Tritium Tracer Research Articles

Long-term spatiotemporal variation in groundwater recharge in the highly irrigated semi-arid region of India: The intertwined relationship between climate variability and anthropogenic activities

Quantifying groundwater recharge in semi-arid regions is crucial for water resource management and ensuring food security. This study estimates groundwater recharge from the water table fluctuation (WTF) and tritium tracer methods and examines the impact of irrigated agriculture in Telangana, which experiences semi-arid climatic conditions. The mean recharge over the study period was 176 mm using the Water Table Fluctuation (WTF) method and 118 mm using the tritium tracer method. However, it experiences a significant decrease during drought years. Our analysis reveals that approximately 15% of the average annual precipitation (960 mm), subject to interannual variations, contributes to natural recharge. The contribution exhibits significant spatiotemporal variations influenced by both natural and anthropogenic factors. The Empirical Orthogonal Function (EOF) analyses show a significantly high correlation (0.80) between precipitation and groundwater storage. Since the hard rock crystalline aquifers comprises about 85% of the study area, the storage capacity of saprolite layers and developed fracture systems primarily limit recharge. Despite ample rainfall in two consecutive years, the recharge is significantly low in the second year. However, a drought in the previous year, followed by favorable rainfall in the current year, tends to increase recharge. Over the past three decades, the area irrigated with groundwater has increased 2.5 times, which has affected groundwater recharge rates. This study provides insights into groundwater dynamics and its association with climate variability and human activities, especially in the crystalline hard rock aquifer systems under semi-arid conditions. Understanding the interplay between hydrogeological, climate, and anthropogenic factors is crucial for implementing effective water conservation measures in water stress areas and formulating regional groundwater management policies.

Tritium and trees: A bomb peak perspective on soil water dynamics in semi-arid apple orchards

Understanding the relationship between agroforest age and soil water dynamics is crucial for effective land and water resources management. However, the complexities of these dynamics, such as soil water recharge and depletion, hamper in-depth understanding, particularly in water-scarce regions. In this study, we examined soil water recharge and depletion in relation to the stand age of apple trees, a widely planted and representative deep-rooted agroforest, over four years in a semi-arid region on China’s Loess Plateau (CLP). We collected soil cores to >20 m depth from four apple orchards (referred to as ‘agroforests’) with variable stand ages (established in 2008, 2005, 1998, and 1994). For comparison, we selected adjacent cropland as land use prior to agroforestry practices (‘control’). We measured soil water content and tritium distributions to model soil water dynamics and estimate water ages across different soil profiles. Our results show that recharge amounts (and depths) in shallow soils were 298.4 mm (7 m), 303.4 mm (6.6 m), 300.6 mm (5.4 m), and 483.1 mm (7.6 m), whereas deep soils had net depletions of 111.1 mm, 391.9 mm, 192.8 mm, and 108.9 mm for AP2008, AP2005, AP1998, and AP1994, respectively. The tritium peak depths, which indicate the 1963 bomb peak depth, significantly differed between agroforested and non-agroforested plots. In particular, agroforestation reduced the seepage velocity of soil water over 20 years. Furthermore, our tritium tracer water age model suggests that the age of transpired deep soil water exceeded 200 years in the oldest orchard. These findings highlight a complex interaction between newly infiltrated water and existing water, possibly due to variations in soil pore size distributions. The results of this study offer valuable insights into the ecohydrological impacts of agroforestation on the CLP and in similar climatic regions.

Understanding Shallow Basaltic Aquifer System Near West Coast of Maharashtra, India

Two-Dimensional (2D) Electrical Resistivity Tomography (ERT) and geophysical logging and injected tritium tracer studies with hydrogeological tests were carried out at selected location in an area of 5 km2 near the coastal region of Tarapur, Thane district, Maharashtra. The area is in basaltic terrain, overlain by thin cap of alluvium formation and receives an annual rainfall of about 2000 mm. An integrated investigation method was adopted to delineate the subsurface lithological variations, understand the existing aquifer system up to 25 m depth, evaluate aquifer properties, recharge potential and also to monitor the groundwater flow characteristics. The investigation results showed a variable thickness of weathered zone of 1-3 m, existence of two basalt flows, low vertical natural recharge, high transmissivity, high hydraulic conductivity and high groundwater flow rates. The results also depicted that a combination of hydrogeological tests along with resistivity and tracer investigation is an effective tool in mapping and characterizing the shallow potential groundwater aquifer zone in Deccan traps. The integrated study carried out in the coastal area provided detailed subsurface information useful for planning specific water conservation strategies for sustainable groundwater supply. Keywords: Deccan Traps, ERT, Tritium Tracer, Recharge, Groundwater Flow

