High Uranium Content Research Articles

Geochemistry and spectrometric prospection of younger granites and granitic pegmatites bearing uranium mineralization at G. Kab El Rakeb area, Central Eastern Desert, Egypt

The present study deals with the detailed field geology, mineralogy, geochemistry, and spectrometric prospection of rare metals and radioactive minerals associated with granitic pegmatites in the Gabal Um Lassaf- Abu Dob- Um Atelia- Kadabora- Kab El Rakeb area (LDAKK), which are situated in the central Eastern Desert of Egypt. The study area is composed of granodiorites and monzogranites. The latter is dissected by granitic pegmatites with a discriminatory distribution of economically important mineralization (rare-metals and U–Th minerals). The granitic pegmatites display a zoning structure composed of feldspar-rich zones enveloping pockets of mica (mostly muscovite) and all zoning internal quartz core. Microscopically, the monzogranite and granitic pegmatites are composed of potash-feldspar, albite, and quartz with a small amount of biotite and muscovite. The mineralogical investigation of the highly radioactive zones in the granitic pegmatite shows enrichment in kasolite, uranothorite, thorite, xenotime, columbite, zircon, bismuth, and galena. Geochemically, the granitic pegmatites are enriched with high field strength elements (HFSE; Zr, Nb, Th, and U) and ion lithophilic elements (LILE; Rb, and Pb) and depleted in Ba, Sr, and Eu. They are strongly peralkaline to metalumainous except for two samples, which are peraluminous. They are formed by partial melting of metagreywackes at depth. The studied granitic pegmatites could belong to the NYF family (Niobium–Yttrium–Fluorine family) according to the geochemistry of the trace elements. The studied granitic pegmatites show deep negative Eu anomaly and display a strong M-type tetrad effect of rare earth elements. The field spectroscopy measurements showed the localization of the radiometric anomalous associated with the granitic pegmatites, which are intruded in the granitic host rocks. Their eU and eTh contents reached up to 316 and 1367 ppm, respectively. Uranium and thorium occurrences in the investigated granitic pegmatites are related to magmatic (syngenetic) origin with hydrothermal (epigenetic) input. The magmatic mineralization is evidenced by the occurrence of thorite and zircon, whilst the hydrothermal activity is represented by alteration of feldspars and formation of pyrite and iron oxides associated with the radioactive minerals. The high concentrations of uranium and rare metals mineralization in the investigated granitic pegmatites make them a target to exploration and to enlarge the potentiality of the highly mineralized zones.

Influence of climate and weather on the mitigation of radon exposure in two towns of the Western Cape, South Africa

ABSTRACT Globally, exposure to high levels of radon gas is a known health risk. Granite commonly contains high concentrations of uranium and subsequently high exhalation of radon gas. In the Saldanha Bay area of South Africa, granites dominate the underlying geology as well as the surface characteristics of the area. This implies that elevated levels of radon gas may exist in houses in the area. However, a survey of indoor radon concentrations in the town of Vredenburg in the Saldanha Bay area recorded average indoor radon concentrations well below those recommended as threshold levels by international bodies. The average radon concentrations are also significantly below those recorded in Paarl, a town about 100 km south-east of Vredenburg with a similar underlying geology, but different climatological characteristics. Indoor radon concentrations were measured in 34 homes in Vredenburg, and 62 houses in the west side of Paarl, on or near the granite outcrops. Electret ion chambers (E-PERMTM) from Rad-Elec Inc were used to measure indoor radon in the randomly selected houses in each area. For both surveys, the electrets were deployed for periods of between 5 and 20 days. The Paarl survey was conducted between October 2003 and March 2004, while houses in Vredenburg were surveyed during January and February 2019. In this article, researchers develop a theory to explain the lower than predicted indoor radon concentrations, as well as the difference in results obtained from the Vredenburg and Paarl surveys. They attribute these anomalies to the mitigating effect of the prevailing climatological conditions of the Saldanha Bay area and the generally mild climate experienced at both sites. The research postulates that these conditions can significantly reduce the health hazard associated with elevated indoor radon levels.

