Uranium Concentration In Water Research Articles

A Study on the Possible Relationship between Physico-Chemical Properties of the Covering Soil and the Mobility of Radionuclides and Potentially Toxic Elements in a Recultivated Spoil Bank

This study is part of the ongoing environmental monitoring program of the abandoned Mecsek uranium mine. On the mine’s recultivated spoil deposit No. I, anomalies that refer to possible migration alongside the slope were detected. The present study was conducted to supplement the ongoing monitoring study with a sampling strategy and analytical methods that can characterize the mobility of potentially toxic elements and radionuclides. A sampling strategy was developed: the vegetation and soil core samples were collected from the slope from top to bottom of the deposit, and nearby this spoil deposit, water samples were collected. Elemental analyses were conducted: the pseudo-total analysis, a total concentration of uranium in water, and the BCR sequential extraction analysis. The radionuclides were determined by gamma spectrometry and alphaGUARD. Additionally, the soil and plant moisture content, soil organic matter, pH, and cation exchange capacity (CEC) were determined. The Pearson correlation analysis and the principal component analysis, considering all possible influencing factors, verified that the elemental concentration increase from the top to the bottom direction of the deposit is strongly influenced by the soil pH, CEC, and Ca content. The mobility of Cd, Co, Mn, Pb, and U is relatively high and significantly migrates down the slope.

Issues of establishing the permissible discharge levels of <sup>238</sup>U to surface waters taking into account its radiation and toxic effects

At present, discharges of 238U to surface waters by nuclear industry enterprises are limited by radiation factor. Registration and control of 238U discharges to water bodies is performed in units of radioactivity (Bq/year) according to the current permit for the water discharge of radioactive substances. At the same time, uranium belongs to the 1st hazard class by its chemical toxicity (extremely dangerous chemicals), it has hygienic standard for content in surface waters. A comparison was made for the limitation of 238U intake to surface waters, taking into account radiation exposure and chemical toxicity. Activity concentration of 238U in water was calculated, at which the annual dose for a critical population group from water use would be 0,1 mSv/year (scenario 1 – the water object is used for drinking water supply) or 1 mSv/year (scenario 2 – the water object is not used for drinking water supply). The calculated activity concentrations were expressed in units of mass concentrations and compared with the maximum permissible concentration of uranium in water, established in Russia, 15 mkg/L. It is shown that compliance with the radiation safety norms does not automatically guarantee compliance with the current hygienic standards for limiting the toxic effects of uranium on population and the environment. The concentration of 238U in water producing the annual dose to population 0,1 mSv taking into account all exposure pathways, exceeds the maximum permissible concentration of uranium in water by 15 times. If water body is not used for drinking water supply, the calculated concentration of 238U in water producing the annual dose to population 1 mSv, is higher than the maximum permissible concentration of uranium in water by 1500 times. The restrictions imposed by the current hygienic standards for the chemical toxicity of uranium could reduce the permissible discharge levels of 238U to surface waters. It is necessary to develop environmental quality standards for 238U, taking into account its chemical toxicity, and include them to the system of establishment of permissible discharge limits of radioactive substances.

Assessment of Uranium Concentrations in Drinking Water Supply Sources Based on the Results of Laboratory Analysis of 238U and 234U Specific Activities and Laboratory Determination of Uranium According to GOST R 54499–2011

Introduction. The cause of toxicity and damaging effects of uranium and its compounds on the body lies in radioactivity of uranium isotopes and their decay products as well as their high chemical activity. In view of the above, we conducted parallel studies of specific activities and concentrations of uranium in household and drinking water supply sources. Materials and methods. We studied specific activities of uranium-234 and uranium-238 in the centralized drinking water supply sources of the Republic of Khakassia exceeding control levels in terms of specific total alpha activity (Aα) and converted them to mass concentrations of uranium. Parallel analyses of uranium concentrations in water using the luminescent method according to GOST R 54499–2011 were performed. Results. Our assessment of the radionuclide composition of centralized drinking water supply sources showed that Aα levels exceeding control levels were largely due to natural radionuclides uranium-238 (contribution up to 25%) and uranium-234 (contribution up to 69%). Based on the specific activities of uranium-234 and uranium-238, we estimated masses (concentrations) of uranium in water ranging from 0.007 to 0.06 mg/L depending on the water source. In the parallel tests of water samples according to GOST R 54499–2011, uranium concentrations ranged from 0.007 to 0.061 mg/L. Conclusions. The uranium concentrations in the republican centralized drinking water supply sources estimated on the basis of uranium-234 and uranium-238 specific activities differed from the concentrations of uranium measured by the luminescent method according to GOST R 54499–2011 within the error of the test method. In some settlements uranium concentrations in water exceeded the hygienic standard of 0.015 mg/L (GN 2.1.5.2280–07).

