High Levels Of Uranium Research Articles

Assessment of uranium-235 distribution in soil samples from Anbar province, Western Iraq

Uranium is a radioactive element that can pose a risk to human health if ingested or inhaled. Exposure to high levels of uranium can increase the risk of cancer. Measuring uranium concentration in soil can help identify areas where there may be a risk of exposure to high levels of uranium and take appropriate measures to protect public health. In this study, uranium concentration in soil samples collected from Anbar province in Iraq was measured using CR-39 detectors irradiated with an Am-Be neutron source. The results showed that the highest concentration of uranium-specific activity (12.029 ± 0.0016 Bq kg−1) was found in Al Fallujah district, while the lowest concentration (0.531 ± 0.0007 Bq kg−1) was found in Al Sagra district. Interestingly, the data suggest that uranium concentrations increase as we move southeast towards Baghdad, where the city’s climate is reportedly polluted. Despite this, the average uranium-specific activity level in Anbar (7.668 Bq kg−1) is relatively low, and it falls below the global average of 35 Bq kg−1 recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation. This study concludes that there is no evidence of uranium pollution in Anbar. Although uranium concentrations are considered low, low levels of uranium concentration in soil can have important implications for environmental risk, resource exploration, agricultural productivity, and geological research.

Radioactive remote signatures derived from Sentinel-2 images and field verification in West Sulawesi, Indonesia.

Mamuju, West Sulawesi, is an area in Indonesia with high radiation levels. A high radiation dose rate was detected in Adang volcanic rock. Activities related to radioactive minerals contained in rocks and soil may release hazardous radiation into the environment. The study area generally exhibits a highly irregular morphology that provides limited access because of the high slope gradient of the volcanic terrain. Therefore, it is challenging to identify and map minerals carrying radioactive elements via Sentinel-2 remote sensing. Since optical satellite images are superior in land cover detection, we proposed a mapping technique for radioactive carrier minerals based on vegetation indices verified by chlorophyll field measurements. We applied band rationing to identify the distribution of hydrothermal alteration minerals and vegetation stress, while field chlorophyll measurements of Dryopteris marginalis and Nephrolepis exaltata were conducted. The Sentinel-2 color composite of images with 4/2, 8A/11, and 11/12 RGB band ratios revealed the distribution of iron oxide, ferromagnesian silicates, and clay minerals. High levels of uranium (U) were scattered in leucite basalt rocks, with a broad distribution of iron oxide minerals and small amounts of ferromagnesian minerals. In contrast, the presence of thorium was not affected by the presence of these minerals. In addition, band rationing of chlorophyll spectra captured by the red edge vegetation index (REVI) was used as the basis for vegetation stress mapping related to radiation exposure based on the chlorophyll content in ferns in the study area. The REVI image showed an anomalous vegetation stress concordant with the high radioactivity. To obtain more accurate results, ground measurements were also performed to identify the vegetation stress due to the presence of minerals carrying radioactive elements. The areas with radioactive mineralization and vegetation stress were located upstream of the Mamuju River and the Botteng and Ahu areas in Tapalang.

Hydrogeochemical constraints on uranium contamination of groundwater for drinking water supplies and associated health risks

The groundwater quality of Punjab, India is of huge concern owing to the presence of various toxic contaminants that includes uranium and other trace elements. The focus of this study is to identify the hydrogeochemical processes responsible for uranium mobilization in groundwater and evaluation of groundwater quality in uranium contaminated zones for drinking, irrigation use along with associated health risks. The study was conducted using the water quality data obtained from 302 sampling locations covering the entire state of Punjab reported by Central Ground Water Board between 2019 and 2020. It was observed that around 50% of the samples were exceeding the drinking water acceptable limits for total alkalinity, magnesium, pH, and Total Dissolved Solids. Around 25% of the samples were above drinking water acceptable limit for uranium in groundwater. A comprehensive multiplicative water quality index (MED-WQI) well represented the consolidated perspective of all individual water quality parameters wherein 40 sampling locations in districts viz. Bathinda, Fazilka, Ferozepur, Jalandhar, Kapurthala, Ludhiana, Muktsar and Sangrur fall under heavily-polluted water quality class due to high levels of uranium, alkalinity, and hardness. The Piper plots and Gibbs diagram depicted that the majority of groundwater samples were characterized as Na+–HCO3−, Ca2+–Mg2+–HCO3− systems driven by rock-water interactions. Speciation analysis indicates that the dominant uranium species in groundwater of U-affected regions was primarily associated with calcium and alkalinity and exist in the form of CaUO2(CO3)32−, Ca2UO2(CO3)3(aq), UO2(CO3)34−, and UO2(OH)3−. Various irrigation indices depict that the groundwater in majority of the state, barring few districts in Malwa region, was suitable for irrigation. Further, a non-carcinogenic health risk assessment model showed association of high health risk with heavily-polluted water quality class. The results of this study would aid regulatory authorities in designing remedial strategies and frame policy actions toward groundwater quality improvement in the uranium-affected regions of Punjab.