Estimation of uranium in groundwater and assessment of age-dependent radiation dose in Nalbari district of Assam, India

Uranium concentration has been estimated in 31 groundwater samples collected from the Nalbari district of Assam in pre-monsoon and post-monsoon season. Fourteen other water quality parameters have also been monitored to study their correlation with uranium. The uranium concentration varies from 0.3 to 7.1 µg/L with the mean value of 2.15 µg/L in pre-monsoon and 0.6–10.3 µg/L with the mean value of 2.75 µg/L in the post-monsoon season. The higher concentration of uranium in post-monsoon may be ascribed to the dissolution of uranium from soil sediments in the rainy season. It has been observed that the uranium content in both seasons is far lower than the WHO (2011) permissible limit of 30 µg/L. In both seasons, nitrate, sulphate, and especially phosphate show a positive correlation with uranium, which may be due to different agricultural activities. Agricultural nitrate and phosphate fertilization might be the carrier of uranium in groundwater through dissolution. For all life stage groups, the annual effective dose was appeared to be far below the WHO (2011) prescribed limit of 100 µSv/y. In consideration to adults, the ingestion dose for infants was turned out to be higher. The carcinogenic and non-carcinogenic risk was less than the permissible limits for both children and adults. Both dose value and risk indices were found higher in the post-monsoon season.

Uranium Rhizofiltration by Lactuca sativa, Brassica campestris L., Raphanus sativus L., Oenanthe javanica under Different Hydroponic Conditions

Rhizofiltration experiments were conducted using uranium-contaminated groundwater and lettuce (Lactuca sativa), Chinese cabbage (Brassica campestris L.), radish (Raphanus sativus L.), and buttercup (Oenanthe javanica), which are commonly grown and consumed in South Korea. The results of the rhizofiltration experiments with artificial solutions with different initial uranium concentrations (18, 32, 84, 116, 173, and 263 μg/L) show that the uranium accumulation and bioconcentration factor (BCF) of plant roots increase with increasing uranium concentration in the groundwater. Among the four plants, the uranium concentration in the roots of Raphanus sativus L. is 1215.8 μg/g dry weight, with a maximum BCF value of 2692.7. The BCF value of the artificial solutions with various pH values (pH 3, 5, 7, and 9) is the highest under acidic conditions (pH 3) for all four plants. The uranium BCF values based on different hydroponic conditions range from 170.5 to 11580.3 and the results are comparable with those of other studies using similar methods; the highest BCF value was determined for Brassica campestris L. at pH 3. The BCF values of Raphanus sativus L. after the rhizofiltration experiments with genuine groundwater contaminated with uranium are the highest among the four species; that is, 1684.7 and 1700.1 in Oesam-dong and Bugokdong groundwater samples with uranium concentrations of 83 and 173 μg/L, respectively. The results of the scanning electron microscope/electron dispersive X-ray spectroscope analyses show that uranium in contaminated groundwater is adsorbed as a solid phase on the root surface. These results demonstrate that Raphanus sativus L. has a high tolerance to high concentrations of uranium and low pH conditions and a remarkable potential for uranium accumulation.

Exploration for concealed fracture controlled uranium mineralization: A case from Shivaramapuram-Nutankalva tract in basement granitoids, south of Cuddapah basin, Andhra Pradesh, India

The application of hydro geochemical exploration for sub-surface uranium mineralization is becoming significant due to the geochemical properties of uranium. The oxygen in natural water enhances the mobility of uranium by the complexing action of carbonates and bicarbonates with oxidized uranyl ions. The uranium and its decay products (i.e., radium group) can be used as good tracers for pinpointing uranium mineralization.The basement complex in the south of Cuddapah basin comprises granite, gneiss-migmatites and patches of greenstone belts. There are different generation of fractures and mafic dykes trending E–W, NS, NW-SE and NE–SW directions. The NNE–SSW to NE–SW trending fractures are youngest and often show higher uranium values in water along the same trend indicating possible mineralization. The fractures are often intruded by younger basic intrusive rocks and quartz reefs which often show high uranium content. Several NE–SW to NNE–SSW trending fracture zones with uranium mineralization are observed in the areas around Shivaramapuram-Nutankalva, Kamaguttapalle and T. Sundupalle villages. These sympathetic fracture zones are important for further sub-surface exploration.The present focus is given on a NE-SW fracture zone along Sivaramapuram–Nutanakalva tract extends over a strike length of ~15 km with a plan width of ~1 to 1.5 km. The tract is mostly soil covered and rock outcrops are scanty. Radioactive anomalies are located at small outcrops in fractured basic dyke, fractured and altered granite, deformed quartz vein, sludge samples collected from private village drilling sites, Pincha river channel sands and soils (U3O8 values up to 0.19% (β/γ); n = 44;). Hydrogeochemical exploration along this fracture zone has indicated anomalous concentration of uranium in water samples ranging from 100 to 19,434 ppb U (n = 110). Selective borewells have been monitored for 8 months to check the seasonal variation. The data remain persistent and indicated encouraging outcome. This NE–SW fracture zone has affected the Nagari quartzite of Cuddapah Supergroup, thus indicate Post Nallamalai Mesoproterozoic Grenville orogeny, which is metallogenically favourable epoch for fracture controlled uranium mineralization.The surface anomalies vis-a-vis the hydro uranium anomalies and suitable geochemical condition along the NE-SW trending fracture make this zone a potential target for further sub-surface exploration.