Association between Uranium Exposure and Thyroid Health: A National Health and Nutrition Examination Survey Analysis and Ecological Study.

Besides specific, incidental radiation exposure, which has been associated with increased thyroid cancer risk, the effects of exposure to background radiation from uranium, a naturally occurring, radioactive, and ubiquitous element, on the thyroid gland has not been widely studied. We therefore investigated the association between uranium exposure and thyroid health in the US. Using the National Health and Nutrition Examination Survey (NHANES), we assessed the association between urinary uranium levels and thyroid-related antibodies, including thyroglobulin antibodies (TgAb) and anti-thyroid peroxidase (anti-TPO), in the general population. Secondly, we performed an ecological study of age-adjusted thyroid cancer incidence rates per state and sources of uranium exposure. We included 3125 eligible participants from the NHANES and found a significant association between increased TgAb and increased urinary uranium levels when analyzed as quartiles (p = 0.0105), while no association was found with anti-TPO. In addition, although no significant correlation was found in the ecological study, certain states had high age-adjusted thyroid cancer incidence rates and a high number of uranium activity locations and high uranium concentrations in water. The present study suggests that uranium exposure may affect thyroid health, which warrants increased sampling of soil and water in high-risk states.

Determination of uranium in aqueous solutions by the time-of-flight mass-spectrometry with a pulsed glow discharge after its accumulation on the oxidized carbon nanotubes

The pollution of the environment with uranium dictates the need to control the concentration of this element in natural waters to the permissible limits for the stability of the ecosystems and public health. In 2011, WHO set maximum permissible concentration of uranium in water to 0.03 ppm due to the strong toxicity and radioactivity of uranium in water. Therefore, the continuous monitoring of uranium content is an important task for the safety and health of the citizens. To determine the low uranium content in natural waters, the conservation of the studied solutions is necessary. However, this method of storage and transportation is not always simple. In the current paper, as a convenient method of concentrating uranium, preserving the sample and transporting it, we used the method of sorbing uranium on sorbents. Single-layer carbon nanotubes were used as sorbents. Their surfaces were modified using wet chemical oxidation and synthesis with Aerosil A-380 silica. Two schemes were considered for concentrating the uranium on the surface of the sorbent: individual carbon nanotubes and nanotubes modified with silica. The direct analysis was used to determine the content of uranium in the sorbent, namely, time-of-flight mass spectrometry with the pulsed glow discharge (GDMS). The most effective approach for the determination of uranium in water was the sorption of uranium on the tablet consisting of oxidized nanotubes modified with silica. The limit of detection in this case was 0.2 ppb. Keywords : mass-spectrometry, pulsed glow discharge, environment, direct analysis, uranium, carbon nanotubes DOI: http://dx.doi.org/10.15826/analitika.2020.24.2.001 T itova A.D 1 , Postnov V.N. 1 , Savinov S.S. 1 , Stolyarova N.V. 2 , Ivanenko N.B. 2 , Chuchina V.A. 1 , Gubal A.R. 1 , Ganeev A.A. 1,2 1 Saint-Petersburg State University (SPBU), Universitetskaya emb., 7/9, Saint-Petersburg, 199034, Russian Federation 2 Institute of Toxicology of Federal Medico-Biological Agency, ul. Bekhtereva, 1, Saint-Petersburg, 192019, Russian Federation

Flow period influence on uranium and trace elements release in water from the waste rock pile of the former La Commanderie uranium mine (France)

