwestern Lake Ontario, as well as locally near a known source in Lake Huron. Twenty-year trends show declines in all of the lakes, and this is consistent with the decline in fallout from past nuclear weapons testing, the major source of tritium to the lakes. Longer-term trends, developed using values from the literature, demonstrate a marked overall reduction in tritium values since maxima in the late 1960s, with a slowing rate of decline in the most recent decade. As atmospheric fallout is reduced, the relative importance of other sources is increasing. Known releases, primarily from nuclear generating stations using heavy water, could therefore drive any future changes in Great Lakes tritium levels.

An Assessment of Aquifer Potential in and around a Proposed Well Field Area near Madunaghat, Chattogram Using Isotopic Techniques

The study was undertaken for understanding the potential of deep aquifers as a source of safe drinking water and for assessing the status of groundwater aquifer near Madunaghat area, Chattogram. The specific issues are salinity, interconnectivity of the shallow and deep aquifers, mixing of groundwater with the adjacent Halda river water, recharge condition and groundwater age. The isotopic data suggest that most of the groundwater results from a mixture between recent recharge and an older component recharge under climatic conditions cooler than at present. The interconnectivity between shallow aquifers and river waters are mostly found in the line wells installed particularly in shallow depth (16 m) close to Halda river as evidenced from the similar tritium values of sampled line well water with that of the Halda river water. The groundwater in Madunaghat well field area is not affected by salinity, as it is evidenced by higher values of Na/Cl ratio of the groundwater samples compared to the sea water fresh water mixing line. The geochemistry of intermediate and deep groundwater is dominated by Na-Mg-HCO3 and Na-HCO3 type waters. Even the relationship between chloride and oxygen-18 (Cl-δ18O) depicts that the waters from the deep, intermediate and shallow wells do not fall on the seawater mixing line. The Carbon-14 contents of intermediate to deep groundwater samples vary from 16.2 to 59.3 pMC indicating the residence time in the range of 4300 to 15,000 years BP, i.e., the sourced water recharged the aquifers a long time ago. The intermediate and deep wells have water with arsenic concentrations less than the detection limit of 3.0 μg/L. Only a few shallow wells have arsenic concentrations greater than the detection limit varying from 13.7 - 47.4 μg/L, which is less than the DoE permissible limit (50 μg/L) implying that the groundwater at Madunaghat area is not affected by Arsenic contamination.

Tritium as a hydrological tracer in Mediterranean precipitation events

Abstract. Climate models are in need of improved constraints for water vapor transport in the atmosphere, and tritium can serve as a powerful tracer in the hydrological cycle. Although the general principles of tritium distribution and transfer processes within and between the various hydrological compartments are known, variation on short timescales and aspects of altitude dependence are still under debate. To address questions regarding tritium sources, sinks, and transfer processes, the sampling of individual precipitation events in Corte on the island of Corsica in the Mediterranean Sea was performed between April 2017 and April 2018. Tritium concentrations of 46 event samples were compared to their moisture origin and corresponding air mass history. Air mass back-trajectories were generated from the novel high-resolution ERA5 dataset from the ECMWF (European Centre for Medium-Range Weather Forecasts). Geographical source regions with similar tritium concentrations were predefined using generally known tritium distribution patterns, such as the “continental effect”, and from data records derived at long-term measurement stations of tritium in precipitation across the working area. Our model-derived source region tritium concentrations agreed well with annual mean station values. Moisture that originated from continental Europe and the Atlantic Ocean was most distinct regarding tritium concentrations with values up to 8.8 TU (tritium units) and near 0 TU, respectively. The seasonality of tritium values ranged from 1.6 TU in January to 10.1 TU in May, and they exhibited well-known elevated concentrations in spring and early summer due to increased stratosphere–troposphere exchange. However, this pattern was interrupted by extreme events. The average altitude of trajectories was correlated with the tritium concentrations in precipitation, especially in spring and early summer and if outlier values of extreme tritium concentrations were excluded. However, in combination with the trajectory information, these outlier values proved to be valuable for improving the comprehension of tritium movement in the atmosphere. Our work shows how event-based tritium research can advance the understanding of its distribution in the atmosphere.

