Distribution of uranium in groundwaters of Bathinda and Mansa districts of Punjab,India: inferences from an isotope hydrochemical study

This paper presents the isotope hydrochemical results of groundwaters from southwest Punjab for assessing the uranium contamination and evaluating the factors leading to elevated uranium concentration. A total of 35 samples covering shallow and deep zones were collected for hydrochemistry and isotopes. Uranium concentration ranges between 2.3 and 357 µg L^?1 and 66% of the samples are contaminated. Both shallow and deep zones show U contamination but high incidences are noticed in shallow zone. Hydrochemical correlations infer geological sources rather than anthropogenic sources responsible for U contamination. Isotopically there is no clear distinction between high and low U groundwater.     

Methane content and isotopic composition of shallow groundwater: implications for environmental monitoring related to shale gas exploitation

The baseline methane for shallow groundwater can provide an important evidence to interpret possible methane stray associated with shale gas exploration. This study investigated and traced methane content and its origin of shallow groundwater in a karst aquifer in the Fuling shale gas block, SW China. The results show that methane contents of shallow groundwater are all less than 0.01 mg L^?1 and volumetric content in dissolved gas ranges from not detected to 0.0064%. The δ¹³C-CH₄ ranges from ?74.4 to ?49.1‰, suggesting biogenic origin. For the first time, the δ¹³C-CH₄ and ³He/⁴He end-numbers were determined.     

Characterizing the groundwater renewability and evolution of the strongly exploited aquifers of the North China Plain by major ions and environmental tracers

The Yongding River Alluvial Fan is a northwestern part of the North China Plain, at which Beijing is located. Since 1950 and especially 1970, excessive groundwater exploitation has resulted in a significant drop of groundwater table, and it’s believed that groundwater will be intensively used continuously in the future. It’s essential to reveal the renewability and the evolution of the groundwater for reasonable management, which was achieved based on the analyses of the major ions and environmental tracers in groundwater. According to the dating results of ³H, CFCs, and ¹⁴C, the age of the shallow and deep groundwater was from <5 to 60 a and from <4,000 to >12,000 a, respectively. The recharge rate determined by the groundwater age generally had a decreasing trend from the NW (0.40–1.44 m/a) to the SE (0.07–0.48 m/a). Na and HCO₃ accumulated from the NW to the SE and the latter was the dominant anion. Chemical modification occurred progressively along the flow paths. The water type of the shallow and deep groundwater changed from Ca–Mg–HCO₃ to Na–HCO₃ and from Ca–Mg–HCO₃ to Ca–Na–Mg–HCO₃ and Na–Ca–Mg–HCO₃ from the NW to the SE, respectively. The shallow groundwater was vulnerable and susceptible to contamination scattered throughout the region, which would probably further extend to the deep groundwater because of the vertical groundwater flow especially through the preferential pathways due to their increasing hydraulic connections.     

Nuclear techniques to investigate source and origin of groundwater pollutants and their flow path at Indian Rare Earths Ltd., Cochin,Kerala

Hydrochemical, environmental isotope and injected radiotracer investigations were carried out in order to investigate the possible source of contaminants and their movement in groundwater at Indian Rare Earths (IRE) site. Water samples were collected from piezometers, dug wells and river in and around IRE site for measurement of physical parameters, chemistry and isotopes. Chemical results show high fluoride, nitrate, sulphate and phosphate concentrations in piezometers whereas dug wells and river samples are free from contamination. Isotope data indicate that the contaminated groundwaters are enriched in δ²H and δ¹⁸O compared to dug well and river samples. Radiotracer experiments were carried out using single-well and multi-well techniques (radiotracers: ⁸²Br and ³H) for determining groundwater filtration velocity and flow direction, respectively. Groundwater filtration velocity was found to be about 1.3 cm/day and flow direction is from south to north. Based on the investigations it can be concluded that groundwater is getting contamination from southern part of IRE campus and the possible source for these contaminants could be the Fertilizer and Chemical of Travancore (FACT) industry.     