Transport Upscaling in Highly Heterogeneous Aquifers and the Prediction of Tracer Dispersion at the MADE Site

AbstractWe present an upscaled Lagrangian approach to predict the plume evolution in highly heterogeneous aquifers. The model is parameterized by transport‐independent characteristics such as the statistics of hydraulic conductivity and the Eulerian flow speed. It can be conditioned on the tracer properties and flow data at the injection region. Thus, the model is transferable to different solutes and hydraulic conditions. It captures the large‐scale non‐Gaussian features for the evolution of the longitudinal mass distribution observed for the bromide and tritium tracer plumes at the Macrodispersion Experiment (MADE) site (Columbus, Mississippi, USA), which are characterized by a slow moving peak and pronounced forward tailing. These large‐scale features are explained by advective tracer propagation due to a broad distribution of spatially persistent Eulerian flow speeds as a result of spatial variability in hydraulic conductivity.

Development of Tritium Tracer Doped Liquid Fuel Target for Inertial Confinement Fusion at the Gekko XII-LFEX Facility

In inertial confinement fusion (ICF), a fuel target containing deuterium and tritium is used. In recent ICF experiments on the Gekko XII LFEX facility at the Institute of Laser Engineering at Osaka University (ILE-Osaka), a target comprised of a polystyrene capsule filled with D2O liquid and a solution of X-ray tracer materials, such as copper, titanium, or chlorine, was developed. In this study, an additional T2O doping technique by which tritium can be mixed uniformly has been developed. The T2O is synthesized by T2 gas using a CuO oxidation catalyst. The T2O is agglutinated by cold trap and transferred to a target cell in which a D2O-solution-filled target is placed. Because polystyrene is slightly permeable for T2O and D2O, D2O is exchanged by T2O and completely mixed. Thus, a uniform tritium-doped ICF target with various materials can be fabricated. The T2O synthesizing and doping system is developed and tested using H2 as a cold run. The H2O is successfully doped to a D2O prefilled target at approximately 50% doping. This scheme will be utilized in future fast ignition experiments at ILE-Osaka.

Tritium tracer Injection test at Wayang Windu Geothermal Field, West Java, Indonesia

Abstact The Wayang Windu Geothermal Field (WWGF), with an installed capacity of 227 MWe (Units 1 & 2), has been in production for eighteen (18) years. Currently, there are twenty-nine (29) active production wells, located mainly in the northern and central areas of the field (Gambung-Wayang). About 100 kg/s of condensate and 60 kg/s of brine are disposed of (by gravity) to three (3) injection wells in the southern (Windu) area, with less than 5% recharge to the reservoir (NDSA tracer test). A tracer injection test was conducted in 2014 and 2016 to better understand the vertical connectivity between the deep brine and the steam cap reservoir in the northern Gambung area. The tracer used was tritium in water or tritiated water (HTO). Around 20 ml (equal to 20–23 Ci) of tritium was injected using capillary tubing to the depth of deep liquid feed zones in two wells, MBE-5 and WWS-1, located in the central area of the field. Tracer returns were monitored mostly in dry steam wells in the northern Gambung area. Interpretation of the tracer return profiles included 1) the tracer breakthrough time; 2) time of maximum concentration, which reflects the average fluid velocity; 3) the width of the tracer ‘pulse’, which reflects the flow path dispersion; and 4) tracer recovery as a function of time. Three typical tracers return profiles were observed (fast, intermediate, and slow); the shape of the tracer ‘pulse’ was consistent with a single flow-path. Monitoring wells WWQ-5 and WWT-2 showed the highest mass recovery and the fastest breakthrough times. Total mass breakthrough calculated from the tritium tracer (using TRINV calculation) was about 5%, which is similar to results from earlier liquid tracer tests (NDSA), albeit for a different area of the field (laterally and vertically). Despite the low percentage of mass breakthrough, the data may provide some insight for assessing possible future central-deep infield-injection strategy. The different tracer returns profiles observed in the monitoring wells may contribute to refining the structural interpretation and identifying preferred fluid pathways. Overall, the results of the tritium tracer test provide some insight about the heterogeneity of the fracture network that controls how the tracers are dispersed.