Uranium mining activities expose uranium ore and mine tailings to the surface environment, where the release of radionuclides is facilitated by weathering at rates exceeding those typically found in nature. Therefore, close to former uranium mining sites, radionuclides and especially uranium concentrations in water may surpass local background levels. The methodology proposed herein, entails coupling, gamma-ray mapping, water sampling and chemical analyses including DGT (Diffusive Gradient in Thin Film) measurements, provides new insights into describing the environment of the La Commanderie site (France). Gamma-ray mapping allows identifying water seepage, output from a waste rock pile, as a potential pathway for radionuclides into the environment. Water seepage monitoring has shown: a low pH value (4.2), high sulfate content (179 mg.L−1) and high uranium concentrations of up to 436 μg.L−1. These recordings indicate that an acid mining drainage (AMD) process is occurring inside or under the oxidized parts of the waste rock pile. Monitoring data over three flow periods revealed the release of the highest uranium concentrations during a high-flow period downstream of the site, which is compliant with local regulations. The AMD process is also responsible for the release of significant amounts of Fe, Mn and As within the immediate environment in both dissolved and particulate forms. Changes in dissolved oxygen concentration and redox potential during low flow periods, modify the speciation of Fe (in AMD waters) which acts as a scavenger for other elements such as As, Mn and U. The use of DGT under environmental conditions, and specifically AMD waters, seems to be relevant in comparison to filtered spot water sampling strategies. Moreover, based on DGT measurements, the dissolved part of the released uranium is considered as labile with concentrations above the environmental standards for freshwater organisms.

Radon and uranium concentration in ground water of nineveh plain region in iraq

The track registration technique with a CR-39 detector was used to measure radon concentrations, and uranium contents in ground water samples from the Nineveh plain region wells. Samples were selected from 20 locations for measurements. This research aimed to assess radiological risks from uranium ingestion, and measure annual effective dose AED resulting from the intake of radon in the ingested water. Radon concentrations in these water samples were found to vary from 0.362 to 1.485 BqL−1, which were below the safety recommended limits 4 to 40 BqL−1 based on the Scientific Committee of United Nations on Atomic Radiation Effects. AED was found to vary from 1.32 to 5.42 µSv/y. Uranium activity concentrations ranged from 0.356 to 1.488 BqL−1, and the corresponding uranium concentrations in water samples were found to vary from 28.76 to 120 μgL−1. Uranium concentrations were over the safety recommended limits when, compared with recommended limits of of 30 μgL−1 for drinking water based on the US environmental protection agency. The excess cancer risk varied from 0.398 to 1.666 x10-4 with a mean value of 0.9 x10-4, indicating that 9/100,000 people in these areas haves a cancer risk from the water.

Assessment of uranium concentration in the drinking water and associated health risks in Eastern Haryana, India

ABSTRACTQuantification of uranium in drinking water has great significance considering its effects on human health. Drinking water samples collected from different sources, viz., hand pumps, tube-wells, and public water supply from Sonipat and Panipat districts of Haryana, India have been analyzed for uranium and other physico-chemical parameters. Uranium concentration in water samples was measured using Pulsed LED Fluorimeter. Uranium concentration in collected water samples ranges from 9.1 to 155.1 µg/L in Sonipat district and 14.9 to 123.3 µg/L in Panipat district. It was inferred from the data that uranium concentration in some water samples was higher than WHO & USEPA recommended limit of 30 µg/L. The mean cancer risk due to uranium in drinking water in Sonipat and Panipat districts was found to be 1.40 × 10−4 and 1.63 × 10−4, respectively, which is lower than the maximum permissible limit (<10−3). Total Dissolve Salts (TDS) in water samples of some villages in Sonipat district was higher than permissible limits for drinking prescribed by WHO & BIS.

Monitoring of uranium concentrations in water samples collected near potentially hazardous objects in North-West Tajikistan

The water contamination near ecologically problematic objects was investigated between 2009 and 2014 in North-West Tajikistan as a part of a joint project between Forschungszentrum Jülich and Khujand State University. The main part of this work was the determination of uranium in water samples collected near the Degmay tailings dump, the Taboshar pit lake and the Syr Darya river. More than 130 water samples were collected and analyzed to monitor the uranium concentration near the investigated areas. Two different mass spectrometers and an ion chromatograph were used for element concentration measurements. Based on the results obtained, the uranium influence of the Degmay tailings on the rivers Khoja-Bakyrgan-Say and Syr Darya and surrounding water was not found. The uranium concentration in water samples was monitored for a lengthy period at seven locations Great differences in the uranium concentration in waters collected in 2010, 2011, 2012, 2013 for each location were not observed. Drinking water samples from the region of North-West Tajikistan were analyzed and compared with the World Health Organization's guidelines. Seven out of nine drinking water samples near Taboshar exceeded the WHO guideline value for uranium concentrations (30 μg/L). The average uranium concentration of water samples from Syr Darya for the period from 2009 to 2014 was determined to be 20.1 (±5.2) μg/L. The uranium contamination of the Syr Darya was determined from the western border to the eastern border and the results are shown in this paper.