Assessment of environmental radioactive elements in groundwater in parts of Nalgonda district,Andhra Pradesh,South India using scintillation detection methods

The objective of this work was to determine the radioactive element concentrations in groundwater in parts of the Nalgonda district. Results indicate that ²²²Rn activity is present in significant levels in deep groundwater compared to shallow groundwater and tank water. An increasing ²²²Rn activity trend is noticed along the well depth while electrical conductivity, uranium, and alkalinity levels showed inverse trends. Environmental tritium data indicates modern recharge to groundwater. Inter-elemental correlations suggest that high dissolved uranium is associated with high alkalinity and high electrical conductivity groundwater. The study also infers recharge sources and mechanisms to shallow and deep groundwater.     

Spatial trends in uranium distribution in groundwaters of Southwest Punjab,India - A hydrochemical perspective

A hydrochemical study was undertaken in uranium impacted districts of southwest Punjab for evaluating the spatial and vertical trends as well as correlations with other hydrochemical parameters. Results infer that U is present in all samples (12.2–621 µg l⁻¹) and 90% are contaminated. Contour diagram depicts contamination in entire region excepting some pockets in central part of the study area. Shallow zones (<50 m bgl) show higher U compared to deeper ones. Hydrochemistry infers a common source of U for both shallow and deep zones and alkalinity as the governing factor for U mobilization from the sediments.

     

Study of uranium isotopic composition in groundwater and deviation from secular equilibrium condition

Uranium concentration in groundwater reflect both redox conditions and uranium content in host rock. In the present study an attempt has been made to study the uranium concentration and activity ratios of uranium isotopes to present the geochemical conditions of the groundwater in Malwa region of Punjab state, India and the reason for high uranium levels and variation of activity ratios from secular equilibrium conditions. Uranium concentration in groundwater samples was found to be in the range of 13.9 ± 1.2 to 172.8 ± 12.3 μg/l with an average value of 72.9 μg/l which is higher than the national and international guideline values. On the basis of uranium concentration, the groundwater of the study region may be classified as oxidized aquifer on normal uranium content strata (20 %) or oxidized aquifer on enhanced uranium content strata (80 %). The ²³⁸U, ²³⁵U and ²³⁴U isotopic concentration in groundwater samples was found to be in the range of 89.2–1534.5, 4.4–68.5, and 76.4–1386.2 mBq/l, respectively. Activity ratios of ²³⁴U/²³⁸U varies from 0.94 to 1.85 with a mean value of 1.11 which is close to unity that shows secular equilibrium condition. High value of ²³⁴U isotope than ²³⁸U may be due to alpha recoil phenomenon. The plot of AR of ²³⁴U/²³⁸U against the total uranium content in log scale reveals that the groundwaters of the study region either belongs to stable accumulation or normal oxidized aquifer.     

Use of 222Rn to trace submarine groundwater discharge in a tidal period along the coast of Xiangshan, Zhejiang, China

²²²Rn is one of the operative tracers for submarine groundwater discharge (SGD), which plays a significant role in the land–ocean interaction of the estuarine and coastal regions. By the distribution pattern of ²²²Rn in atmosphere, groundwater and surface seawater, in a full tidal period (25 h) in March 2012, SGD was estimated along the coast of Xiangshan, Zhejiang, China. ²²²Rn activity in Xiangshan coast was in range of 2.4 × 10⁴–1.7 × 10⁵ Bq/m³ with an average of 9.6 × 10⁴ Bq/m³ for groundwater; 0.2 × 10²–2.8 × 10² Bq/m³ with an average of 1.1 × 10² Bq/m³ for surface seawater. ²²²Rn activities in groundwater were much greater than those in surface water, suggesting that the major source of radon came from coastal groundwater discharge. Rn fluxes of atmospheric emissions, sediment, and of ²²⁶Ra in situ decay can be negligible in this study, but the tidal effects play a crucial role in Rn fluxes. Using a radon inventory equilibrium model, we estimated that the average SGD was 13.2 cm/day and the average terrestrial SGD flux was 1.8 × 10⁸ m³/day. Furthermore, SGD may have a vital impact on the composition and structure of nutrients in seawater, and contribute to eutrophication events occurring in spring season along the coast of the East China Sea.     