Geogenic controls on the high levels of uranium in alluvial aquifers of the Ganga Basin

The Indo-Gangetic Basin (IGB) alluvial aquifer system provides a reliable drinking water supply to over half a billion people. Understanding the groundwater quality, aquifer processes, groundwater storage, and depletion trends in the IGB alluvial aquifer system— one of the world's most important freshwater resources has been the focus of many previous studies. However, understanding what governs uranium variability in the IGB alluvial aquifer system— for example, whether uranium is released from natural deposits or anthropogenic sources such as mill tailing, emissions from the nuclear industry, combustion of fossil fuels, and phosphate fertilizers— are under-explored but critically important for constraining the environmental fate of uranium. Here, we present surface and groundwater uranium concentration data in the central parts of the IGB alluvial aquifer system. We find a high concentration of groundwater uranium above the World Health Organization provisional guideline value of 30 μg/L in 17% (n = 29) of collected groundwater samples, whereas other heavy metals, namely Cr, Ni, Pb, and Cd were within the recommended range. Trace element systematic demonstrates that anomalous uranium enrichment is primarily derived from geogenic sources, while uranium mobility is predominantly controlled by the alkalinity (a proxy for bicarbonate), hence by soluble uranyl carbonate complexes. As in the year 2020, the Bureau of Indian Standard incorporated uranium as a possible drinking water contaminant, our dataset calls for additional assessments of groundwater uranium concentrations in Indian groundwater resources because uranium concentration data are scarce compared to other geogenic contaminants such as arsenic and fluoride. We conclude that uranium, like arsenic and fluoride, is also critical geogenic contaminant in the alluvial aquifers that needs to be better monitored as higher levels of uranium in drinking water have adverse health effects.

Behavior of uranium series in groundwater of the Wajid Formation, Wadi AdDawasir, Saudi Arabia.

The inventories and the possible mechanisms behind the relative deficiency of both radium and uranium release processes within an elevated gamma-anomalous rock were investigated. A field survey was performed on the highest radioactive anomalous zone that was recorded at Jabal Al Alam (20° 13' 10.06″ N and 44° 14' 32.13″), with the ferruginous sandstone, iron oxide band, and iron concretions (with uranium content and reaching up to1500 ppm). The chemical analyses and the laboratory's gamma-ray spectrometric measurements demonstrated high uranium levels in the analyzed rock samples of the Wajid Sandstone (up to 1000 ppm). The borehole geophysical logs further confirmed that the radioactive anomalies are attributed to the sandstone sequence of the Wajid Formation that is often found associated with elevated concentrations of uranium. The groundwater samples taken from the wells tapping the Wajid aquifer showed uranium concentrations ranging from 0.01 to 5.5 ppb (μg/L). The average 226Ra in groundwater samples was 0.2 Bq L-1. The majority of the 226Ra and 228Ra activities were below the lower limit of detection (LLD). The radiochemical analyses of water samples from the Wajid aquifer display low concentrations of both uranium and 226Ra, with relation to uranium content in host rocks. This was attributed to the fact that uranium is susceptible to form iron oxide complexes, causing them to precipitate in a more stable form. Furthermore, iron oxides coat the sand grains of the Wajid Formation and accordingly might act as a foundation for re-adsorption for both uranium and radium, resulting in their relative deficiency in the surrounding water. The coating might also act as a physical barrier resulting in hindrance of the recoil nuclei due to its significant thickness (several orders of magnitude) compared with that of the average (120 nm) whole alpha-recoil track (ART). The coating layer thickness was determined via scanning electron microscopy (SEM) and was found to be up to 180 μm.

