Activity ratios of 234 U/ 238 U and 226 Ra/ 228 Ra for transport mechanisms of elevated uranium in alluvial aquifers of groundwater in south-western (SW) Punjab, India

Kumar, Ajay; Karpe, Rupali; Rout, Sabyasachi; Gautam, Y. P.; Mishra, Manish; Ravi, P.M.; Tripathi, R. M.

doi:10.1016/j.jenvrad.2015.10.020

Cited by 26 publications

(6 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Analysis of compiled groundwater quality data points to critical uranium (U) contamination (≫30 μg L –1 WHO drinking water guideline) concentrated within the northwestern parts of the Indo-Gangetic Plain (IGP), specifically in certain regions of the states of Punjab, Haryana, and Rajasthan (Figure ). Very high U concentrations (>600 μg L –1 ) in groundwater were localized within the southern districts of Punjab. ,− Concentrations seemed to decrease from an average of ∼83 μg L –1 ,, in this zone to less than half in other parts of the state. ,− In the districts of Rajasthan and Haryana bordering southwest Punjab, elevated average U concentrations of ∼54 and 36.9 μg L –1 , respectively, were reported. − Concentrations decreased toward the southeastern districts of Rajasthan to about 42 μg L –1 . ,,, However, isolated locations further south were reported to have high U concentrations of ∼319 μg L –1 . A detailed compilation of the relevant U concentrations can be found in the “U dataset” and “District-wise U distribution” worksheets of the Electronic Annexure.…”

Section: Resultsmentioning

confidence: 96%

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Sujathan

Singh

2023

Environ. Sci. Technol.

View full text Add to dashboard Cite

Elevated uranium (U) (>WHO limit of 30 μg L −1 ) in Indian groundwaters is primarily considered geogenic, but the specific mineralogical sources and mechanisms for U mobilization are poorly understood. In this contribution, statistical and geochemical analyses of well-constrained metadata of Indian groundwater quality (n = 342 of 8543) were performed to identify key parameters and processes that influence U concentrations. For geochemical predictions, a unified speciation model was developed from a carefully compiled and updated thermodynamic database of inorganic, organic (Stockholm Humic model), and surface complexation reactions and associated constants. Critical U contamination was found at shallow depths (<100 m) within the Indo-Gangetic plain, as determined by bivariate nonparametric Kendall's Tau b and probability-based association tests. Analysis of aquifer redox states, multivariate hierarchical clusters, and principal components indicated that U contamination was predominant not just in oxic but mixed (oxic−anoxic) aquifers under high Fe, Mn, and SO 4 concentrations, presumably due to U release from dissolution of Fe/Mn oxides or Fe sulfides and silicate weathering. Most groundwaters were undersaturated with respect to relevant U-bearing solids despite being supersaturated with respect to atmospheric CO 2 (average pCO 2 of reported dissolved inorganic carbonate (DIC) data = 10 −1.57 atm). Yet, dissolved U did not appear to be mass limited, as predicted solubilities from reported sediment concentrations of U were ∼3 orders of magnitude higher. Integration of surface complexation models of U on typical aquifer adsorbents, ferrihydrite, goethite, and manganese dioxide, was necessary to explain dissolved U concentrations. Uranium contamination probabilities with increasing dissolved Ca and Mn exhibited minima at equilibrium solubilities of calcite [∼50 mg L −1 ] and rhodochrosite [∼0.14 mg L −1 ], respectively, at an average groundwater pH of ∼7.5. A potential indirect control of such U-free carbonate solids on U mobilization was suggested. For locations (n = 37) where dissolved organic carbon was also reported, organic complexes of U contributed negligibly to dominant U speciation at the groundwater pH. Overall, the unified model suggested competitive dissolution−precipitation and adsorption−desorption controls on U speciation. The model provides a quantitative framework that can be extended to understand dominant mobilization mechanisms of geogenic U in aquifers worldwide after suitable modifications to the relevant aquifer parameters.