Influence of biological activity on <Superscript>65</Superscript>Zn and <Superscript>109</Superscript>Cd removal from tidal water by chronically-polluted mangrove sediments

The biological activity influence on the mangrove sediment capacity to remove ⁶⁵Zn and ¹⁰⁹Cd from tidal water was evaluated in a site chronically polluted. Benthic Activity Indexes (BAI), corresponding to relative estimates of biological impact on radiotracer accumulation, were higher for ¹⁰⁹Cd (~?38%) than for ⁶⁵Zn (~?10%) in the top centimetre of sediment. However, BAI exceeded 96% for deeper sediment layers. This apparent decrease in radiotracer diffusion into deep sediments through biological activity inhibition is stronger than reported for much less polluted mangrove nearby, suggesting that benthic organisms tolerant of chronic metal pollution may affect metal sorption mechanisms.     

Variability of 40K isotopic composition in forest soils under different environmental conditions

Radiopotassium isotopic composition (⁴⁰K/K, %) of several forest soils did not show a constant value of generally known 1.17 × 10^?2 %, but they were varied significantly from 0.4 × 10^?2 to 1.3 × 10^?2 % at different locations under different environmental conditions. Surface portion of a soil (2–4 cm in depth) gave always lower ⁴⁰K/K values compared with those of deeper soil layer (35–40 cm in depth). Ion exchange of K⁺ with NH₄ ⁺ did not affects the ⁴⁰K/K value in any soils, which revealed with chemical leaching experiments in the laboratory. Some plant species showed much lower ⁴⁰K/K values than those in the surface soil. Possible reasons for varying ⁴⁰K/K values obtained in this study may result from a dynamic behavior of potassium in soil, probably due to biological activity including root uptake and decomposing soil organic matter by microorganisms in the forest floor.     

Occurrence of uranium in groundwater of a shallow granitic aquifer and its suitability for domestic use in southern India

Groundwater used for domestic purpose without proper treatment should be free from chemical and biological contaminants. This study was carried out to assess the groundwater quality with respect to uranium in a part of Nalgonda district, Andhra Pradesh, India. Groundwater was regularly monitored for uranium concentration by collection of samples once every two months from March 2008 to November 2009 from 44 wells. The concentration of uranium in groundwater ranged from 0.2 to 118.4 ppb. Groundwater is unsuitable for domestic use in 2 % of this area based on the limit of 60 ppb prescribed by the Atomic Energy Regulatory Board of India. However, due the wide variation in limit suggested by different organizations and countries, the no-observed-adverse-effect level and lowest-observed-adverse-effect level (in mg/kg day) was used to understand the dosage of uranium that reaches the people through drinking water pathway. This level varied from 0 to 0.02 mg/kg day and 0 to 0.08 mg/kg day based on an uncertainty factor of 10 and 50 respectively for the mean uranium concentration in groundwater in each well. With an uncertainty factor of 50, 5 groundwater samples had uranium above 0.06 mg/kg day which is the lowest-observed-adverse-effect level. This study showed that with the presence of present level of uranium concentration in groundwater of this area there is no major threat to humans through the drinking water pathway.     

Activity concentration of uranium in groundwater from uranium mineralized areas and its neighborhood

