Uranium Contamination In Groundwater Research Articles

The impact of uranium contamination in groundwater on human health: a toxicological risk assessment

ABSTRACT All living beings are exposed to naturally occurring radionuclides. Uranium, a primordial radionuclide forms compounds that are water soluble and enter the human body through food and drinking water. This study conducted a health risk assessment to evaluate the potential dangers associated with consuming uranium through groundwater in the Mansa district of Punjab, India. The uranium concentration varied from 43.43 µg/L to 449.79 µg/L. The biokinetic model of uranium including hair compartment as excretion pathway is used to calculate uranium retention in different organs of the human body. The Pearson correlation and principal component analysis are used for assessing the correlation of uranium with TDS, salinity, conductivity and pH. The high correlation is observed between TDS and uranium. The hazard quotient is 17.42 and excess cancer risk is higher than the permissible limit of 10−4. Owing to the high uranium concentration in Mansa district, periodic monitoring is advised along with clinical investigation of the population.

Toxic uranium contamination in groundwater of Thoothukudi district, India: Evaluation of health risks using the geochemical and statistical approach

The present investigation aims to determine the health risks of toxic uranium contamination in the drinking water of the Thoothukudi district. Two hundred and eighty-six samples were examined during the pre- and post-monsoon seasons and found the uranium concentration ranges from <0.2 to 167 ppb (mean 12, Standard deviation 21) (pre-monsoon) and <02 to 190 ppb (mean 13, Standard deviation 24) (post-monsoon). Geochemical modeling studies and the reducing nature of samples reveal that the uraninite mineral is under saturated conditions, and the least soluble U4O9 mineral species is predominantly distributed during both seasons. Statistical analysis provides that applying nitrogen and phosphate fertilizers may induce the dissolution of uranium minerals, which is responsible for elevated uranium in the collected samples. The calculated noncarcinogenic risk of uranium range from 0.005 to 8.09 (pre-monsoon) and 0.005 to 9.18 (post-monsoon). 15% (pre-monsoon) and 17% (post-monsoon) of the samples show a higher noncarcinogenic risk. The calculated cancer mortality and morbidity are within the permissible limit of 10−3, and the present health risk assessment of uranium is evident that the people from this district have the chemical toxicity of uranium than the carcinogenic risk due to drinking water.

Application of GIS technique to address the uranium contamination in groundwater of a hard rock aquifer, South India

The present research aims to determine the sources and concentration of uranium in the groundwater of the hard rock aquifer. Two hundred and fifty-four groundwater samples were collected, and the analysis shows the uranium concentrations range from 0.5 to 113 ppb (pre-monsoon) and 0.5 to 120 ppb (post-monsoon). Factor analysis illustrates that the lower concentrations of uranium in the study region may be due to the poor dissolution of minerals in the subsurface. Saturation Index values confirm that the Uraninite mineral is undersaturated, and the U4O9 has dominant distribution during both seasons. During both seasons, four samples have a uranium concentration of more than 60 ppb, which might be due to the fertilizer usage in the agricultural activities in the study area. The GIS technique highlights the uranium-contaminated location and polluted water quality parameters using the Inverse Distance Weighted spatial interpolation plots.

Meta-analysis of uranium contamination in groundwater of the alluvial plains of Punjab, northwest India: Status, health risk, and hydrogeochemical processes

Despite numerous studies, there are many knowledge gaps in our understanding of uranium (U) contamination in the alluvial aquifers of Punjab, India. In this study, a large hydrogeochemical dataset was compiled to better understand the major factors controlling the mobility and enrichment of uranium (U) in this groundwater system. The results showed that shallow groundwaters (<60 m) are more contaminated with U than from deeper depths (>60 m). This effect was predominant in the Southwest districts of the Malwa, facing significant risk due to chemical toxicity of U. Groundwaters are mostly oxidizing and alkaline (median pH: 7.25 to 7.33) in nature. Spearman correlation analysis showed that U concentrations are more closely related to total dissolved solids (TDS), salinity, Na, K, HCO3−, NO3− Cl−, and F− in shallow water than deep water, but TDS and salinity remained highly correlated (U-TDS: ρ = 0.5 to 0.6; U-salinity: ρ = 0.5). This correlation suggests that the salt effect due to high competition between ions is the principal cause of U mobilization. This effect is evident when the U level increased with increasing mixed water species (Na-Cl, Mg-Cl, and Na-HCO3). Speciation data showed that the most dominant U species are Ca2UO2(CO3)2− and CaUO2(CO3)3−, which are responsible for the U mobility. Based on the field parameters, TDS along with pH and oxidation-reduction potential (ORP) were better fitted to U concentration above the WHO guideline value (30 μg.L−1), thus this combination could be used as a quick indicator of U contamination. The strong positive correlation of U with F− (ρ = 0.5) in shallow waters indicates that their primary source is geogenic, while anthropogenic factors such as canal irrigation, groundwater table decline, and use of agrochemicals (mainly nitrate fertilizers) as well as climate-related factors i.e., high evaporation under arid/semi-arid climatic conditions, which result in higher redox and TDS/salinity levels, may greatly affect enrichment of U. The geochemical rationale of this study will provide Science-based-policy implications for U health risk assessment in this region and further extrapolate these findings to other arid/semi-arid areas worldwide.