Assessment of Radon Concentration and Impact on Human Health in a Region Dominated by Abandoned Gold Mine Tailings Dams: A Case from the West Rand Region, South Africa

Radon gas has long been identified as a human carcinogen. The purpose of this study was to understand the occurrence of radon gas in the West Rand region, located west of the city of Johannesburg, South Africa, and to investigate its potential health effects. In this study, the sampling of rocks, tailings, and construction materials was carried out for geochemical analyses. For characterisation of radon, 60 radon monitors (RGMs) were installed in indoor and outdoor environments. The results showed that mine tailings contain high uranium levels, with a maximum of 149.76 ppm and a mean value of 48.87 ppm. The radon levels in the area ranged between 32 Bq/m3 and 1069 Bq/m3 and thus, exceed the typical outdoor radon levels of about 10 Bq/m3. Significantly high values were obtained from gold tailings dams. In indoor environments, radon concentration ranged up to a maximum of 174 Bq/m3, which is above the recommended value of 100 Bq/m3. The effective doses calculated from the obtained radon levels showed a maximum of 16 mSv/y, which is above the recommended value of 1 mSv/y proposed for public exposure. The estimated doses have an enormous potential to pose high lung cancer risks to the populations residing nearby tailings.

Selenium Contamination of Groundwater of Malwa Belt of Punjab (India)

Punjab is facing a crisis situation due to high levels of uranium, arsenic and selenium in underground water table of Punjab. Malwa belt of Punjab, namely, Ludhiana, Ferozepur, Roop Nagar and Fatehgarh sahib districts have high selenium contents in groundwater. Selenium Acceptable Limit (AL) for groundwater is fixed at 0.01 mg/l (ppm) by the Bureau of Indian Standards (BIS). In this report, groundwater quality data pertaining to selenium in the Malwa belt is reported. The highest value of selenium content of 0.14 mg/l (ppm) was reported in the water drawn from a handpump in the village Urna of Ludhiana district. Out of 80 villages of Ludhiana district with selenium content above AL value, 38 have selenium contamination levels higher than 0.015 mg/l (ppm). Roop Nagar, Ferozepur and Fatehgarh Sahib districts have 29, 9 and 17 villages with selenium content above the AL value, respectively. The possible health hazard effects of selenium are reported on the basis of studies carried out in the USA, China and Italy. Keywords: Selenium, acceptable limit, Malwa belt of Punjab, health hazards of Selenium Cite this Article Virk HS. Selenium Contamination of Groundwater of Malwa Belt of Punjab, India. Research & Reviews: A Journal of Toxicology . 2019; 9(1): 13–20p.

The mapping and investigation of radionuclide pollution in the processing plant of a spent phosphate mine by using GIS techniques

The mining and refinement of phosphate is characterised by high levels of uranium. An in situ gamma ray survey was done at the processing plant of a spent phosphate mine near Vredenburg on the west coast of South Africa in order to assess radionuclide concentrations. The concentrations of potassium, thorium and radioactive progeny of uranium were measured and plotted with the help of QGIS software. The results demonstrated high concentrations in specific areas of the plant. The highest concentrations were found to be 898 Bg/kg for potassium, 162 Bg/kg for 232 Th and 639 Bg/kg for 226 Ra. It was demonstrated that the refinement process technologically enhanced the naturally occurring radioactive nuclides and contaminated sections of the processing plant. The causes of the contamination was also investigated. The effective dose for the various parts of the processing plant was also estimated and the highest level was found to be 0.45 mSv/y. The article finally draws conclusions as to the environmental impact of the radiation and possible future preventative measures that could be followed in order to minimize pollution.

Minimal uranium accumulation in lymphoid tissues following an oral 60-day uranyl acetate exposure in male and female C57BL/6J mice.