Underground production of 81Kr detected in subsurface fluids

Radiokrypton dating using the long-lived natural isotope 81Kr has been developed for determining the age of ancient groundwater. 81Kr is attractive for this purpose because it is generally thought to be produced solely in the upper atmosphere. Its 229,000-year half-life, a spatially homogeneous distribution in the atmosphere, and the absence of anthropogenic sources makes it an ideal tracer to determine ages up to ∼1.3 million years. As a noble gas, it is inert and thus not subject to interfering geochemical reactions that may alter the age information. We sought to date groundwater samples collected from deep (0.6–1.9 km) rock fractures in the Kaapvaal Craton, South Africa. Previous studies using other dating methods have estimated groundwater ages at these sites in the 1–100 million year range. Surprisingly, three of the four samples collected from flowing boreholes in gold and diamond mines showed 81Kr isotopic abundances at 2–5 times the atmospheric value. This is the first time that underground production of 81Kr has been detected, indicating that 81Kr can be generated underground in measurable quantities in contrast to the long-held paradigm that such production is insignificant in natural rocks. A radionuclide production and release model is proposed in order to quantify the importance of different factors that affect the concentrations of 81Kr in the groundwater. It is not only the high effective uranium content of the rock but also a higher 81Kr fission yield than previously anticipated that are likely causing the elevated 81Kr values in this case. In less extreme environments with average crustal composition (i.e. moderate U concentration), however, we anticipate that the underground production minimally affects groundwater 81Kr dating as demonstrated.

Preparation for reactor tests of uranium-zirconium carbonitride fuel

Uranium-zirconium carbonitride based fuel (CNF) is a consequential modification of UN retaining almost all the advantages of UN. This fuel boasts rather high uranium content and high heat conductivity. Uranium-zirconium carbonitride fuel is safer due to its higher tolerance (inertia) to accident processes development. Thanks to its properties, the CNF is an attractive candidate material for using in reactors of various types. The main drawback of UZr(CN) is insufficient amount of data regarding its performance and behavior under irradiation, especially at high burn-ups. To address this problem, preparations are currently underway to perform a reactor experiment with the goal to study the properties of the CNF after reaching ≈ 7% burn-up. The parameters of the reactor experiment are as follows: cladding temperature not exceeding 800 K, power density not exceeding 750 W/cm3. For the purposes of reactor testing of the CNF pellets at high burn-up, an experimental capsule installed into the irradiating device has been developed. To verify the choice of designs of both the experimental capsule and the irradiating device thermophysical calculations were made and a programme of pre-irradiation experiments was completed. This paper elaborates on the results of the calculations demonstrating that the reactor tests fit the set goals and objectives.

Uranium Anomalies in Recent Sediments of Lakes from the Northern Part of the Murmansk Region, Arctic

Extremely high uranium concentrations (>100 times average crustal content) are established in the recent sediments of small lakes of the northern Murmansk region. It is substantiated that the high uranium concentrations in the sediments of the lakes of the northern Murmansk region were mainly controlled by natural uranium migration from magmatic and metamorphic rocks bearing uranium mineralization (Litsa geological district). The sediments of the studied lakes display a tight correlation of uranium with Mo and rare earth elements usually accompanying uranium in parental rocks. The main chemical fractions of uranium in the lake sediments are revealed. It is shown that organic matter significantly affects the accumulation of this element in the lake sediments.