show abstract

Section: Resultsmentioning

confidence: 96%

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Sujathan

Singh

2023

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…Otherwise, when a parent radionuclide decays directly to another isotope of the same element (as in case of the uranium isotopes 238 U and 234 U) usually in any kind of abiotic materials the isotopes remain in secular equilibrium. In nature, processes resulting in isotopic fractionation of an element are very rare and the consequences, if exists, are negligible from the radiation protection perspective, especially in the context of building materials [Koide and Goldberg, 1963;Grabowski and Bem, 2011;Kumar et al, 2016]. In contrast, human activity can significantly change isotope ratios (for example, enrichment or depletion of uranium in the nuclear fuel cycle).…”

Section: Disequilibrium In Natural Decay Seriesmentioning

confidence: 99%

Measurement of radioactivity in building materials – Problems encountered caused by possible disequilibrium in natural decay series

Michalik

Schroeyers

2018

Construction and Building Materials

View full text Add to dashboard Cite

The determination of the activity concentration of naturally occurring radionuclides in construction materials is based on the principles of gamma-spectrometry. Gamma spectrometry is a comparative method and therefore includes many parameters that are specific to the test sample and measurement circumstances. Consequently, several of the testing conditions must be verified prior to testing and/or require correction to obtain accurate results. Besides problems encountered during the measurement, the interpretation of the results and calculation of the activity indices, needed for material classification, may lead to significant mistakes. Current regulation in the European Union requires to calculate an activity concentration index (index I) using the activity concentration of 226 Ra, 232 Th and 40 K. Not all of these radionuclides are directly measurable by gamma spectrometry and, to determine the index, additional assumptions have to be made about secular equilibrium in uranium and thorium decay series. These assumptions are often not valid in case of NORM (Naturally Occurring Radioactive Materials) where long term lack of secular equilibrium in the uranium and/or thorium decay series is often observed. As a consequence, this may result in an underestimation or overestimation of the index. The article discusses specific disequilibrium situations in building materials. Sources for potential inaccurate determinations and misinterpretation are identified and practical mitigation options are proposed.

show abstract

“…Most of the uranium minerals reported in Peña Blanca form uranyl ion compounds. The activity ratio (AR) is used as a geochemical tool to investigate the transport and flow relationships of uranium isotopes in waters [7]. If the activity concentrations Act (AU) of the corresponding isotopes are known, the activity ratio (AR) is defined as:…”

Section: Introductionmentioning

confidence: 99%

Transport and concentration of uranium isotopes in the Laguna del Cuervo, Chihuahua, Mexico

Pérez-Reyes

Cabral-Lares

Méndez-García³

et al. 2022

Supl. Rev. Mex. Fis.

View full text Add to dashboard Cite

In Chihuahua, an important source of environmental radioactivity is found in the Sierra Peña Blanca, in the center of the state. The site comprises about 70% of uranium reserves in Mexico. The uranium of Peña Blanca was explored and partially exploited in the '80s. Due to the closure of operations, the extracted and unprocessed ore (hundreds of tons) was confined to rocky stacks, exposed to weathering. Subject to leaching, this uranium is transported from the mountains to Laguna del Cuervo. The mineral exposed in the repository and the uranium transport by surface water and recent sediments must be studied, to assess the effects on the environment, with radiometric and materials science techniques in conventional laboratories and synchrotron light. This work presents the study of sediment and pore water samples at various points along the lagoon, and the values of the activity ratio of the 234U/238U isotopes and the sediment-water distribution coefficient of these isotopes, obtained by applying uranium liquid scintillation alpha spectrometry, gamma-ray spectrometry, scanning electron microscopy and X-ray diffraction methods.

show abstract

Activity ratios of 234 U/ 238 U and 226 Ra/ 228 Ra for transport mechanisms of elevated uranium in alluvial aquifers of groundwater in south-western (SW) Punjab, India

Cited by 26 publications

References 58 publications

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Investigation of Potential Drivers of Elevated Uranium Prevalence in Indian Groundwaters with a Unified Speciation Model

Measurement of radioactivity in building materials – Problems encountered caused by possible disequilibrium in natural decay series

Transport and concentration of uranium isotopes in the Laguna del Cuervo, Chihuahua, Mexico

Contact Info

Product

Resources

About