Role of Quaternary glacial-outburst megaflood paleochannel deposits in a basalt-dominated aquifer system in the West Plains area of eastern Washington, USA

Approximately 2 km2 of sand- and gravel-rich Pleistocene glacial-outburst megaflood sediment has accumulated in a series of five subparallel paleochannels that are an important component of a basalt-dominated aquifer system on the semiarid, ~450-km2 West Plains area. Located near Spokane, Washington (USA), the West Plains paleochannel deposits have been used for artificial storage and recovery wells and for planned and passive stormwater disposal in this rapidly growing area. Recent recognition of perfluorooctanoic acid contamination and excessive drawdowns have led to the closure of multiple municipal wells on the West Plains, highlighting the challenges of developing a sustainable groundwater supply in this complex aquifer system. Geologic and hydrogeologic data, from more than 1,400 water-well reports, surface exposures, existing groundwater geochemistry reports, and modeling, reveal the interconnections between the paleochannel deposits and surrounding basalt flows in three dimensions (3D). Initially incised into the Miocene Columbia River Basalt and excavated by Pleistocene glacial-outburst megaflooding, the West Plains paleochannels are projected in unprecedented 3D. This study’s modeled interactions between the more highly hydraulically conductive (100×) paleochannel sedimentary deposits and surrounding basalt beds provide insight into 14C ages and tritium values that had been measured previously. Sediment-filled closed depressions at the bases of the paleochannels, which are features likely formed by turbulent bursts (‘kolks’) during peak megaflood flows, are potentially promising groundwater storage sites. However, because of the relatively higher permeability of the unconfined paleochannel deposits, the closed depressions also are potential conduits for infiltration of contamination to deeper parts of the aquifer system.

Application of environmental isotope techniques for determining the origin and mechanisms of recharge of the Rashche Spring

This study is focused on the groundwater system of the Rashche Spring which serves as the main source of drinking water for the City of Skopje, located at the foot of the widely karstified Zeden massif. Investigations were made to define the mechanisms of groundwater recharge and its residence time. This was done using isotope tracers including 1H, 2H, 3H, and 18O in water samples from the local hydrological cycle, as well as noble gases for the application of 3H/3He dating method. A linear regression model of stable isotope data of precipitation samples resulted in the best-fit equation of δ2H = 7.46 · δ18O + 9.56, and shows a δ2H dependence from the altitude of precipitation formation with a gradient of − 3.06‰/100 m. Local precipitation, surface waters and Rashche Spring water showed a relatively narrow range of tritium values of 5 ± 1 TU, whereas the deep artesian water from Polog Valley yielded very low tritium contents (< 0.5 TU). In addition to this, we applied a one-cell mixing model with three inlet components (precipitation, Vardar River and deep artesian water). Numerical simulation based on tritium data of local precipitation and based on a defined ratio of the inlet components allowed calculation of the MRT (mean residence time) of 30 years for the water of the aquifer located below the Zeden Massif which is recharging the Rashche Spring. Using the 3H/3He dating method, the ages of observed ground water including the water from the Rashche Spring were determined showing a good agreement with the calculated MRT. This result also provides substantial information about the vulnerability of this water resource and the necessity for better conservation of the investigated local surface and groundwater.

The effect of geochemical processes on groundwater in the Velenje coal basin, Slovenia: insights from mineralogy, trace elements and isotopes signatures