Radiological and environmental studies on the metamorphosed sandstones at Wadi Sikait area, southeastern desert, Egypt

Wadi Sikait area lies in the southern part of the Eastern Desert of Egypt along the upper stream of Wadi.Sikait. The exposed rock units in Wadi Sikait area are ophiolitic mélange roccks, metamorphosed sandstones, and porphyritic granites, lamprophyre dykes, in addition to fluorite and quartz veins. The activity concentrations of various radionuclides are measured by NaI-Tl activated detector and the radioactive mineralization were determined by Alpha track technique using CR-39 films. Radiometric investigations indicate that 238U activity concentrations range between 37.2 and 520.4 with average 148.8 BqKg−1, 232Th activity concentrations vary between 8.08 and 366.99 BqKg−1 with 76.75 BqKg−1 as an average. The studied metamorphosed sandstones have higher values relative the world concentration levels. High uranium content of the metamorphosed sandstone is attributed to presence radioactive minerals like uranophane and autonite, in addition to accessory minerals like allanite, zircon and monazite. Other U-bearing minerals are also recorded as biotite, muscovite, iron oxides and clays. Absorbed Dose Rate (D), annual effective dose equivalent (AEDE), radium equivalent activity (Raeq), external (Hex) and internal (Hin) hazard index, in addition to activity gamma index (Iγ) caused by gamma emitting natural radionuclide are determined from the obtained values of 226Ra, 232Th and 40K. Fairly, many of the studied metamorphosed sandstone do not satisfy the universal standards.

INDOOR RADON MEASUREMENTS FOR THE SOUTH AFRICAN WEST COAST PENINSULA.

Granite commonly contains high concentrations of uranium, with consequent high exhalation of radon. The geology of the West Coast peninsula of South Africa is dominated by granite, and a recent article predicted potentially high indoor radon concentrations in this region's two largest towns, Vredenburg and Saldanha. This research aimed to measure indoor radon levels in these towns. Measurements were first done for a minimum of 3d during warmer months, with houses typically being more ventilated. Thirty-four homes in Vredenburg and 27 in Saldanha were measured, and the average indoor radon determined to be 40 and 58Bqm-3, respectively. The measurements were then repeated during the colder months, and an increase in average radon concentration of 173Bqm-3 for Saldanha and 153Bqm-3 for Vredenburg was found. The granite geology and lifestyle of occupants during the colder months seem to contribute towards elevated levels of indoor radon concentrations.

Assessment of geothermal potential of parts of Sokoto Basin, Northwest Nigeria using aero-radiometric data

This investigation deals with the assessment of aero-radiometric data of parts of the Sokoto Basin, Northwest Nigeria for the prospect of geothermal energy. The study area lies within the longitude of 4° 30′–6° 00′ East and the latitudes 11° 00′–13° 30′ North covering an estimated total area of 45,375 km2. Fifteen aero-radiometric data sheets used for this investigation were processed, analyzed and interpreted qualitatively and quantitatively. The data were qualitatively interpreted using the blending method in Grid and Image Geosoft extension of Oasis Montaj software. Hence, the concentrations of Potassium, Thorium, and Uranium maps were produced. Quantitively, the rock type in each area was identified while processing the average element in each rock to estimate radiogenic heat production values. The concentrations of Potassium, Thorium and Uranium revealed results of 0.12–2.34%, 4.0–21.6 ppm and 0.6–5.6 ppm, respectively. The radiogenic heat production values vary between 0.95 and 3.63 μW/m3, with an average of 1.93 μW/m3. Consequently, the overall assessments show that the study area possesses moderately high contents of Potassium, Thorium and Uranium. The results of radiogenic heat production also indicated a favourable prospect for geothermal energy around Argungu, Wasagu and Zuru areas. Therefore, exploring these areas for the purpose of geothermal energy would augment power generation in Nigeria.

Site-specific concentration of uranium in urine of workers of the hydrometallurgical plant of Stepnogorsk mining and chemical combine.