Uranium mineralization in parts of northeastern Nigeria necessitated its exploration during early eighties by the Nigeria Uranium Mining Company (NUMCO) which was later abandoned. During their course of decay, uranium isotopes pass through radioactive decay stage and eventually into stable isotope of lead. The course of concern for soluble uranium in groundwater especially from the mineralized areas include ionizing radiation, chemical toxicity and reproductive defects for which ingested uranium has been implicated to have caused. This study is aimed at assessing the levels of concentration of uranium in groundwater to ascertain its compliance with the World Health Organization’s (WHO) and the United State Environmental Protection Agency’s (EPA) guideline for uranium in drinking water. Thirty five groundwater samples were collected using EPA’s groundwater sampling protocol and analyzed at the Department of Geology, University of Cape Town using an Inductively Coupled Plasma Mass Spectrometric (ICP-MS) technique. Significant finding of this work was that there is radiological contamination of groundwater in the area. There is also an indication that the extent of radiological contamination is not much within the mineralized zones, therefore, there is likelihood that groundwater has acted as a medium of transporting and enhancing uranium in groundwater in an environment away from that of origin. About 5.7 % of the samples studied had uranium concentration above WHO and EPA’s maximum contaminant level of 30 μg/L which is a major concern for inhabitants of the area. It was also apparent that radiological contamination at the southwestern part of the study area extends into the adjacent sheet (sheet 152). Uranium concentration above set standards in those areas might have originated from rocks around established mineralized zones but was transported to those contaminated areas by groundwater that leaches across the host rock and subsequently mobilizing soluble uranium along with it.     

Radiotracer investigation in a rotary fluidized bioreactor

A rotary fluidized bioreactor (RFBR) designed for treatment of wastewater was required to be investigated for its hydrodynamic behaviour and validation of design. A radiotracer investigation was carried out to measure residence time distribution (RTD) of wastewater in the RFBR using ⁸²Br as a radiotracer. The radiotracer was instantaneously injected into the inlet feed line and monitored at the inlet and outlet of the reactor using collimated scintillation detectors connected to a data acquisition system. The measured RTD data was treated and simulated using a tanks-in-series model and model parameters i.e. number of tanks describing the degree of mixing was obtained. The results of the investigation showed no flow abnormalities and the reactor behaved as an ideal continuously stirred-tank reactor at all the operating conditions. Based on the results, the design of the reactor was validated.     

Integrated Hydrogeological,Hydrochemical, and Isotopic Assessment of Seawater Intrusion into Coastal Aquifers in Al-Qatif Area,Eastern Saudi Arabia

Seawater intrusion (SWI) is the main threat to fresh groundwater (GW) resources in coastal regions worldwide. Early identification and delineation of such threats can help decision-makers plan for suitable management measures to protect water resources for coastal communities. This study assesses seawater intrusion (SWI) and GW salinization of the shallow and deep coastal aquifers in the Al-Qatif area, in the eastern region of Saudi Arabia. Field hydrogeological and hydrochemical investigations coupled with laboratory-based hydrochemical and isotopic analyses (¹⁸O and ²H) were used in this integrated study. Hydrochemical facies diagrams, ionic ratio diagrams, and spatial distribution maps of GW physical and chemical parameters (EC, TDS, Cl⁻, Br⁻), and seawater fraction (f_sw) were generated to depict the lateral extent of SWI. Hydrochemical facies diagrams were mainly used for GW salinization source identification. The results show that the shallow GW is of brackish and saline types with EC, TDS, Cl⁻, Br⁻ concentration, and an increasing f_sw trend seaward, indicating more influence of SWI on shallow GW wells located close to the shoreline. On the contrary, deep GW shows low f_sw and EC, TDS, Cl⁻, and Br⁻, indicating less influence of SWI on GW chemistry. Moreover, the shallow GW is enriched in ¹⁸O and ²H isotopes compared with the deep GW, which reveals mixing with recent water. In conclusion, the reduction in GW abstraction in the central part of the study area raised the average GW level by three meters. Therefore, to protect the deep GW from SWI and salinity pollution, it is recommended to implement such management practices in the entire region. In addition, continuous monitoring of deep GW is recommended to provide decision-makers with sufficient data to plan for the protection of coastal freshwater resources.     