Radiological impact of surface water and sediment near uranium mining sites

The aim of this study is to assess the radiological impact of surface water and sediment around uranium mining sites 20 years after their closing. The areas under observations are 31 former classical underground uranium mining and exploratory sites in Bulgaria, named as objects. The extraction and processing of uranium ores in the Republic of Bulgaria were ended in 1992. To assess the radiological impact of radionuclides field expeditions were performed to sample water and bottom sediment. The migration of uranium through surface water was examined as one of the major pathways for contamination spread. The range of uranium concentration in water flowing from the mining sites was from 0.012 to 6.8 mgU l−1 with a geometric mean of 0.192 mgU l−1. The uranium concentrations in water downstream the mining sites were approximately 3 times higher than the background value (upstream). The concentrations of Unat, 226Ra, 210Pb, and 232Th in the sediment of downstream river were higher than those upstream by 3.4, 2.6, 2, and 1.7 times, respectively. The distribution coefficient of uranium reflects its high mobility in most of the sites. In order to evaluate the impact on people as well as site prioritization for more detailed assessment and water management, screening dose assessments were done.

Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA

The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. The (234U)/(238U) composition of Red Rock Creek is altered downstream of the Juniper Mine. As a result of mine-derived contamination, water (234U)/(238U) ratios are 67% lower than in water upstream of the mine (1.114–1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activity ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041–1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (∼70–80% of uranium in leachable fraction). Contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.

Accumulation of uranium by aquatic plants in field conditions: Prospects for phytoremediation

A study was undertaken to determine Uranium concentrations in water and aquatic plants in the uraniferous region of Beiras, Central Portugal. Samples were collected from running water (n=200) at places where aquatic species were observed. Plant samples were collected from 28 species of submerged, free-floating and rooted emergent plants including 2 bryophytes and 1 pteridophyte. Uranium concentrations in surface waters ranged from 0.23 to 1217μgL−1. The aquatic plant species studied, including several previously untested species, exhibited the ability to accumulate U in concentrations many times that of the ambient water. In general submerged plants exhibited higher U content followed by rooted emergent and free floating species. The highest U concentrations were observed in the bryophyte Fontinalis antipyretica (up to 4979mgkg−1) followed by Callitriche stagnalis (1963mgkg−1), Callitriche hamulata (379mgkg−1), Ranunculus peltatus subsp. saniculifolius (243mgkg−1), Callitriche lusitanica (218mgkg−1), and Ranunculus trichophyllus (65.8mgkg−1). In two out of three rooted emergent species U seemed to be preferentially partitioned in rhizome/roots with highest rhizome U content recorded in Typha latifolia (380mgkg−1). Among the free-floating species, the highest U content (42.5mgkg−1) was seen in Lemna minor. The bryophyte F. antipyretica and Callitrichaceae members seem to be promising candidates for the development of phytofiltration methodologies based on U accumulation, abundance and biomass production.

New resin gel for uranium determination by diffusive gradient in thin films technique

A new resin gel based on Spheron-Oxin ® chelating ion-exchanger with anchored 8-hydroxyquinoline functional groups was tested for application in diffusive gradient in thin film technique (DGT) for determination of uranium. Selectivity of uranium uptake from model carbonate loaded solutions of natural water was studied under laboratory conditions and compared with selectivity of the conventional Chelex 100 based resin gel. The affinity of Spheron-Oxin ® functional groups enables determination of the overall uranium concentration in water containing carbonates up to the concentration level of 10 2 mg L −1. The effect of uranium binding to the polyacrylamide (APA) and agarose diffusive gels (AGE) was also studied. Uranium is probably bound in both gels by a weak interaction with traces of acrylic acid groups in the structure of APA gel and with pyruvic and sulfonic acid groups in the AGE gel. These sorption effects can be eliminated to the negligible level by prolonged deployment of DGT probes or by disassembling probes after the 1–2 days post-sampling period that is sufficient for release of uranium from diffusive gel and its sorption in resin gel.