This study investigated the mineralogical and isotopic composition of groundwater and precipitation to identify and constrain geochemical processes within stacked Pliocene and Triassic aquifers in the Velenje coal basin. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopic analysis revealed that suspended matter in the Pliocene aquifer consists of feldspars and quartz, while dolomite, calcite and feldspars are present in the aquifer dewatering Triassic strata. The concentrations of trace elements in Triassic and Pliocene aquifers range from highest to lowest Zn > Fe > Ni > Al > Ba > Mn > B>Li > Mo > As with the majority of trace element concentrations below international drinking water health guidelines. Multivariate principal component analysis indicated that concentrations of Mn, Ba, Eu, Cs, Y, Li and T, pH, conductivity and dissolved oxygen in samples were the best chemical parameter for distinguishing the two aquifers. A significant positive correlation (p < 0.05) was found between Ni, Mn, Co, Zn, As and Mo. Groundwater in the Pliocene aquifer likely has an external source of carbon based on the δ13CCO2 values (− 12.3 to − 3.6‰). The groundwater also has detectable levels of dissolved methane with isotopic values (− 77.7 to − 51.4‰ δ13CCH4; − 247 to − 162‰ δ2HCH4) consistent with microbial methanogenesis. The groundwater in the Triassic aquifer has tritium values (up to 4.1 TU 3H) characteristic of modern recharge (< 50 years), while the lack of detectable 3H (0 TU) in the Pliocene aquifer is consistent with longer residence times.

Hydrogeochemical controls on aquifers of northwestern Illinois’ Driftless Area, USA

Groundwater in the Driftless Area of northwestern Illinois is a very hard Ca–Mg-bicarbonate-type water that reflects the dolomite aquifer material in this karst region. Groundwater in shallow aquifers has a short residence time and is susceptible to surface-borne contaminants. Deeper aquifers have distinct chemistry indicating longer flowpaths, most clearly indicated by low tritium values and elevated potassium and fluoride concentrations. Thirty water samples were collected from springs from across Jo Daviess County in northwestern Illinois between 2015 and 2016. The groundwater samples collected from what were initially identified as springs were found to be of two types: (1) natural springs that are stratigraphically controlled and discharging from crevices and bedding planes, especially where the underlying Galena Dolomite or overlying Silurian dolomite aquifer intersects the Maquoketa Shale; and (2) abandoned flowing-artesian wells, often with no identifiable well casing at the surface, that had been mistaken for springs. Background concentrations of eight water-quality parameters were calculated to determine pre-settlement and present-day background thresholds. The background concentrations, overall chemical compositions, tritium concentrations, and F/Cl and K/Cl ratios were used to characterize and group groundwater within the study area. The results of this investigation combined with recent work by the authors [Panno et al. (IL State Geological Survey Circular 586, 2017)] were used to determine the geologic, hydrogeologic, and geochemical controls on springs in this part of the Driftless Area. The results of this investigation revealed the susceptibility of the Galena Dolomite and Silurian dolomite aquifers to surface-borne contaminants. In addition, this work has developed a means, using ion ratios and spring location relative to bedrock geology to identify discharge from abandoned wells.

An Integrated Isotope-Geochemical Approach to Characterize a Medium Enthalpy Geothermal System in India

The Manuguru geothermal area, situated in the Telangana state, is one of the least explored geothermal fields in India. In this study, the chemical characteristics of the groundwater (thermal and non-thermal waters) are investigated to elucidate the source of the solutes dissolved in the water and to determine the approximate residence time of the thermal waters. The major hydrogeochemical processes controlling the groundwater geochemistry have been deciphered using multivariate statistical analysis, conventional graphical plots and geochemical modelling (PHREEQC). Geochemically different groundwater clusters (bicarbonate type, bicarbonate–chloride type and chloride type) can clearly be identified from the chemometric analysis, i.e. PCA and HCA. Thermal waters are mostly Na–HCO3 type having low EC and TDS compared to non-thermal groundwaters. Silicate weathering and ion exchange mainly contribute to the dissolved ion budget in the groundwater of the study area. The carbon isotopic composition of DIC (δ13C) points to silicate weathering with soil CO2 coming from C3 type of plants. Stable isotopes (δ18O, δ2H) data confirm the meteoric origin of the thermal waters with no oxygen-18 shift. The low tritium values of the thermal water samples reveal the long circulation time (> 50 years) of the recharging waters. Radiocarbon dating (14C) shows that the approximate residence time of the thermal waters ranges from 9952 to 18,663 year BP (before present).