Use of isotope hydrology for groundwater resources study in Upper Chi river basin

The Upper Chi river basin is located in the vicinity of Chaiyaphum province, northeastern Thailand. Groundwater management in the drought affected area of fractured Mesozoic siliciclastic rocks groundwater system was challenged by the approaches of isotope and chemical techniques. The local meteoric water line (LMWL) of the study area provide lower slope (δD = 6.8508δ¹⁸O ? 0.8013) and more depleted average annual rainfall (δ¹⁸O = ?7.6 %ο) when compare to LMWL of Bangkok due to higher evaporation. The surface water mainly exhibits an evaporation effect and can be clearly divided into two groups, the upper reaches and the downstream areas, with approximate separated in δ¹⁸O by ?4.0 %ο. The groundwater system in the area can be divided into seven subareas based on the stable isotope characteristics and groundwater dating by radiocarbon and tritium methods. Nong Bua Deang subarea, Kang Kro subarea, and Thep Satit subarea, the most upstream system which were separated by thick aquitards of Phra Wihan sandstones, are classified as the upper reach area. The groundwater samples are characterized in two traits: the upstream group shows older groundwater ages (<80.0 % modern carbon, PMC) because of less interaction with surface water and the downstream group, near main channels and reservoirs, exhibit younger groundwater ages because of contribution of surface water in the recharge area. Bamnet Narong subarea and Muang Chaiyaphum subarea are classified as the middle reach area. The groundwater shows rapidly recharge from rainfall, the results of radiocarbon provide younger ages. The downstream characteristic which is closely interaction of extremely evaporated surface, were found in Kon Sawan-Mancha Kiri subarea and Ban Phai subarea. Almost all the groundwater samples are related to younger ages except the wells near the upper tributaries. The groundwater management can be proposed by attending to conservation policy in the upper reach area, and some parts of Ban Phai subarea in which groundwater is slowly replenished slowly, as well as groundwater exploration will be expanded in the Bamnet Narong subarea and the Muang Chaiyaphum subarea which is the most effective zones for groundwater developments.     

Study of the gamma spectrum of 16N with a BGO detector, for the purpose of calibration and of determining the fluorine grade of mineral samples

Over the past several years, the Pacific Northwest National Laboratory (PNNL) has developed an ultra-low-background proportional counter (ULBPC) technology. The resulting detector is the product of an effort to produce a low-background, physically robust gas proportional counter for applications like radon emanation measurements, groundwater tritium, and ³⁷Ar. In order to fully take advantage of the inherent low-background properties designed into the ULBPC, a comparably low-background dedicated counting system is required. An ultra-low-background counting system (ULBCS) was recently built in the new shallow underground laboratory at PNNL. With a design depth of 30 m water-equivalent, the shallow underground laboratory provides approximately 100× fewer fast neutrons and 6× fewer muons than a surface location. The ULBCS itself provides additional shielding in the form of active anti-cosmic veto (via 2-in-thick plastic scintillator paddles) and passive borated poly (1 in.), lead (6 in.), and copper (~3 in.) shielding. This work will provide details on PNNL’s new shallow underground laboratory, examine the motivation for the design of the counting system, and provide results from the characterization of the ULBCS, including initial detector background.     

Uranium, radium and tritium groundwater monitoring at INFN-Gran Sasso National Laboratory, Italy

Uranium groundwater anomalies, which were observed in cataclastic rocks crossing the underground Gran Sasso National Laboratory before the L’Aquila earthquake (April 6th, 2009), have been studied versus radium and tritium contents. The radionuclide analysis supports the role of endogenic fluid dynamics for uranium content in groundwater rather than percolation processes, due to meteoric events occurring above the water table of the Gran Sasso aquifer. The uranium anomalies represent a key geochemical signal of a progressive increase of deep fluids fluxes at middle-lower crustal levels associated with the geodynamics of the earthquake. Moreover, the uranium represents a more precise strain-meter than radon as its presence can be modulated during the preparation phase of the earthquake, and only successively released by microfracturing during the main shock and aftershocks.     