Understanding water circulation with tritium tracer in the Tural-Rajwadi geothermal area, India

This study investigates the water circulation using tritium measurements in local precipitation, shallow dug wells and thermal springs of the Tural-Rajwadi area, which is one of the potentially productive geothermal areas in India. In the study area, the estimation of tritium-tracer mean transit times (MTTs) in the mixed thermal waters is lacking despite available tritium measurements in 1977 and 2013 and carbon-14 measurements in 2008. As a direct tracer of water movement, tritium radioisotope with a half-life of 12.32 years has been applied to estimate transit times of young waters, especially in the mixture of young and old water components, and tritium sampling was conducted in 2017 to reduce the ambiguity involved with tritium interpretation. For the study area, two scaling factors of latitude effect are established for anthropogenic and ambient tritium levels in precipitation to obtain continuous time-series of tritium in monthly precipitation from the Tokyo area. Annual weighted tritium concentrations in recharge are estimated as a difference between monthly precipitation and evaporation data and are utilized as the tritium input in the convolution integral to obtain tritium-tracer MTTs. Using the exponential piston-flow model (EPM), the representative MTT of shallow groundwater is estimated to be 12.5 ± 4.5 years at TDW-1 well and 15.5 ± 8.5 years at RDW-1 well and uncertainties in MTT due to the EPM ratio and scaling factor are found to be low. For two thermal springs, simulated tritium concentrations of the young groundwater in mixed thermal waters produce unique MTT solutions resulting in MTT of 28.0 ± 12.0 years for THS-1 spring and of 29.5 ± 12.5 years for RHS-1 spring and scaling factor uncertainties are lower than EPM ratio uncertainties, which could be further reduced by an additional tritium sampling. Combining carbon-14 concentrations of 2008 samples with tritium-tracer, the old water MTTs of THS-1 and RHS-1 thermal springs equal to 13500 ± 1500 years and 6900 ± 900 years, respectively, and aggregate MTTs of mixed water are 9189 ± 1023 years for THS-1 spring and 4701 ± 616 years for RHS-1 spring. Using these MTTs with the effective porosity values of 0.01 and 0.03 result in the geothermal reservoir volume of the Tural-Rajwadi area to vary between 347.3 ± 23.3 km3 and 115.8 ± 15.4 km3, respectively, and these volumes could be used to estimate the recharge area with geothermal system depth obtained from deep drilling. In conclusions, we highlight that the environmental tritium provides important information on water circulation in the Tural-Rajwadi area and similar tritium-tracer investigations of young and mixed waters could be conducted in other geothermal areas in Asia.

Chemical forms of hydrogen desorbed by permeation through pure iron and oxide dispersion strengthened steels

To clarify factors controlling variation of chemical forms of hydrogen desorbed by permeation phenomena through the oxide dispersion strengthened ferritic (ODS) steels, permeation behaviors of hydrogen through pure alpha iron (Fe) and the ODS steel into a pure argon (Ar) gas atmosphere have been examined by hydrogen permeation experiments with a tritium tracer technique. Difference of chemical forms of hydrogen desorbed by permeation through pure Fe and the ODS steel was explained by oxygen potential at a downstream side which was determined by an amount of hydrogen supplied by permeation and a moisture content in the Ar gas atmosphere at a certain temperature. Due to very high stability of chromium oxides formed on the ODS steels, most of hydrogen desorbed as a hydrogen gas molecular form into the Ar gas atmosphere in the present experimental temperatures ranging from 303 K to 623 K.

Effects of shot-peening on permeation and retention behaviors of hydrogen in alpha iron

Effects of the shot-peening on hydrogen permeation and retention behaviors were examined by applying tritium tracer techniques to the gas-driven hydrogen permeation experiments. Hydrogen permeability in shot-peened iron was reduced by a factor of ten in comparison with the as-received iron at lower temperatures of 298 K and 453 K. The effects were disappeared at higher temperatures than 473 K. Hydrogen was trapped at least two trapping sites induced by the shot-peening treatment. The amount of trapped hydrogen in the shot-peened surface was three times larger than that in the normal surface of the as-received iron.