Radiation monitoring is an important radiation safety measure implemented at the hydrometallurgical plant of the Stepnogorsk mining and chemical combine (HMP SMCC, Republic of Kazakhstan). Follow-up of the workers and their regular medical examinations has laid the basis to create a cohort with the potential to be used in radiation epidemiology. The aim of current pilot study was to analyze the dose forming factors for workers of HMP SMCC. For this, bioassays samples collected from 54 workers employed at eight HMP workshops were measured using the "Agilent 7800 ICP-MS" mass spectrometer. Three years later, measurements were repeated for four workers with the highest concentrations of uranium in urine. The results of site-specific measurements of dose rates, long-lived alpha-particle activity concentrations and equivalent equilibrium volume activity of radon were derived from the archive of the HMP SMCC Service of Radiation and Toxic Safety and analyzed to fully evaluate the radiation situation at those workplaces. Maximum urine uranium concentrations were measured for workers at the extraction workshop and mechanical repair shop (up to 26.7µg/L and 14.6µg/L, respectively). Urinary uranium from workers employed at other sites was mainly (for about 72% of the samples) in the range of values that may occur in natural conditions (< 0.4µg/L). A wide individual variability in uranium concentration in urine samples (from 60% to 200% of CV) was found. A linear dependence of cumulative effective dose on work experience was found with a slope of 7.5mSv per year. This slope did not depend on working place. For the investigated workers, cumulative effective doses of workers were found in the range of low (< 100mSv) and medium doses (100-500mSv). It is concluded that the newly created cohort of HMP SMCC workers has the potential to improve the knowledge on health effects from low- and medium doses of ionizing radiation.

An investigation on the efficiency of low-cost adsorbents in removing uranium from water samples

The groundwater samples were found to be contaminated with high concentrations of uranium (U) in Punjab state as well as in few other locations of India. U being chemically toxic can deteriorate health when ingested. Hence, there is a need to remove U from contaminated water using an efficient, cheap and user friendly method. A study was initiated to investigate the efficiency of low-cost adsorbents in removing U from water. Seven adsorbents were screened for U removal efficiency, among which fly ash (FA) and tea waste (TW) were found to have better removal efficiency. Solid–liquid contact time and solution pH were optimized to establish conditions for better U removal efficiency. The U adsorption on FA and TW followed pseudo-second-order kinetics with rate constant values 4.63 g/mg/min and 15.63 g/mg/min, respectively. FA and TW had the highest U removal capability at pH 6 and pH 4, respectively. The U sorption data were fitted with Freundlich and Dubinin–Radushkevich isotherm models. The U adsorption on FA and TW is found to be a physical process with mean free energy (E) values less than 8 kJ/mol. Theoretically calculated maximum adsorption capacity values indicate that FA is a better adsorbent as compared to TW, which has been further confirmed experimentally. The U adsorption on both the adsorbents has interference from Ca2+ and no interference from Fe3+ at tested U concentrations. It is also found that FA and TW are effective in decontaminating U from spiked real groundwater samples to below the WHO (Guidelines for drinking water quality, 4th ed, vol 1, World Health Organization, Geneva, 2011) limit.

U-Th dating of lake sediments: Lessons from the 700 ka sediment record of Lake Junín, Peru

Deep sediment cores from long-lived lake basins are fundamental records of paleoenvironmental history, but the power of these reconstructions has been often limited by poor age control. Uranium-thorium (U-Th) dating has the potential to fill a gap in current geochronological tools available for such sediment archives. We present our systematic approach to U-Th date carbonate-rich sediments from the ∼100 m drill core from Lake Junín, Peru. The results form the foundation of an age-depth model spanning ∼700 kyrs. High uranium concentrations (0.3–4 ppm) of these sediments allow us to date smaller amounts of material, giving us the opportunity to improve sample selection by avoiding detrital contamination, the greatest factor limiting the success of previous U-Th dating efforts in other lake basins. Despite this advantage, the dates from 174 analyses on 55 bulk carbonate samples reveal significant scatter that cannot be resolved with traditional isochrons, suggesting that at least some of the sediments have not remained closed systems. To understand the source of noise in the geochronological data, we first apply threshold criteria that screen samples by their U/Th ratio, reproducibility, and δ234Uinitial value. We then compare these results with facies types, trace element concentrations, carbonate and total organic carbon content, color reflectance, mineralogy, and ostracode shell color to investigate the causes of open system behavior. Alongside simulations of the isotopic evolution of our samples, we find that the greatest impediment to U-Th dating of these sediments is not detrital contamination, but rather post-depositional remobilization of uranium. Examining U-Th data in these contexts, we identify samples that have likely experienced the least amount of alteration, and use dates from those samples as constraints for the age-depth model. Our work has several lessons for future attempts to U-Th date lake sediments, namely that geologic context is equally as important as the accuracy and precision of analytical measurements. In addition, we caution that significant geologic scatter may remain undetected if not for labor intensive tests of reproducibility achieved through replication. As a result of this work, the deep sediment core from Lake Junín is the only continuous record in the tropical Andes spanning multiple glacial cycles that is constrained entirely by independent radiometric dates.