Film-like chitin/polyethylenimine biosorbent for highly efficient removal of uranyl-carbonate compounds from water

Uranium contamination in groundwater has been increasingly reported, while biosorbents for the decontamination attracts growing attention because of their distinct advantages of abundant raw materials and eco-friendliness. Herein, a film-like chitin/polyethylenimine biosorbent (CH-PEI) was prepared and employed in the removal of uranyl-carbonate compounds from water. Fourier transform infrared spectra, element analysis, scanning electron microscopy/energy dispersive X-ray spectroscopy, N2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy were used to characterize the biosorbent. Besides, thermodynamic calculation and various batch experiments were conducted to investigate the adsorption performances of CH-PEI for uranyl removal from carbonate solution. The results showed that the biosorbent possessed a unique hierarchically porous structure and a high nitrogen content. The batch experiments exhibited that it obtained the maximum adsorption capacity at pH = 6. Notably, CH-PEI could reach sorption equilibrium within 4 h at the initial concentration of 50 mg/L. The maximum adsorption capacity were 247.04 mg/g and 1023.74 mg/g at the initial concentrations of 50 mg/L and 300 mg/L. The kinetics and isotherm data were well fitted by pseudo-second-order and Langmuir models. It could remove 98.9% of uranium in the simulated groundwater. The biosorbent showed fast regeneration, good structural stability and reusability in 5 cycles. Furthermore, the adsorption mechanism was confirmed to be anion exchange and electrostatic attraction between nitrogen species and uranyl-carbonate complexes through FT-IR and XPS analysis. Considering its low costs, high efficiency and easy collection, CH-PEI would be a promising biosorbent for uranium removal from groundwater. This study provides a potential technique for uranium removal using chitin-based adsorbents.

Uranium in ground water of Rajnandgaon District of Central India

The present study highlights uranium levels, associated health effects, and physicochemical properties of ground water samples collected from Rajnandgaon District of Chhattisgarh State, Central India. Uranium concentrations of ground water samples are found to exceed than 30 µg/L (United States Environmental Protection Agency and World Health Organisation recommended limit) at two villages in summer and at one village in winter while it is found higher than 60 µg/L (Atomic Energy Regulatory Board, Department of Atomic Energy, India recommended limit) at only one village in summer. Correlation analysis between uranium and physicochemical parameters suggest that Ca2+ ion and total alkalinity play an important role in uranium contamination of ground water.

Characterizing organic carbon dynamics during biostimulation of a uranium contaminated field site

Uranium contamination of groundwater remains a pressing problem at many former uranium mining and milling operations, such as the Rifle, Integrated Field Research Challenge (IFRC) site. Biostimulation of the subsurface with an organic carbon source such as acetate, followed by the microbially-induced reductive precipitation of uranium has been proposed as an effective remediation strategy. While uranium bioreduction has been studied in several field experiments, the transformation and fate of injected carbon remains poorly understood. This study evaluated the impact of added organic carbon on the long-term biogeochemical attenuation of uranium in the subsurface of a former mill tailings site. Fluorescence and ultraviolet–visible absorbance analyses were used together with dissolved organic carbon (DOC) measurements to track organic carbon dynamics during and post-biostimulation of the 2011 Rifle IFRC experiment. An electron mass balance was performed on well CD01 to account for any unidentified carbon sinks. Measured DOC values increased to 1.76 mM-C during biostimulation, and to 3.18 mM-C post-biostimulation over background DOC values of 0.3–0.4 mM-C. Elevated DOC levels persisted for 90 days after acetate injections ceased. The electron mass balance revealed that assumed electron acceptors would not account for the total amount of acetate consumed. Excitation–emission matrices showed an increase in signals associated with soluble microbial products, during biostimulation, which disappeared post-biostimulation despite an increase in total DOC. Specific ultraviolet absorbance analyses, indicated that DOC present post-biostimulation is less aromatic in nature, compared to background DOC. Our results suggest that microbes convert injected acetate into a form of solid phase organic matter that may be available to sustain iron reduction post-stimulation.

