High Uranium Content Research Articles

Harnessing a radiation inducible promoter of Deinococcus radiodurans for enhanced precipitation of uranium

Bioremediation is an attractive option for the treatment of radioactive waste. We provide a proof of principle for augmentation of uranium bioprecipitation using the radiation inducible promoter, Pssb from Deinococcus radiodurans. Recombinant cells of D. radiodurans carrying acid phosphatase gene, phoN under the regulation of Pssb when exposed to 7kGy gamma radiation at two different dose rates of 56.8Gy/min and 4Gy/min, showed 8–9 fold increase in acid phosphatase activity. Highest whole cell PhoN activity was obtained after 2h in post irradiation recovery following 8kGy of high dose rate radiation. Such cells showed faster removal of high concentrations of uranium than recombinant cells expressing PhoN under a radiation non-inducible deinococcal promoter, PgroESL and could precipitate uranium even after continuous exposure to 0.6Gy/min gamma radiation for 10 days. Radiation induced recombinant D. radiodurans cells when lyophilized retained high levels of PhoN activity and precipitated uranium efficiently. These results highlight the importance of using a suitable promoter for removal of radionuclides from solution.

Soil gas radon assessment and development of a radon risk map in Bolsena, Central Italy.

Vulsini Volcanic district in Northern Latium (Central Italy) is characterized by high natural radiation background resulting from the high concentrations of uranium, thorium and potassium in the volcanic products. In order to estimate the radon radiation risk, a series of soil gas radon measurements were carried out in Bolsena, the principal urban settlement in this area NE of Rome. Soil gas radon concentration ranges between 7 and 176 kBq/m3 indicating a large degree of variability in the NORM content and behavior of the parent soil material related in particular to the occurrence of two different lithologies. Soil gas radon mapping confirmed the existence of two different areas: one along the shoreline of the Bolsena lake, characterized by low soil radon level, due to a prevailing alluvial lithology; another close to the Bolsena village with high soil radon level due to the presence of the high radioactive volcanic rocks of the Vulsini volcanic district. Radon risk assessment, based on soil gas radon and permeability data, results in a map where the alluvial area is characterized by a probability to be an area with high Radon Index lower than 20 %, while probabilities higher than 30 % and also above 50 % are found close to the Bolsena village.

Development of a rapid method to determine plutonium in foodstuffs

In this paper a method development for rapid determination of plutonium in food samples after a radiological emergency and its challenges are described. Tests were conducted using sea sediment reference material, fish reference material and spiked samples with high thorium and uranium concentration. After microwave digestion plutonium was separated from the sample matrix using ion-exchange chromatography and determined by inductively coupled plasma mass spectrometry or alpha spectrometry. Interferences during plutonium determinations with the inductively coupled plasma mass spectrometry originated from uranium and were corrected using interference calibration.

Radioactive elements in collisional and within-plate Sodic-Potassic Granitoids: Accumulation levels and metallogenic significance

New data are reported on the content of radioactive elements in the Precambrian Na-K granitoids from the southwestern margin of the Siberian Craton, Aldan and Ukrainian shields, and Kursk-Voronezh Massif. Analytical data on other regions were generalized for comparison. Two global epochs of Na-K granitoid magmatism bearing elevated contents of radioactive elements (U, Th, K) were distinguished in the Early Precambrian (in Ga): Neoarchean (2.8-2.6) and Late Paleoproterozoic (1.9-1.75). Mesoarchean (3.1-2.8 Ga) epoch of Na-K granite formation has been additionally distinguished at the Australian, South African, and Canadian shields. These epochs of granitization provided high maturity of the crust: geochemical differentiation of the oldest continental blocks and their geochemical and metallogenic specialization for trace elements and RAE. In the southern margin of the Siberian Craton, the most intense granite formation occurred in the Late Paleoproterozoic. The extended South Siberian belt of collisional and within-plate Na-K granitoids is characterized by intense influx of RAE and other trace elements in the upper crustal shell. The southwestern margin of the craton (Yenisei Range) was spanned by repeated Late Neoproterozoic Na-K granite formation, with wide development of collisional and within-plate Na-K granites having elevated Th content and [Th]/[U] ratio. The higher RAE concentrations are typical of within-plate Paleo and Neoproterozoic granitoids. The highest uranium content was found in the postcollisional and within-plate Na-K granites and subalkaline leucogranites. Uranium ore concentrations were formed at the riftogenic stages of evolution of these crustal blocks, when within-plate subalkaline acid magmatism and accompanying hydrothermal metamorphism overprinted granitized crystalline massifs, including high-U sedimentary and volcanic complexes. Areas with the most favorable geological-geochemical environments for the formation of uranium mineralization were distinguished in the southern margin of the Siberian Craton and its nearest folded framing.