High levels of uranium (U) exist in soil, water, and air in the Southwestern United States due, in part, to waste generated from more than 160,000 abandoned hard rock mines located in this region. As a result, many people living in this region are chronically exposed to U at levels that have been linked to detrimental health outcomes. In an effort to establish a relevant in vivo mouse model for future U immunotoxicity studies, we evaluated the tissue distribution of U in immune organs; blood, bone marrow, spleen, and thymus, as well as femur bones, kidneys, and liver, following a 60-d drinking water exposure to uranyl acetate (UA) in male and female C57BL/6J mice. Following the 60-d exposure, there was low overall tissue retention of U (<0.01%) at both the 5 and the 50 ppm (mg/L) oral concentrations. In both male and female mice, there was limited U accumulation in immune organs. U only accumulated at low concentrations in the blood and bone marrow of male mice (0.6 and 16.8 ng/g, respectively). Consistent with previous reports, the predominant sites of U accumulation were the femur bones (350.1 and 399.0 ng/g, respectively) and kidneys (134.0 and 361.3 ng/g, respectively) of male and female mice. Findings from this study provide critical insights into the distribution and retention of U in lymphoid tissues following chronic drinking water exposure to U. This information will serve as a foundation for immunotoxicological assessments of U, alone and in combination with other metals.

A Crisis Situation Due to Uranium and Heavy Metal Contamination of Ground Waters in Punjab State, India: A Preliminary Report

Punjab is facing a crisis situation due to high levels of uranium (U) and heavy metals in underground water table of Punjab. Uranium poisoning in Punjab first made news in March 2009, when a South African Clinical Metal Toxicologist, Carin Smit, visiting Faridkot city in Punjab found surprisingly high levels of uranium in 88% of the blood samples collected from the Baba Farid Centre for Special Children in the Malwa region of Punjab. In this preliminary report, groundwater quality data pertaining to uranium and heavy metals, such as iron, nickel, cadmium, mercury, chromium, aluminium, lead, arsenic and selenium, are reported. A bird's eye view of survey report on groundwater contamination by basic parameters, such as TDS (total dissolved salts), calcium, magnesium, sulphate, nitrate, chloride and fluoride, is also given. The final report enumerating the health hazard effects of heavy metals on population in Punjab will be presented after compiling the data analysis. Keywords: Heavy metal contamination, Uranium, Punjab Cite this Article Hardev Singh Virk. A Crisis Situation Due to Uranium and Heavy Metal Contamination of Ground Waters in Punjab State, India: A Preliminary Report. Research & Reviews: A Journal of Toxicology. 2017; 7(2): 6–11p.

Zebrafish exposure to environmentally relevant concentration of depleted uranium impairs progeny development at the molecular and histological levels.

Uranium is an actinide naturally found in the environment. Anthropogenic activities lead to the release of increasing amounts of uranium and depleted uranium (DU) in the environment, posing potential risks to aquatic organisms due to radiological and chemical toxicity of this radionucleide. Although environmental contaminations with high levels of uranium have already been observed, chronic exposures of non-human species to levels close to the environmental quality standards remain scarcely characterized. The present study focused on the identification of the molecular pathways impacted by a chronic exposure of zebrafish to 20 μg/L of DU during 10 days. The transcriptomic effects were evaluated by the use of the mRNAseq analysis in three organs of adult zebrafish, the brain the testis and the ovaries, and two developmental stages of the adult fish progeny, two-cells embryo and four-days larvae. The results highlight generic effects on the cell adhesion process, but also specific transcriptomic responses depending on the organ or the developmental stage investigated. The analysis of the transgenerational effects of DU-exposure on the four-day zebrafish larvae demonstrate an induction of genes involved in oxidative response (cat, mpx, sod1 and sod2), a decrease of expression of the two hatching enzymes (he1a and he1b), the deregulation of the expression of gene coding for the ATPase complex and the induction of cellular stress. Electron microscopy analysis of skeletal muscles on the four-days larvae highlights significant histological impacts on the ultrastructure of both the mitochondria and the myofibres. In addition, the comparison with the transcriptomic data obtained for the acetylcholine esterase mutant reveals the induction of protein-chaperons in the skeletal muscles of the progeny of fish chronically exposed to DU, pointing towards long lasting effects of this chemical in the muscles. The results presented in this study support the hypothesis that a chronic parental exposure to an environmentally relevant concentration of DU could impair the progeny development with significant effects observed both at the molecular level and on the histological ultrastructure of organs. This study provides a comprehensive transcriptomic dataset useful for ecotoxicological studies on other fish species at the molecular level. It also provides a key DU responsive gene, egr1, which may be a candidate biomarker for monitoring aquatic pollution by heavy metals.