DISTRIBUTION OF URANIUM IN WATER OF GRESIK COASTAL WATERS

Determination of uranium in water sample at Gresik coastal waters around Gresik industrial area have been carrid out. The purpose of research is to find the distribution of uranium at the coastal where the phosphate industry standing and potencially to contribute uranium pollutant to the waters. The measurement of uranium was pasive of Gamma Spectrometry, and uranium was measured as 234Th (uranium daughters) on 92.80 and 1001.03 keV gamma energies. Sea water sample was taken up by water pump sampler as a vertical mixing. The sample was sampling on the highest tide and lowest ebb, at the east season (March-August) west season (September-February). The concentration of 238U on higher tide of the west season are range between 0.0016-0.0128 Bq/l, while on lowest ebb of the east season are 0,0013-0,0877 Bq/l. There was significantly different (α= 5%) of uranium concentration in water between two seasons (east and west) in tide and ebb respectively. According to Quality Standard from Dirjen BATAN No.293/Dj/VII/1995 (radioactivity on environment), the concentration of 238U in water obtained from coastal around phosphate industry are still lower than that of recomended values (10.000 Bq/l). Keywords: uranium, sea water, coastal of Gresik

THE MEAN CONCENTRATION OF URANIUM IN DRINKING WATER, URINE, AND HAIR OF THE OCCUPATIONALLY UNEXPOSED FINNISH WORKING POPULATION

Uranium concentrations in the household water, urine, and hair of the occupationally unexposed Finnish working population were determined using inductively coupled plasma mass spectrometry (ICP-MS). The age of the randomly selected participants ranged from 18 to 66 y. The mean concentrations of uranium in water, urine, and hair were 1.25 microg L(-1), 0.016 microg L(-1), and 0.216 microg g(-1), respectively. The mean uranium concentration in hair of the Finnish working population was from 3- to 15-fold higher than the values reported in the literature, while the mean uranium concentration in urine was similar to those measured elsewhere in Europe. The observed large variation in the uranium concentrations in hair and urine can be explained by the variation in the uranium concentration in drinking water. Exceptionally high concentrations have been measured in private drilled wells in the granite areas of Southern Finland.

Estimation of uranium and radon concentration in some drinking water samples of Upper Siwaliks, India

Uranium and radon concentration was assessed in water samples taken from hand pumps, natural sources and wells collected from some areas of Upper Siwaliks, Northern India. Fission track registration technique was used to estimate the uranium content of water samples. The uranium concentration in water samples was found to vary from 1.08 +/- 0.03 to 19.68 +/- 0.12 microg l(-1). These values were compared with safe limit values recommended for drinking water. Most of the water samples were found to have uranium concentration below the safe limit of 15 microg l(-1) (WHO, World Health Organization, Guidelines for drinking-water quality (3rd ed.). Geneva, Switzerland: WHO, 2004). The radon estimation in these water samples was made using alpha-scintillometry to study its correlation with uranium. The radon concentration in these samples was found to vary from 0.87 +/- 0.29 to 32.10 +/- 1.79 Bq l(-1). The recorded values of radon concentration were within the recommended safe limit of 4 to 40 Bq l(-1) (UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiations, Sources and effects of ionizing radiation. New York: United Nations, 1993). No direct correlation was found between uranium concentration and radon concentration in water samples belonging to Upper Siwaliks. The values of uranium and radon concentration in water were compared with that from the adjoining areas of Punjab state, India.

Estimation of uranium and radon concentration in some drinking water samples

The concentration of uranium and radon has been assessed in drinking water samples collected from different areas belonging to the upper Siwaliks of Kala Amb, Nahan and Morni Hills of Haryana and Himachal Pradesh states, India. The water samples are taken from hand pumps, natural sources and wells. Fission track registration technique has been used to estimate the uranium content of water samples. The uranium concentration in water samples varies from ( 1.08 ± 0.03 ) to ( 19.68 ± 0.12 ) μ g L - 1 . These values are compared with safe limit values recommended for drinking water. Most of the water samples are found to have uranium concentration below the safe limit of 15 μ g L - 1 [WHO (World Health Organization), 2004. Guidelines for Drinking-water Quality. third ed.]. The radon estimation in these samples has been made using α -scintillometry to study its correlation with uranium. The radon concentration in these samples is found to vary from ( 0.87 ± 0.29 ) to ( 32.10 ± 1.79 ) Bq L - 1 . The recorded values of radon concentration are within the recommended safe limit of 4– 40 Bq L - 1 [UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiations), 1993. Sources and Effects of Ionizing Radiation. United Nations, New York]. No direct correlation is found between uranium concentration and radon concentration in water samples belonging to upper Siwaliks. The values of uranium and radon concentration in water are compared with that from the adjoining areas of Punjab.