Radioactivity in the groundwater of a high background radiation area

Natural radioactivity was measured in groundwater samples collected from 37 wells scattered in an inhabited area of high natural background radiation, in a purpose of radiation protection. The study area is adjacent to Aja heights of granitic composition in Hail province, Saudi Arabia. Initial screening for gross α and gross β activities showed levels exceeded the national regulation limits set out for gross α and gross β activities in drinking water. The gross α activity ranged from 0.17 to 5.41 Bq L−1 with an average value of 2.15 Bq L−1, whereas gross β activity ranged from 0.48 to 5.16 Bq L−1, with an average value of 2.60 Bq L−1. The detail analyses indicated that the groundwater of this province is contaminated with uranium and radium (226Ra and 228Ra). The average activity concentrations of 238U, 234U, 226Ra and 228Ra were 0.40, 0.77, 0.29 and 0.46 Bq L−1, respectively. The higher uranium content was found in the samples of granitic aquifers, whereas the higher radium content was found in the samples of sandstone aquifers. Based on the obtained results, mechanism of leaching of the predominant radionuclides has been discussed in detail.

Uranium incorporation into amorphous silica.

High concentrations of uranium are commonly observed in naturally occurring amorphous silica (including opal) deposits, suggesting that incorporation of U into amorphous silica may represent a natural attenuation mechanism and promising strategy for U remediation. However, the stability of uranium in opaline silicates, determined in part by the binding mechanism for U, is an important factor in its long-term fate. U may bind directly to the opaline silicate matrix, or to materials such as iron (hydr)oxides that are subsequently occluded within the opal. Here, we examine the coordination environment of U within opaline silica to elucidate incorporation mechanisms. Precipitates (with and without ferrihydrite inclusions) were synthesized from U-bearing sodium metasilicate solutions, buffered at pH ∼ 5.6. Natural and synthetic solids were analyzed with X-ray absorption spectroscopy and a suite of other techniques. In synthetic amorphous silica, U was coordinated by silicate in a double corner-sharing coordination geometry (Si at ∼ 3.8-3.9 Å) and a small amount of uranyl and silicate in a bidentate, mononuclear (edge-sharing) coordination (Si at ∼ 3.1-3.2 Å, U at ∼ 3.8-3.9 Å). In iron-bearing synthetic solids, U was adsorbed to iron (hydr)oxide, but the coordination environment also contained silicate in both edge-sharing and corner-sharing coordination. Uranium local coordination in synthetic solids is similar to that of natural U-bearing opals that retain U for millions of years. The stability and extent of U incorporation into opaline and amorphous silica represents a long-term repository for U that may provide an alternative strategy for remediation of U contamination.

Environmental hazards and distribution of radioactive black sand along the Rosetta coastal zone in Egypt using airborne spectrometric and remote sensing data

High-resolution airborne gamma ray spectrometry, conducted in 2003, was used to estimate radioactive elements spatial abundance along the Rosetta coastal zone area. It was noticed that both Uranium and Thorium are concentrated in the black sand deposits along the beach. In contrary, Potassium was observed in high level abundance at the cultivated Nile Delta lands due to the accumulated usage of fertilizers. Exposure Rate (ER), Absorbed Dose Rate (ADR) and Annual Effective Dose Rate (AEDR) were calculated to evaluate the radiation background influence in human. Results indicated that the human body in the study sites is subjected to radiation hazards exceeds the accepted limit for long duration exposure. In addition, the areas covered by the highest concentration of Uranium and Thorium show the highest level of radiogenic heat production. Detection the environmental hazards of the radioactive black sands in the study site encouraged this research to monitor the spatial and temporal distribution of these sediments. The Landsat Thematic Mapper images acquired in 1990, 2003 and 2013 were analyzed using remote sensing image processing techniques. Image enhancements, classification and changes detection indicated a positive significant relationship between the patterns of coastline changes and distribution of the radioactive black sand in the study sites. The radioactive black sands are usually concentrated in the eroded areas. Therefore, in 1990 high concentration of the radioactive black sands were observed along the eastern and western flanks of the Rosetta promontory. Distribution of these sediments decreased due to the construction of the protective sea walls. Most of the radioactive black sands are transported toward the east in Abu Khashaba bay under the effect of the longshore currents and toward the west in Alexandria and Abu Quir bay under the action of the seasonal reverse currents.