Health Effects and Environmental Justice Concerns of Exposure to Uranium in Drinking Water.

We discuss the recent epidemiologic literature regarding health effects of uranium exposure in drinking water focusing on the chemical characteristics of uranium. While there is strong toxicologic evidence for renal and reproductive effects as well as DNA damage, the epidemiologic evidence for these effects in people exposed to uranium in drinking water is limited. Further, epidemiologic evidence is lacking for cardiovascular and oncogenic effects. One challenge in characterizing health effects of uranium in drinking water is the paucity of long-term cohort studies with individual level exposure assessment. Nevertheless, there are environmental justice concerns due to the substantial exposures for certain populations. For example, we present original data suggesting that individuals living in the Navajo Nation are exposed to high levels of uranium in unregulated well water used for drinking. In 10 out of 185 samples (5.4%), concentrations of uranium exceeded standards under the Safe Drinking Water Act. Therefore, efforts to mitigate exposure to toxic elements in drinking water are warranted and should be prioritized.

Comparative proteomics of Acidithiobacillus ferrooxidans grown in the presence and absence of uranium

Acidithiobacillus ferrooxidans is an acidophile that thrives in metal-contaminated environments and tolerates high levels of uranium. To gain a better understanding of the processes involved in U(VI) resistance, comparative proteomics was used. The proteome of A. ferrooxidans was grown in the presence and absence of 0.5 mM U(VI); expression of 17 proteins was upregulated and one was downregulated. Most proteins with increased expression are part of the general stress response or are involved in reactive oxygen species detoxification. Four novel proteins showed increased expression in the presence of U(VI) and may contribute to U(VI) resistance via thiol homoeostasis and U(VI) binding.

In situ gamma ray measurements of radionuclides at a disused phosphate mine on the West Coast of South Africa

High levels of uranium and its radioactive progeny like radium is normally associated with phosphate mining. In Situ gamma ray spectroscopy as a survey tool has been successfully applied to assess radionuclide concentrations in various geographical environments. A transportable and robust gamma ray detection system (GISPI) was therefore employed to determine the concentrations of naturally occurring radionuclides at a disused phosphate mine on the West Coast of South Africa. The concentrations of radium, thorium and potassium were measured and plotted. The measurements showed fairly high concentrations with medians of 320 Bq/kg for 226Ra, 64 Bq/kg for 232Th and 390 Bq/kg for 40K. The highest concentrations were however confined to specific areas of the mine. The effective dose due to gamma irradiation for the various areas of the mine was also estimated and the highest estimated level was 0.45 mSv/y. The article finally draws conclusions as to the origins and impact of the radiation.

Biomineralization of uranium by PhoY phosphatase activity aids cell survival in Caulobacter crescentus.

Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria.

Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China

Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally <1mg/kg for the igneous and metamorphic rocks, typically 2–5mg/kg for the Carboniferous and Permian sedimentary rocks and around 3mg/kg for sediments and topsoil, respectively. U in the Quaternary aquifer sediments may be primarily associated with carnotite from the Carboniferous and Permian coal-bearing clastic rocks around the basin. Shallow groundwater had U concentrations of <0.02–288μg/L (average 24μg/L), with 24% of the investigated boreholes above the WHO provisional guideline of 30μg/L for U in drinking water. Average U concentration for surface water was 5.8μg/L. In oxidizing waters, uranyl (UO22+) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (>30μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (>100μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca2UO2(CO3)3 in the dominant Ca–Mg–Na–HCO3 type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater.