Evaluation of mtr cluster expression in Shewanella RCRI7 during uranium removal.

In recent years, bioremediation is considered as an efficient method to remove the pollutants from the industrial wastewater. In this study, quantitative gene expressions (Real-time RT-PCR) of mtr gene cluster (mtrA, mtrB, mtrC, mtrD, mtrE, mtrF and omcA) in five different uranium concentrations (0.1, 0.25, 0.5, 1 and 2mM) were performed with ICP and microscopic live cell counting analysis under anaerobic condition, by Shewanella RCRI7 as a native bacterium. The results indicated that the amount of uranium removal and live-cell counting were decreased in the higher uranium concentrations (1 and 2mM), due to the uranium toxicity, suggesting 0.5mM as the optimum uranium concentration for Shewanella RCRI7 resistance. The expression of mtrCED and omcA genes presented increasing trend in the lower uranium concentrations (0.1, 0.25 and 0.5mM) and a decreasing trend in 1 and 2mM, while mtrABF, presented an inverse pattern, proving the alternative role of mtrF for mtrC and omcA, as the substantial multiheme cytochromes in Extracellular Electron Transfer (EET) pathway. These data are a proof of these gene vital roles in the EET pathway, proposing them for genetic engineering toward EET optimization, as the certain pathway in heavy metal bioremediation process.

УРАН И ТОРИЙ В АЭРОЗОЛЬНЫХ ВЫПАДЕНИЯХ Г. НОВОСИБИРСКА И ЕГО ОКРЕСТНОСТЕЙ (ЗАПАДНАЯ СИБИРЬ)

Актуальность исследования обусловлена необходимостью развития геоэкологических подходов к оценке качества воздуха урбанизированных территорий и выявления вклада выбросов отдельных промышленных источников в общее техногенное загрязнение городского воздуха. Цель: определить техногенную аэрозольную нагрузку и аэрозольное выпадение Th и U в окрестностях пяти крупных промышленных предприятий г. Новосибирска. Объекты: пылеаэрозольные частицы, накопленные в снеговом покрове окрестностей ТЭЦ-2, ТЭЦ-3, ТЭЦ-5, Новосибирского оловокомбината и Новосибирского завода химических концентратов в течение зимнего периода. Техногенная радиоактивная составляющая в аэрозолях г. Новосибирска и его окрестностей ранее в открытой печати подробно не рассматривалась. Методы: отбор крупнообъемных проб снегового покрова (до 400 дм3) для выделения путем фильтрования достаточной для анализов навески твердых взвесей из талого снега; определение плотности среднесуточного выпадения аэрозолей (среднесуточной аэрозольной нагрузки) путем расчетов через отношение массы твердых взвесей, полученных из проб талого снега, к площади отбора и количеству суток существования снегового покрова (со дня формирования снегового покрова до отбора пробы); определение содержания сажи в аэрозолях путем озоления при 550  С, определение содержания Th и U рентгенофлуоресцентным методом на синхротронном излучении. Результаты. На основе данных плотности среднесуточного выпадения аэрозолей в пределах основных ореолов выбросов промышленных предприятий г. Новосибирска проведена оценка загрязнения воздуха городской среды. Определено содержание в аэрозолях Th и U и плотность их выпадения на поверхность земли вместе с аэрозолями. Наиболее высокое содержание урана установлено в аэрозолях, отобранных в пределах ореола выбросов Новосибирского завода химконцентратов. Выявлены особенности поступления Th и U с выбросами ТЭЦ при сжигании бурого и каменного углей.

Effect of Deposit on the Evaporation Rate of Adhered Salt in Uranium Dendrite

Electrorefining is a key step in pyroprocessing. The solid cathode processing is necessary to separate the salt from the cathode of the electrorefiner since the uranium deposit in a solid cathode contains electrolyte salt. Moreover, it is very important to increase the throughput of the salt separation system due to the high uranium content of the spent nuclear fuel and high salt fraction of uranium dendrites. Therefore, in this study, the effect of deposit on the evaporation of the adhered salt in a uranium deposit was investigated by using the samples of salt in the uranium deposit and salt in the deposit of the surrogate material for the effective separation of the salt. It was found that the salt evaporation rate is dependent on the deposit type and bulk density in the crucible. Additionally, the evaporation rate was found to be lower when the deposit structure is complex; the rate also decreases as the bulk density of the deposit is increased owing to the retardation of the salt vapour transport process. It was concluded that the mass transfer of the salt vapour is an important parameter for the achievement of a high throughput performance in the salt distillation process.

