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.     

Comparison of radiometric and non-radiometric methods for uranium determination in groundwater of Punjab,India

Uranium in groundwater samples collected from Punjab state, India was determined using radiometric methods (extractive liquid scintillation and Cerenkov counting). Experimental conditions were optimized by studying the effect of sample pH, quenching and amount of extracting agent added to the scintillation cocktail on recovery of uranium. To ensure the accuracy of results, both radiometric methods were compared with non radiometric method such as adsorptive stripping voltammetry and found to be very good agreement. The distinct advantage of proposed radiometric methods is almost 100 % effective especially extractive liquid scintillation for simultaneous measurement of alpha and beta emitting radionuclides with fast and simple sample preparation.     

Spatial dependency of the groundwater uranium in the alluvial soil region of Gunnaur,India

Journal of Radioanalytical and Nuclear Chemistry - GIS based groundwater uranium and other physico-chemical parameters pH, electrical conductivity, oxidation reduction potential, temperature,...     

Radiation-induced OH radical generation and its use for groundwater remediation

Because of nitrite hydrogenperoxide formation irradiation treatment alone is not apt for groundwater remediation with regard to utilization as drinking water. Addition of ozone to the water before irradiation eliminates the nitrite and hydrogen peroxide as well and causes the reducing species of water radiolysis to be converted into OH radicals. The resulting advanced oxidation process is the only one which is based on two OH radical sources: water radiolysis and ozone decomposition. The basic chemistry and a 3 m³ prototype installation is described.     

Assessment of chemo-radiological risk of naturally occurred uranium in groundwater from the Beed district,India

The main objective of study is assessment of chemo-radiological risk using measured concentrations of uranium in drinking water. For estimation of U concentration, LED Fluorimeter was used. For data accuracy, statistical tools were applied, geographical distribution GIS based software were used. To assess relation between uranium to other parameters, correlation test was performed. On the basis of presence of U in the water, hazard quotient, effective dose and cumulative dose for lifetime were estimated, it ranges from 0.001 to 1.09, 0.01–18.61 μSv year⁻¹ and 1.22–1303 μSv for lifetime correspondingly. The estimated ingested dose is well below than the suggested limit of 0.1 mSv.

     

Occurrence of the radionuclides in groundwater of crystalline hard rock regions of central Tamil Nadu,India

A study was conducted to understand the occurrence of the radionuclides in groundwater of crystalline hard rock region. Samples were collected to analyze major cations, anions, U, ²²²Rn and stable isotopes of oxygen, hydrogen. It was inferred that few samples have U and ²²²Rn concentrations higher than the permissible limit of drinking water standard. High degree of weathering of granitic rocks and long contact time of groundwater with the aquifer matrix could be the reason for enhanced U and ²²²Rn levels in groundwater. The association of U with SO₄ also proves that there exists anthropogenic influence in groundwater composition.     

Health risks associated with the exposure to uranium and heavy metals through potable groundwater in Uttarakhand state of India

The present work aims to assess health risks associated with the exposure to uranium and heavy metals via potable groundwater in Uttarakhand state of India. For this purpose, potable groundwater samples were collected from the area and analyzed using LED fluorimetry and inductively coupled plasma mass spectrometry (ICPMS). The radiological (carcinogenic) and chemical (non-carcinogenic) risks associated with the exposure to uranium in majority of locations were observed below the safe limits suggested by WHO and USEPA. The levels of heavy metals present in potable groundwater were found well below the permissible limits recommended by WHO. An inter-comparison exercise between the results obtained with LED fluorimetry and ICPMS techniques was performed for the assurance of reliability and accuracy of results. The results were found in good agreement with each other.

     

Behavior of uranium under various redox conditions in a shallow brackish lake

The behavior of uranium under various redox conditions was investigated in the brackish Obuchi lake surrounded by an uranium enrichment plant and facilities currently under construction for reprocessing of spent nuclear fuel in Rokkasho Village in northern Japan. Our investigation showed that uranium in water under oxic conditions can be explained by the simple mixing of freshwater and seawater, and the source of uranium in the lake is mainly seawater. The ratios of ²³⁸U/salinity under oxic conditions were approximately 0.09-0.12 g^.l^-1.psu^-1. However, the ratios of ²³⁸U/salinity in bottom layer water under anoxic condition in summer were lower (0.07-0.09 g^.l^-1.psu^-1) than those in seawater. ²³⁸U concentrations in pore water sampled under anoxic conditions were very low (0.05-0.06 g^.l^-1.psu^-1). Moreover, the relationships between the ²³⁸U/Al ratios and the Fe/Al ratios of particle substances were strongly correlated. This suggests that uranium in the bottom-layer water may be precipitated to an insoluble form in the anoxic state, and Fe is the major carrier of insoluble uranium.     