1-5.トリチウムトレーサー法を用いた石炭の水素移動性の評価(Session(1)石炭利用)

1-5.トリチウムトレーサー法を用いた石炭の水素移動性の評価(Session(1)石炭利用)

6.トリチウムトレーサー法を用いた石炭液化反応条件下でのテトラリンの水素移動性評価 : 硫化水素および水の添加効果

6.トリチウムトレーサー法を用いた石炭液化反応条件下でのテトラリンの水素移動性評価 : 硫化水素および水の添加効果

Agricultural Drainage Filters. I. Filter Hydro-Physical Properties and Tracer Transport

Drainage filters using porous granular material constitute new innovative technologies for remediating phosphorus (P) from agricultural tile drainage water. In drainage filters where convective velocities are often high, we hypothesize that intragranular diffusion may affect solute transport depending on filter characteristics and flow rate. This was investigated for six drainage filter materials (Leca, Filtralite-P®, granulated limestone, crushed seashells, calcined diatomite earth (CDE), and a poorly ordered Fe oxide aggregate (CFH)) conducting a tritium (3H2O) tracer experiment at low (0.26 cm h−1), medium (23 cm h−1), and high (41 cm h−1) flux densities. The filter materials differed widely with respect to grain-size distribution (D 50 from 1.6 to 3.3 mm), uniformity coefficient (1.7 to 2.2), particle density (1.75 to 2.76 g cm−3), bulk density (0.34 to 1.46 g cm−3), and water-filled porosity (0.39 to 0.73 cm3 cm−3). Measurements of specific surface area (SSA) included both SSABET and SSAEGME to ensure inclusion of the intragranular microporosity, not accounted by N2-BET. SSA varied widely across methods and allowed the differentiation of filters according to the significance of the intragranular porosity. Tritium transport varied from approximately equilibrium transport at all flow rates in Leca, Filtralite-P®, and limestone, to progressive non-equilibrium transport as flow rate increased in Seashells, CDE, and CFH. In general, the filter materials were highly variable in hydro-physical properties. Filters with (approximately) equilibrium transport were, however, all characterized by low specific surface areas. The non-equilibrium transport was explained by an intragranular diffusion in filters with larger specific surface area (Seashells, CDE, and CFH).

Mapping Lithology and Assessing Recharge Characteristics in a Granitic Hard Rock Aquifer: Inference from 2D Resistivity, Induced Polarization, Tracer and Moisture Measurements

Abstract: Two dimensional Electrical Resistivity Tomography (ERT) investigation along with Time Domain Induced Polarization (TDIP) investigation covering 1.6 km line were carried out at 3 natural recharge sites in a overexploited groundwater granite watershed, situated in a semi arid region in the state of Telangana, India. At these sites, shallow and/or deep moisture influx measurements were also carried out using injected tritium tracer and neutron moisture probe. The watershed is covered by sandy loam to silt loam soil, receives an average annual rainfall of 620 mm with the pre monsoon groundwater level ranging from 8m to 29m bgl. The spot investigations were done to assess and understand the recharge process and groundwater potential in terms of resistivity/conductivity and moisture characteristics of the subsurface rock formation. The measured and 2D inverted resistivity models shows soil, highly weathered and moderately weathered zones up to a depth of 22m followed by semi-weathered and massive granites up to the maximum depth of 78m. The resistivity values of the soil and shallow weathered zones varying between ~5-50 Ohm.m up to a depth of 12m. The large variation in resistivity values of the soil and weathered zone is probably indicative of large variation in the moisture potential. The resistivity models clearly mapped the granitic hard rock structure in the depth range of 22 – 78m, which has a significant resistivity contrast (~1500-11000 Ohm.m) with respect to the overlying semi weathered layers. The modeled 2D resistivity data at a site in two perpendicular directions shows similar geological structure and geoelectric layers. The TDIP dataset shows insignificant chargeability variations (1-7 mV/V) up to the investigated depth of 78m, which probably indicates low to moderate moisture and groundwater potential in the vadoze and saturated zones of the aquifer. The experimental investigations provide scope for assessing dynamic recharge and groundwater potential at selected sites in an overexploited granite watershed in the present geological context.