Contribution of flyash from coal-fired thermal power plants to uranium contamination of ground water

The elemental concentration of uranium in flyash and coal samples has been investigated using EDXRF and WDXRF techniques. To check the contribution of flyash to uranium contamination of ground water in the Malwa region of Punjab, the flyash and coal samples are collected from Guru Nanak Dev Thermal Power Plant (GNDTPP) in the Bathinda district of Punjab state, India. It is found that uranium concentration in the flyash is below the detection limit of the XRF set up, i.e. ~ 1 ppm. It is concluded that uranium contamination in the ground water of Malwa region is not due to the Thermal Power Plant.

Study on uranium contamination in groundwater of Faridkot and Muktsar districts of Punjab using stable isotopes of water

Environmental isotopic study has been conducted in Faridkot and Muktsar districts of Punjab to assess the uranium contamination as well as to determine the isotopic signatures of contaminated groundwater. Results indicate that U levels range from 3 to 190 µg/L and ten samples are contaminated out of twenty collected. Uranium contamination is observed both in shallow and deep groundwaters but decreases with depth. Positive correlation was found between alkalinity and U. The δ18O values range between −9 and −6‰ and do not show any distinction between contaminated and uncontaminated groundwater.

Potential human health impact of groundwater in non-exploited uranium ores: The case of Horta da Vilariça (NE Portugal)

The anomalous concentration of chemical elements in rocks can have consequences on the human health population even in the absence of anthropogenic activities. Uranium contamination of groundwater is being increasingly recognized as a health threat to rural residents relying on home wells for their drinking water, not only in communities with a legacy of mining, but also where there's naturally occurring uranium. In the Horta da Vilariça region (Torre de Moncorvo, Northern Portugal), a few uranium (U) ores were recognized in the metamorphic aureole of a hercynian granite; the host rocks are metasedimentary schists and greywacks of the pre-ordovician “Complexo Xisto-Grauváquico”. To assess water-rock interaction 11 groundwater wells were selected and sampled, for major and trace elements as well as for radioisotopes 222Rn, 226Ra, 234U, 238U analyses. Analytical results point to Na-Ca-bicarbonate groundwater with a mean electric conductivity of 477μS·cm−1 and pH between 5.4 and 6.5. The concentration of dissolved arsenic (As) reaches 15μgL−1, mostly in the oxidized form of As(V), and is above the parametric value for drinking water (10μgL−1) in 3 wells used for drinking and/or irrigation. The radioisotope activity (U, 226Ra and 222Rn) is also very high in the most of collected water samples. About 65% of the samples are above the WHO recommended limit for drinking water with respect to U, with a median of 129mg·L−1 and a maximum of 3483mg·L−1. About 30% of the samples are above the EU (2013) recommended limit for drinking water for 222Rn (1000Bq·L−1), with a median of 400Bq·L−1 and a measured maximum of 9784Bq·L−1. The human health impact was evaluated only for the water ingestion vector through calculation of the annual effective dose. As the health impact depends of the body mass the dose was calculate for different age groups of the population. The results indicate that, in 60% of the samples, the effective dose exceeds the limits suggested by existing guidelines. The use of groundwater for drinking and crop irrigation in the studied region should be subject to previous assessment for U, Ra, Rn and As. In the activity concentrations found in the present work they are clearly a potential health risk for the population.

Reply to query related to “Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique”