Behavior of uranium under conditions of interaction of rocks and ores with subsurface water

The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ≤10−8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO2) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water increases by orders of magnitude and subsurface water is commonly undersaturated with uranium. Uranium absorbed by secondary minerals, particularly by iron hydroxides and leucoxene, is its single stable species under oxidizing conditions. The impact of oxygen-bearing water leads to destruction of uranium ore. This process is realized simultaneously at different hypsometric levels even if the permeability of the medium is variable in both the lateral and vertical directions. As a result, intervals containing uranyl minerals and relics of primary uranium ore are combined in ore-bearing zones with intervals of completely dissolved uranium minerals. A wide halo of elevated uranium contents caused by sorption is always retained at the location of uranium ore entirely destroyed by weathering. Uranium ore commonly finds itself in the aeration zone due to technogenic subsidence of the groundwater table caused by open-pit mining or pumping out of water from underground mines. The capillary and film waters that interact with rocks and ores in this zone are supplemented by free water filtering along fractures when rain falls or snow is thawing. The interaction of uranium ore with capillary water results in oxidation of uraninite, accompanied by loosening of the mineral surface, formation of microfractures, and an increase in solubility with enrichment of capillary water in uranium up to 10−4 mol/l. Secondary U(VI) minerals, first of all, uranyl hydroxides and silicates, replace uraninite, and uranium undergoes local diffusion redistribution with its sorption by secondary minerals of host rocks. The influx of free water facilitates the complete dissolution of primary and secondary uranium minerals, the removal of uranium at the sites of groundwater discharge, and its redeposition under reducing conditions at a greater depth. It is evident that the conditions of the upper hydrodynamic zone and the aeration zone are unfit for long-term insulation of SNF and high-level wastes because, after the failure of containers, the leakage of radionuclides into the environment becomes inevitable.

Release and speciation of uranium in low-ionic-strength groundwaters at an abandoned uranium mine in Val Vedello (Orobic Alp—Italy) by adsorptive cathodic stripping voltammetry

Adsorptive cathodic stripping voltammetry (AdCSV) with HDME and a chloranilic acid ligand was used in the trace analysis of uranyl ions at pH = 2 in low-ionic-strength groundwaters around mining areas. Upon optimization, the limit of detection around 0.10 µg L−1 was found with linearity up to 10 µg L−1. In the abandoned mining area of Val Vedello (Orobic Alps, Italy), measured uranium concentrations in water ranged from 0.3 µg L−1 above the uranium mineralization levels to 145 µg L−1 in groundwaters percolating from mine galleries. Such uranium concentrations are related to natural weathering effects of CO2 and/or hydrogen carbonate ion on uranium mineralizations under oxic conditions. A marked seasonal dependence was then found, in agreement with literature data on a pre-operational survey dating back to 1980–1981. No significant chemical impact of the abandoned mining activity on groundwater quality could be found. Accordingly, no significant increase in contaminants derived from the heat-burn of explosives, such as chloride and nitrate, in groundwaters from mine galleries was found.

Measurements of radon and uranium concentration in water and soil samples from East Anatolian Active Fault Systems (Turkey)

Different water samples collected from over the North and East Anatolian Fault Systems (NAFS and EAFS) were analyzed for radon concentration, effective radium content and radon exhalation rate using the closed-can technique which includes CR-39 passive detectors and also, annual effective dose have been calculated for the water samples. The uranium concentrations in soil samples were also determined by using NaI(Tl) gamma spectroscopic method. The measured maximum values of the effective radium and radon concentrations in the water samples were 270.5 and 3319.3 Bq / m 3 , respectively. However, radon exhalation rate in the water samples varied between 20.2 and 470.0 mBq / m 2 h. The uranium concentrations in soil samples varies between 12.4 ± 1.2 and 138.0 ± 6.1 Bq / kg . The highest annual effective doses obtained for radium and radon are 55.1 and 14.5 μ Sv / y , respectively.