Behavior of Tritium Permeation Induced by Water Corrosion of Alpha Iron around Room Temperature

In order to understand behaviors of hydrogen uptake and permeation in pure (αiron (αFe) during water corrosion around room temperature, hydrogen permeation experiments for a αFe membrane have been conducted by means of tritium tracer techniques. Hydrogen produced by water corrosion of αFe is trapped and/or blocked in/by product oxide layers to delay hydrogen uptake in αFe for a moment. However, the oxide layers do not work as a sufficient barrier for hydrogen uptake. Some of hydrogen dissolved in αFe could normally diffuse and permeate through the αFe bulk. Assuming hydrogen dissolution at the water/Fe interface proportional to the square root of the hydrogen pressure (Sieverts’ law), the partial hydrogen pressure were estimated to be 0.7, 5.0 and 9.5 kPa at 303, 323 and 348 K, respectively.

Effects of Soil Compaction and Organic Carbon Content on Preferential Flow in Loamy Field Soils

Preferential flow and transport through macropores affect plant water use efficiency and enhance leaching of agrochemicals and the transport of colloids, thereby increasing the risk for contamination of groundwater resources. The effects of soil compaction, expressed in terms of bulk density (BD), and organic carbon (OC) content on preferential flow and transport were investigated using 150 undisturbed soil cores sampled from 15 × 15–m grids on two field sites. Both fields had loamy textures, but one site had significantly higher OC content. Leaching experiments were conducted in each core by applying a constant irrigation rate of 10 mm h with a pulse application of tritium tracer. Five percent tritium mass arrival times and apparent dispersivities were derived from each of the tracer breakthrough curves and correlated with texture, OC content, and BD to assess the spatial distribution of preferential flow and transport across the investigated fields.Soils from both fields showed strong positive correlations between BD and preferential flow. Interestingly, the relationships between BD and tracer transport characteristics were markedly different for the two fields, although the relationship between BD and macroporosity was nearly identical. The difference was likely caused by the higher contents of fines and OC at one of the fields leading to stronger aggregation, smaller matrix permeability, and a more pronounced pipe-like pore system with well-aligned macropores.

Determination of hydrogen diffusion and permeation coefficients in pure copper at near room temperature by means of tritium tracer techniques

• We have applied a tritium tracer technique for gaseous hydrogen permeation in Cu. • We have succeeded to get reliable data for hydrogen permeability in Cu. • Diffusivity are bending downward from the extrapolation of higher temperature. • Diffusivity are influenced by initial surface contamination which is removed by hydrogen. Copper (Cu) and its alloys are candidate materials for heat sinks or cooling-tubes in a fusion reactor. Hence their tritium retention and permeation are very important safety concerns. Most data for diffusion and permeation of hydrogen in Cu so far available have been limited for rather higher temperatures and data for lower temperatures, in particular, for near room temperature (RT) are scarce. We have applied a tritium tracer technique for gaseous hydrogen permeation in pure Cu at near RT and succeeded to get reliable data for hydrogen permeation coefficients given by Φ = (2.8 ± 0.4) × 10 −6 exp(−85 ± 2(kJ/mol)/RT), mol m −1 s −1 Pa −1/2 , which is reliable in very wide temperature range from 300 K to 1000 K. However, diffusion coefficients determined by the time-lag method are bending downward from the extrapolation of higher temperature data and are influenced by initial surface contamination which is removed by hydrogen loading.

Vadose zone tritium tracer test to estimate aquifer recharge from irrigated areas