A multi-instrumental geochemical study of anomalous uranium enrichment in coal

Contents of uranium in coals from Odeř in the northernmost part of the Sokolov Basin, Czech Republic, in the vicinity of the well known St. Joachimsthal uranium ore deposits, reach extremely high values. In the present work, coal samples with contents of uranium ranging from 0.02 to 6 wt.% were studied. The study employing a whole complex of analytical techniques has been aimed at identification of changes in the structure of coal organic matter, which are associated with the high contents of uranium in coal. The study includes proximate and ultimate analyses, multielement analysis by instrumental neutron and photon activation analyses, micropetrographic analysis by optical microscopy, ESEM/EDX analysis of mineral matter, infrared and Raman spectroscopies, solvent extraction followed by gas chromatography with mass spectroscopy (GC/MS), and analytical pyrolysis (Py-GC/MS). The study has confirmed previously proposed explanation of uraniferous mineralization in sedimentary carboniferous substances by the mechanism of reduction and fixation of soluble U(VI) (uranyl, UO22+) species (e.g., humic, carbonate/hydroxo/phosphate complexes) by sedimentary organic matter under diagenetic or hydrothermal conditions, and formation of insoluble U(IV) species as phosphate minerals and uraninite. The process is accompanied with alteration and destruction of the coal organic matter. The changes in the structure of coal organic matter involve dehydrogenation and oxidation mainly in the aliphatic, aromatic and hydroxyl structures, and an increase in aromaticity, content of ether bonds, and the degree of coalification.

Decontamination of gravels contaminated with uranium

Gravel washing equipment and electrokinetic–electrodialytic decontamination equipment were manufactured to decontaminate gravel contaminated with uranium. The removal efficiency according to the gravel size and weight and the removal efficiency according to the lapsed time using the manufactured equipment were investigated through several experiments. The volume of gravel in the high uranium concentration group was about 10%, the rock types of which were quartz, lamprophyre, and schist. The larger the gravel size, the higher the contaminated concentration of gravel. The average uranium (238U) concentration of gravel after the first washing was about 1.45Bq/g, and the average removal efficiency of gravel after the third washing was about 37%. In addition, the removal efficiency of the contaminated gravel was not related to its size. The contaminated concentration of the gravel decreased with an increasing gravel weight. In addition, the removal efficiency of contaminated gravel was not related to its weight. When the electrokinetic–electrodialytic decontamination period of 5days, 10days, 15days, and 20days elapsed, the 238U in the gravel was removed by about 40%, 65%, 72%, and 81%. The more the electrokinetic–electrodialytic decontamination time elapsed, the more the removal efficiency ratio of 238U decreased. Finally, the gravel with a size of less than 10cm was treated by soil washing and electrokinetic decontamination methods with soil, and gravel with size of more than 10cm but less than 20cm was treated by gravel washing and electrokinetic–electrodialytic decontamination methods. Gravel with a size of more than 20cm is treated by a gravel washing method, and gravel contaminated with a high concentration of uranium was treated by crushing and ball mill washing methods.

Seismic mapping and geomechanical analyses of faults within deep hot granites, a workflow for enhanced geothermal system projects

Areas with deep seated radioactive granites are considered targets for enhanced geothermal system (EGS) projects. These areas normally exhibit high heat flow and temperature anomalies related to granitic bodies. High concentrations of uranium within the granites are the most likely cause of the anomalous temperatures. Elevated temperatures are also resulted to high heat flow and thick sedimentary rock cover that includes insulating materials such as coals and gas reservoirs.In this study we investigated the use of 3D seismic amplitudes and attributes to map deep granitic bodies and faults in the Cooper Basin of South Central Australia. We established a workflow for possible geomechanical fluid flow susceptibility analyses for faults that intersect granites. The far field stress tensor must be interpreted through analyses of image logs and formation tests. Our geomechanical analyses models show how this stress tensor affects basement faults interpreted from 3D seismic surveys. Normal stresses, shear stresses, slip tendency, and distance to failure should be modelled for the faults that cut the granites. The optimal orientation of faults that can be possible conduits are then located. We suggest that the optimal injection and production wells should be located at tips of shallow faults that penetrate the granites. We anticipate that short horizontal faults that are located far from other faults will form a more secure fluid conduit. Finally, this study can be a workflow to evaluate the relative merit of future enhanced geothermal system projects.