The queries made by Rathore in the preceding Letter to Editor (J Radioanal Nucl Chem, 2013) regarding the “Studies of ground water contamination in Punjab state in India using X-ray fluorescence technique” by Alrakabi et al. (J Radioanal Nucl Chem 294:221–227, 2012. doi: 10.1007/s10967-011-1585-x), are responded. The points raised by Rathore are important in case of sensitive analytical techniques, where only a small fraction (~few hundred μL of water) of the water sample collected in the container is effectively used as analyte. The biasing due to chemical speciation and physical escape of element of interest becomes significant in such rapid techniques if the ionic species of interest in the analyte are not stabilised using suitable additives. In the reported study based on X-ray fluorescence technique, the analyte used for elemental analysis was obtained by drying about 500–1000 mL of water sample. Adequate precautions were taken to minimize possibility of element of interest to escape or adhere to the bottle surface or lost as residue. The onsite acidification of collected water sample to pH 1 with reagent-grade nitric acid for sample preservation is not a pre-requisite in the procedure followed. The contribution of particulate matter to the reported concentrations of uranium was estimated to be insignificant. Also, the query related to effect of co-precipitation of uranium with formation of CaF2 is found to be inconsequential. The comment made by Rathore (J Radioanal Nucl Chem, 2013) stating that ‘proceeding further in the measurement of uranium is a waste of time and has no meaning and results and discussion have no meaning too’ is extraneous.

Letter to the Editor: Query related to publication titled “Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique” by Alrakabi et al. 294:221–227 (2012), doi:10.1007/s10967-011-1585-x

Dear Editor, I have read the above cited paper very carefully. Undersigned has been involved in the analysis of geological materials and hydro-geochemical reconnaissance surveys attached with mobile geochemical laboratories in different parts of India for uranium exploration activities of Atomic Minerals Directorate for Exploration and Research. Based on my experiences gained so far, I would like to share some of my observations as follows: There are two essential parameters for the reliability of measurement results for naturally occurring water samples:

Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique

The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15 ppb recommended by World Health Organisation for the drinking water, and its values in the canal water samples are below 5 ppb. To investigate the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured potential source of uranium contamination of the ground water.

Uranium(VI) diffusion in low-permeability subsurface materials

Abstract Uranium(VI) diffusion was investigated in a fine-grained saprolite sediment that was collected from U.S. Department of Energy (DOE) Oak Ridge site, TN, where uranium contamination in groundwater is a major environmental concern. U(VI) diffusion was studied in a diffusion cell with one cell end in contact with a large, air-equilibrated electrolyte reservoir. The pH, carbonate and U(VI) concentrations in the reservoir solution were varied to investigate the effect of solution chemical composition and uranyl speciation on U(VI) diffusion. The rates of U(VI) diffusion were evaluated by monitoring the U(VI) concentration in the reservoir solution as a function of time; and by measuring the total concentration of U(VI) extracted from the sediment as a function of time and distance in the diffusion cells. The estimated apparent rate of U(VI) diffusion varied significantly with pH, with the slowest rate observed at pH 7 as a result of strong adsorptive retardation. The estimated retardation factor was generally consistent with a surface complexation model. Numerical simulations indicated that a species-based diffusion model that incorporated both aqueous and surface complexation reactions was required to describe U(VI) diffusion in the low permeability material under variable geochemical conditions. Our results implied that low permeability materials will play an important role in storing U(VI) and attenuating U(VI) plume migration at circumneutral pH conditions, and will serve as a long-term source for releasing U(VI) back to the nearby aquifer during and after aquifer decontamination.

Use of 234 U and 238 U isotopes to evaluate contamination of near-surface groundwater with uranium-mill effluent: a case study in south-central Colorado, U.S.A.

The 234U/238U alpha activity ratio (AR) was determined in 47 samples of variably uraniferous groundwater from the vicinity of a uranium mill near Canon City, Colorado. The results illustrate that uranium isotopes can be used to determine the distribution of uranium contamination in groundwater and to indicate processes such as mixing and chemical precipitation that affect uranium concentrations. Highly to moderately contaminated groundwater samples collected from the mill site and land immediately downgradient from the mill site contain more than 100 μg/l of dissolved uranium and typically have AR values in the narrow range of 1.0–1.06. Other samples from the shallow alluvial aquifer farther downgradient from the mill contain 10–100 μg/l uranium and plot along a broad trend of increasing AR (1.06–1.46) with decreasing uranium concentration. The results are consistent with mixing of liquid mill waste (AR≈1.0) with alluvial groundwater of small, but variable, uranium concentrations and AR of 1.3–1.5. In the alluvial aquifer, the spatial distribution of wells with AR values less than 1.3 is consistent with previous estimates of the probable distribution of contamination, based on water chemistry and hydrology. Wells more distant from the area of probable contamination have AR values that are consistently greater than 1.3 and are indicative of little or no contamination. The methodology of this study can be extended usefully to similar sites of uranium mining, milling, or processing provided that local geohydrologic settings promote uranium mobility and that introduced uranium contamination is isotopically distinct from that of local groundwater.