AbstractEnvironmental tracers, such as tritium, have generally been used to estimate aquifer recharge under natural conditions. A tritium tracer test is presented for estimating recharge under semi‐arid and irrigated conditions. The test was performed along 429 days (June 2007–August 2008) on an experimental plot located in SE Spain with drip irrigation and annual row crops (rotation of lettuce and melon), in which common agricultural practices were followed in open air. Tritiated water was sprinkled (simulated rainfall) over the plot, soil cores were taken at different depths and a liquid scintillation analyzer was used to measure tritium concentration in soil water samples. Tritium transport, as liquid or vapor phase, was simulated with the one‐dimensional numerical code SOLVEG. Simulations show that the crop water use was below potential levels, despite regular irrigation. Continuous high water content in soil promoted a great impact of rainfall events on the aquifer recharge. The results obtained from tritium tracer test have been compared with other independent recharge assessment, soil water balance method, to evaluate the reliability of the first one. Total recharge from tracer test was 476 mm for the October 2007–September 2008 period versus 561 mm from soil water balance method for the same period, which represents 37.1% and 43.7% of the applied water (1284 mm, irrigation + precipitation), respectively. Copyright © 2012 John Wiley & Sons, Ltd.

Application of Tritium Tracer Technique to Determination of Hydrogen Diffusion Coefficients and Permeation Rate near Room Temperature for Tungsten

Applying a tritium tracer technique, we have investigated hydrogen plasma driven permeation (PDP) through tungsten (W) near room temperature. The technique was confirmed to give reliable data on diffusion and permeation coefficients of pure W for gas driven permeation (GDP), and then it was applied to observe PDP in W near room temperature. It was found that PDP in earlier phase was controlled by diffusion giving reliable diffusion coefficients. Taking literature data at higher temperatures and present ones near room temperature determined from PDP into account, we have proposed new diffusion coefficientsDUpper limit = (3.8±0.4)x10-7 exp ((-39.8±1.5) (kJ/mol)/RT), m2s-1. (1)The activation energy for permeation determined by PDP was similar to that by GDP. The extrapolation of the present data to higher temperature agreed well with Frauenfelder’s data, suggesting the activation energy of around 65 kJ/mol for permeation is quite reasonable. However prolonged measurements resulted in significant reduction of PDP. The cause of the reduction was attributed to the increase of reemission owing to surface cleaning and/or roughening by incidence of energetic hydrogen.

Room-Temperature Reactor Packed with Hydrophobic Catalysts for the Oxidation of Hydrogen Isotopes Released in a Nuclear Facility

A room-temperature reactor packed with hydrophobic catalysts for the oxidation of hydrogen isotopes released in a nuclear facility will contribute to nuclear safety. The inorganic-based hydrophobic Pt catalyst named H1P has been developed especially for efficient oxidation over a wide concentration range of hydrogen isotopes at room temperature, even in the presence of saturated water vapor. The overall reaction rate constant for hydrogen oxidation with the H1P catalyst in a flow-through system using a tritium tracer was determined as a function of space velocity, hydrogen concentration in carriers, temperature of the catalyst, and water vapor concentration in carriers. The overall reaction rate constant for the H1P catalyst in the range near room temperature was considerably larger than that for the traditionally applied Pt/Al2O3 catalyst. Moreover, the decrease in reaction rate for H1P in the presence of saturated water vapor was slight compared with the reaction rate in the absence of water vapor due to the excellent hydrophobic performance of H1P. Oxidation reaction on the catalyst surface is the rate-controlling step in the range near room temperature and the rate-controlling step is shifted to diffusion in a catalyst substratum above 313K due to its fine porosity. The overall reaction rate constant in the range near room temperature was dependent on the space velocity and hydrogen concentration in carriers. The overall reaction rate constants in the range of 1;000=T greater than 3.2 correlated to k overall[s−1] = 5.59 × 107 × SV[h−1] × exp (−67.7 [kJ/mol]/RgT), where the space velocity range was from 600 to 7,200 h−1.

Hydrogen behavior near surface regions in Mo and W studied by tritium tracer technique

Tritium tracer techniques are applied to observe behavior of hydrogen (tritium (T)) in near surface regions of Mo and W loaded by gaseous absorption (GAS) and a glow discharge (GDC). GDC produces blisters on both Mo and W surfaces and Tritium Auto-RadioGraph (TARG) showed the thickness of blister skins is larger than the escaping depth of T β-electrons, around 1μm. For GAS specimens, T evolution is likely controlled by diffusion giving diffusion coefficients of, DMo=1.5×10-7exp-41kJ/molRTm2s-1 DW=4.3×10-9exp-38kJ/molRTm2s-1 at 273–323K. GDC specimens show much smaller diffusion coefficients with higher activation energies and T release continues very long, suggesting T release from blisters.