Counting Radio-Krypton Atoms with a Laser

Because of their unique chemical and physical properties, long-lived rare krypton radioisotopes, ⁸⁵Kr and ⁸¹Kr, are ideal tracers for environmental samples, including air, groundwater and ice. Atom trap trace analysis (ATTA) is a new laser-based method for counting both ⁸⁵Kr and ⁸¹Kr atoms with the abundance as low as 10^-14 with micro-liters (STP) krypton gas. The entire system for rare radio-krypton measurement built at Hefei is presented, including the atom trap trace analysis instrument and sampling apparatus of gas extraction from water and krypton purification. Atmospheric⁸⁵Kr concentrations at different places in China were measured, showing a range of 1.3-1.6 Bq/m³, consistent with the northern hemispheric baseline. As a demonstration of the system, some shallow and deep groundwater samples in north and south China were sampled and dated.     

Discrimination of zone-specific spectral signatures in normal human prostate using Raman spectroscopy

The prostate gland is the most common site of pathology in human males. Using the urethra as an anatomical reference point, it can be divided into three distinct zones known as the transition zone (TZ), peripheral zone (PZ) and central zone (CZ). The pathological conditions of benign prostatic hypertrophy and/or prostate adenocarcinoma are highly prevalent in this gland. This preliminary study set out to determine whether biochemical intra-individual differences between normal prostate zones could be identified using Raman spectroscopy with subsequent exploratory analyses. A normal (benign) prostate transverse tissue section perpendicular to the rectal surface and above the verumontanum was obtained in a paraffin-embedded block. A 10-μm-thick slice was floated onto a gold substrate, de-waxed and analysed using Raman spectroscopy (200 epithelial-cell and 140 stromal spectra/zone). Raman spectra were subsequently processed in the 1800-367 cm(-1) spectral region employing principal component analysis (PCA) to determine whether wavenumber-intensity relationships expressed as single points in hyperspace might reveal biochemical differences associated with inter-zone pathological susceptibility. Visualisation of PCA scores plots and their corresponding loadings plots highlighted 781 cm(-1) (cytosine/uracil) and 787 cm(-1) (DNA) as the key discriminating factors segregating PZ from less susceptible TZ and CZ epithelia (P < 0.001). Conversely, 1459 cm(-1) (lipids and proteins) and 1003 cm(-1) (phenylalanine) were identified as the key biochemical factor distinguishing TZ from CZ epithelia (P < 0.05). All stromal zones were discriminated by the protein/lipid region (1459 cm(-1) and 1100 cm(-1)) with DNA/RNA region (781 cm(-1) and 787 cm(-1)) only highlighted between PZ and CZ (P < 0.05). This novel approach identifies biochemical markers that may have aetiological functional roles towards susceptibility of human prostate zones to specific pathological conditions.     

Electrochemical measurement and speciation of inorganic arsenic in groundwater of Bangladesh

The presence of arsenic in groundwater above the maximum permissible limit of 50 mug l(-1) has threatened the health of more than 50 million people in Bangladesh and neighboring India. We report here the development of an inexpensive anodic stripping voltammetric (ASV) technique for routine measurement and speciation of arsenic in groundwater. The measurements are validated by more expensive atomic absorption, atomic emission and other techniques. To understand the present situation in Bangladesh, we measured As(III) in 960 water samples collected from 18 districts. A random distribution of 238 samples was used to measure both As(III) and As(V). The results from the present study indicate that most toxic form of inorganic arsenic, As(III), has the broad range of 30-98%. It shows 60% of the samples have 10 mug l(-1) and 44% of the samples have 50 mug l(-1) or more As(III). The fractional distribution pattern shows significant skew towards high percent occurrence which may indicate a progressive reduction process with a single source or a single mechanism for the formation of As(III). For direct consumption, this is possibly one of the most toxic groundwater known today. Speciation distribution at groundwater pH value shows H(3)AsO(3) is the predominant species including H(2)AsO(4)(-) and H(2)AsO(4)(2-) whose distribution is significantly pH dependent. This is also supported by E(h)-pH measurements. The depth distribution for Kushtia shows most of the As(III) is located within 100-200 ft deep aquifers. Similar fractional distribution of As(III) is found in deeper aquifers and may indicate contamination by leakage from upper aquifer. This study clearly demonstrates the aquifer environment is reductive and conducive to the formation of As(III) species.