Quantification of radon concentration in groundwater around abandoned Gogi uranium mineralized zone,Yadagir district,Karnataka, India

Journal of Radioanalytical and Nuclear Chemistry - Radon activity concentrations have been measured by analysing a total of 93 bore well water samples, geographically spread over three taluks of...     

Biological effects of uranium in water,soil and rice in uranium deposits in southern China

Journal of Radioanalytical and Nuclear Chemistry - The content of radionuclide uranium in the water, soil and rice around the decommissioned uranium mine was analyzed, and the radioactive...     

Assessment of natural uranium and 226Ra concentration in ground water around the uranium mine at Narwapahar, Jharkhand, India and its radiological significance

A brief study on dissolved radionuclides in aquatic environment, especially in ground water, constitutes the key aspect for assessment and control of natural exposure. In the present study the distribution of natural uranium and ²²⁶Ra concentration were measured in ground water samples collected within a 10 km radius around the Narwapahar uranium mine in the Singhbhum thrust belt of Jharkhand, India in 2007–2008. The natural uranium content in the ground water samples in this region was found to vary from 0.1 to 3.75 μg L^?1 with an average of 0.87 ± 0.73 μg L^?1 and ²²⁶Ra concentration was found to vary from 5.2 to 38.1 mBq L^?1 with an average of 13.73 ± 7.34 mBq L^?1. The mean annual ingestion dose due to intake of natural uranium and ²²⁶Ra through drinking water pathway to male and female adults population was estimated to be 6.55 and 4.78 μSv y^?1, respectively, which constitutes merely a small fraction of the reference dose level of 100 μSv y^?1 as recommended by WHO.     

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.     

Disequilibrium of uranium series radionuclides in soil and plants of South India

Soil and plants of South India were analysed using standard methods for equilibrium state between radionuclides ²²⁶Ra, ²¹⁰Pb, and ²¹⁰Po of uranium series. A disequilibrium state was observed, with mean ²¹⁰Pb/²²⁶Ra, ²¹⁰Po/²²⁶Ra, and ²¹⁰Po/²¹⁰Pb as 21.71, 5.52, and 0.40; 10.01, 4.21, and 0.43; and 30.86, 9.34, and 0.35 in Coastal Karnataka, Malnad Karnataka, and Malnad Kerala, respectively. ²¹⁰Po/²¹⁰Pb in soil was 0.29, 0.30, and 0.49 respectively, for the three regions. Unsupported ²¹⁰Pb and ²¹⁰Po might have caused the observed disequilibrium state. The investigation helps to monitor radionuclide distribution and dynamics in soil and plants of the study area.

     

An automatic gravimetric titrator and its use for the potentiometric determination of uranium by the Davies and Gray method

Summary Construction and mode of operation of an automatic gravimetric titrator are described. Center of the system is a Titroprint E 475 which was modified on a few points. The titrant is added by use of two automatically controllable motor burettes as a main volume, and then in steps of 0.01 ml. The losses of weight of the reservoir vessel are correspondingly recorded by an electronic balance. The measured data are obtained on a punched tape and allow evaluations of the analysis as gravimetric and volumetric titration by use of two Basic computer programs. When the system was used for the potentiometric determination of uranium a relative standard deviation of 0.48 (gravimetric and volumetric) and relative deviations from the nominal value of –0.41 (gravimetric) and –0.79 (volumetric) were obtained as mean values for 14 groups of 5–6 samples.

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Ein automatischer gravimetrischer Titrator und seine Anwendung für die potentiometrische Bestimmung von Uran nach Davies und Gray

Zusammenfassung Es werden Aufbau und Betriebsweise eines automatischen gravimetrischen Titrators beschrieben, dessen Hauptkomponente ein in mehreren Punkten modifizierter Titroprint E 475 ist. Das Titrationsmittel wird mit zwei elektronisch steuerbaren Motorbüretten grob- bzw. feindosiert, wobei eine elektronische Waage die entsprechenden Gewichtsverluste des Reservoirgefäßes registriert. Die auf Lochstreifen ausgegebenen Meßdaten lassen Auswertungen der Analyse als gravimetrische und volumetrische Titration über entsprechende Basic-Computerprogramme zu. Bei Benutzung des Systems für die potentiometrische Bestimmung von Uran wurden für Gruppen von 5–6 Proben mittlere relative Standardabweichungen von 0,48 (gravimetrisch und volumetrisch) sowie mittlere relative Abweichungen vom Sollwert von –0,41 (gravimetrisch) bzw. –0,79 (volumetrisch) erhalten.

     

Occurrence characteristics and influencing factors of uranium and radon in deep-buried thermal storage aquifers

Journal of Radioanalytical and Nuclear Chemistry - To clarify the enrichment characteristics of uranium and radon in deep-buried geothermal water, 39 geothermal water samples with a buried depth of...