Bioremediation of water contaminated with uranium using Penicillium piscarium.

Penicillium piscarium can be indicated as promising in the treatment of sites contaminated with uranium. Thus, this research aimed to analyze the P. piscarium dead biomass in uranium biosorption. This fungus was previously isolated from a highly contaminated uranium mine located in Brazil. Biosorption tests were carried out at pH 3.5 and 5.5 in solutions contaminated with concentrations of 1 to 100 mg/L of uranium nitrate. Our results showed that the dead biomass of P. piscarium was able to remove between 93.2 and 97.5% uranium from solutions at pH 3.5, at the end of the experiment, the pH of the solution increased to values above 5.6. Regarding the experiments carried out in solutions with pH 5.5, the dead biomass of the fungus was also able to remove between 38 and 92% uranium from the solution, at the end of the experiment, the pH of the solution increased to levels above 6.5. The analysis of electron microscopy, Energy-dispersive spectroscopy, and X-ray fluorescence demonstrated the high concentration of uranium precipitated on the surface of the fungal biomass. These results were impressive and demonstrate that the dead biomass of P. piscarium can be an important alternative to conventional processes for treating water contaminated with heavy metals, and we hope that these ecofriendly, inexpensive, and effective technologies be encouraged for the safe discharge of water from industrial activities.

Assessment of Household and Outdoor Air Pollution Exposure Link to Urinary Metals Content in Pregnant Women

We aimed to estimate the association of urinary metal content with the exposure to hazardous household factors and ambient air pollution in pregnant women. We analyzed urine samples of 143 women enrolled at delivery and assessed household exposure by questionnaire. Air pollution estimates were based on monitoring stations and satellite-based models. Complaints about noise, rubbish, and sewage in the neighborhood were associated with higher uranium concentrations (prevalence ratio (PR) = 1.42, 1.46, and 1.18, respectively). Complaints about noise were more frequent in women with higher cobalt, nickel, molybdenum, cadmium, and vanadium urine concentrations (PRs = 2.42–9.43), and complaints about smell in women with higher cobalt and strontium (PRs = 2.55–6.27). Exposure to nitrogen oxides was associated with higher concentrations of nickel, aluminum, lead, and chromium in urine (PRs = 1.80–5.85). Women exposed to elevated levels of particulate matter were more likely to have higher concentrations of cobalt, nickel, thallium, lead, iron, strontium, barium, silver, and chromium (PRs = 1.97–13.64). Exposure to high levels of sulfur dioxide was positively associated with cobalt and nickel (PR = 1.98 and 1.88, respectively). The current analysis suggests the possibility of a related simultaneous exposure to multiple pollutants. Further studies are warranted to corroborate the findings and reveal the multiple exposure effect on human health.

Groundwater characterization and monitoring at a complex industrial waste site using electrical resistivity imaging

A contaminated industrial waste site in Washington State (USA) containing buried, metallic-waste storage tanks, pipes, and wells, was evaluated to determine the feasibility of monitoring groundwater remediation activities associated with an underlying perched aquifer system using electrical resistivity tomography. The perched aquifer, located ~65 m below ground surface and ~10 m above the regional water table, contains high concentrations of nitrate, uranium, and other contaminants of concern from past tank leaks and intentional releases of wastes to surface disposal sites. The extent of the perched water aquifer is not well known, and the effectiveness of groundwater extraction for contaminant removal is uncertain, so supplemental characterization and monitoring technologies are being evaluated. Numerical simulations of subsurface flow and contaminant transport were performed with a highly resolved model of the hydrogeologic system and waste site infrastructure, and these simulations were used as the physical basis for electrical resistivity tomography modeling. The modeling explicitly accounted for metallic infrastructure at the site. The effectiveness of using surface electrodes versus surface and horizontal subsurface electrodes, for imaging groundwater extraction from the perched water aquifer, was investigated. Although directional drilling is a mature technology, its use for electrode emplacement in the deep subsurface under a complex industrial waste site via horizontal wells has not yet been demonstrated. Results from this study indicate that using horizontal subsurface electrode arrays could significantly improve the ability of electrical resistivity tomography to image deep subsurface features and monitor remediation activities under complex industrial waste sites.