Community level physiological profiles of bacterial communities inhabiting uranium mining impacted sites

Bacterial activity and physiological diversity were characterized in mining and milling impacted soils collected from three abandoned uranium mine sites, Senokos, Buhovo and Sliven, using bacterial dehydrogenase activity and Biolog (EcoPlate) tests. The elemental composition of soils revealed high levels of uranium and heavy metals (sum of technogenic coefficients of contamination; TCCsum) pollution as follows: Sliven (uranium – 374mg/kg; TCCsum – 23.40) >Buhovo (uranium – 139.20mg/kg; TCCsum – 3.93) >Senokos (uranium – 23.01mg/kg; TCCsum – 0.86). The physiological profiles of the bacterial community level were site specific, and indicated intensive utilization of polyols, carbohydrates and carboxylic acids in low and medium polluted environments, and i-erithrytol and 2-hydroxy-benzoic acid in the highly polluted environment of Sliven waste pile. Enzymes which take part in the biodegradation of recalcitrant substances were more resistant to pollution than these from the pathways of the easily degradable carbon sources. The Shannon index indicated that the physiological diversity of bacteria was site specific but not in line with the levels of pollution. A general tendency of increasing the importance of the number of utilizable substrates to bacterial physiological diversity was observed at less polluted sites, whereas in highly polluted sites the evenness of substrate utilization rate was more significant. Dehydrogenase activity was highest in Senokos upper soil layer and positively correlated (p<0.01) with the soil organic matter content. The bacterial activity (EcoPlate) and physiological diversity (Shannon index) correlated significantly and negatively with As, Cu, Zn, Pb and U, and Co, Cr, Ni and Mn, respectively. We concluded that the observed site specific shifts in bacterial communities were complex due to both the environmental peculiarities and the bacterial tolerance to the relevant level of pollution, rather than a strong indication of uranium and heavy metals toxicity.

복운모화강암지역 지하수 중 자연방사성 물질의 경시적 붕괴특성 연구

To figure out the decay characteristics of naturally occurring radionuclides, eight sampled groundwaters from a monitoring borehole having high levels of uranium and radon concentrations in a two mica granitic area have analyzed by liquid scintillation counters (LSC) for over 1 year. In December 2011, three groundwater samples (DJ1, DJ2, DJ3) were obtained from each aquifer system located at -20 m, -40 m, -60 m of the monitoring borehole below the ground surface, respectively. Five samples (DJ4, DJ5, DJ6, DJ7, DJ8) were additionally gained from each aquifer positioned -20 m, -40 m, -60 m, -100 m, -105 m of the borehole in February 2012, respectively. Temporal variation characteristics of uranium and radon concentrations have showed over maximum 2.1 times and 1.4 times fluctuations of the values in the same sampling intervals over time, respectively. The intervals of -40 m and -105 m in the borehole have the highest values of uranium and radon concentrations, respectively. This may imply that the concentrations of naturally occurring radionuclides such as uranium and radon in groundwater have been changed over time and indicate that the qualities of groundwaters from the aquifers developed at each interval in the borehole are different each other. This discrepancy, moreover, could be caused by behaviour differences between uranium which is in ionic status having a half life of 4.6 billion years and is transported along with the flowing groundwater, and radon which is in gaseous status having a 3.82 day's half life in the aquifer systems. Physicochemical characteristics of groundwaters from the aquifer systems could be identified by the results of the on-situ measuring items such as pH and Eh, and the major ionic contents. The CPM values of eight groundwater samples analysed by LSC over one year have shown not to follow the theoretical decay curve of the radon. The CPM values of the samples have ranged from 2 to 7.5 after it had passed two months when the theoretical CPM values of the radon started zero since the initial analysis. Alpha and beta particle spectrums have shown the peaks of radium-226, however they have not revealed any peaks of radon and it's daughter products such as polonium-218 and 214, bismuth-214 for the late stage of the analysis. This implies that the groundwater from the borehole may contain radium-226 having a half life of 1,600 years which decays continuously.

Co-occurrence of High Levels of Uranium, Arsenic and Molybdenum in Groundwater of Dornogobi, Mongolia

Co-occurrence of High Levels of Uranium, Arsenic and Molybdenum in Groundwater of Dornogobi, Mongolia

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.