New insights into the extraction of uranium(VI) by an N,N-dialkylamide

This paper presents the methodology developed in order to thoroughly characterise a solvent extraction system containing high solute concentrations. The chemical system selected is N,N-(2-ethylhexyl)isobutyramide (DEHiBA) diluted in one alkane with increasing concentration of uranium(VI). Combining experiments with theoretical calculations allowed a deeper understanding of the extraction mechanism. A thermodynamic study was performed by the classical van't Hoff method and also by direct calorimetry to provide the enthalpies of extraction and specific heats. Dedicated methods like vapour pressure osmometry and electrospray ionisation mass spectrometry analysis provide information about the stoichiometry of the extracted species. Spectroscopic investigations with ultraviolet–visible and Fourier transform infrared probed the uranium coordination. Finally, a combination of molecular dynamics simulations, and small and wide-angle X-ray scattering experiments investigated the organisation in the organic phase beyond the molecular scale. It was shown that the high concentrations of uranium extracted have no influence on the stoichiometry of the complexes and the coordination of uranium in the inner sphere. The thermodynamic properties related to the extraction process and obtained with a fine consideration of the activity coefficients showed to be the same as those found with trace concentration. However, an unexpected organisation beyond the molecular scale was observed with an important role of nitrates as bridging ligands which could explain some physico-chemical properties. This approach could be applied to other chemical systems (other N,N-dialkylamides or other cations) to identify the origin of the different affinities between ligands and the difference of selectivity between cations.

Performance Study of Some Reverse Osmosis Systems for Removal of Uranium and Total Dissolved Solids in Underground Waters of Punjab State, India

Radionuclides (uranium, thorium, radium, radon gas etc.) are found naturally in air, water, soil and rock. Everyday, we ingest and inhale these radionuclides through the air we breathe and through food and water we take. Out of the internal exposure via ingestion of radionuclides, water contributes the major portion. The natural radioactivity of water is due to the activity transfer from bed rock and soils. In our surveys carried out in the past few years, we have observed high concentrations of uranium and total dissolved solids (TDS) in drinking waters of some southern parts of Punjab State exceeding the safe limits recommended by national and international agencies. The main drinking water source is the underground water procured from different depths. Due to the highly saline taste, disorders in their digestive systems and other ailments, people are installing reverse osmosis (RO) systems in their houses. Some RO systems have been installed on commercial basis. The state government is also in the process of installing community RO systems at the village level. As high values of uranium are also undesired and may pose health hazards due to radioactivity and toxicity of uranium, we have conducted a survey in the field to study the performance of various RO systems for removal of uranium and TDS. Water samples from about forty RO systems from Faridkot, Mansa, Bathinda and Amritsar districts of Punjab State were collected and analyzed. Our results show that some RO systems are able to remove more than 99% of uranium in the underground waters used for drinking purposes. TDS values are also reduced considerably to the desired levels. So RO systems can be used to avoid the risk of unduly health problems posed by high concentrations of uranium and TDS in drinking water.

Activating molecules, ions, and solid particles with acoustic cavitation.

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

GEOCHEMICAL AND MINERALOGICAL CHARACTERIZATION OF NATASH VOLCANICS, SOUTH EASTERN DESERT, EGYPT

The two ring structures of Western Ghurfa and Gaziret Khashm Natash as well as the ring dyke, G.El Ghurfa have extruded through the volcanic flows. The three rings range in composition from volcanicflows, represented by trachybasalt, trachyandesite, normal trachyte and alkaline trachyte and pyroclasticrocks (agglomerates, tuffs, pumice and scoria). The rings are semicircular to circular in outline range from1 km to 0.6 km.The high contents of uranium in the studied rocks are due to the presence of secondary uranium mineralssuch as meta-autunite and kasolite as well as the accessory minerals bearing uranium such as monazite,xenotime, zircon and allanite.The geochemical studies of the volcanic rocks revealed that the rock samples fall in the trachyte,trachyandesite , trachybasalt and basalt fields. These rocks were originated from alkaline magma, anddeveloped in continental basalt environment. The enrichment of the LREEs (182 - 391 ppm) is most due tothe presences of garnet in the source.

English

The metamorphosed sandstones exposures occur in two locations in Wadi Sikait. The exposed rocks in this area are ophiolitic mélange, metamorphosed sandstones, porphrytic granites invaded by post-granite dykes (lamprophyres) and quartz-fluorite veins. The uranium contents measured radiometrically range from 3 to 41.97 ppm, with an average of 12 ppm, while the chemically measured are in the range from 20 to 100 ppm and averaging 50.83 ppm. High uranium contents are mainly attributed to the presence of secondary uranium minerals (uranophane and autonite), accessory minerals (monazite, zircon, allanite and xenotime) and U-bearing minerals (muscovite, biotite, chlorite, iron oxides and clays). P- and D-factors indicate disequilibrium in U-decay due to addition of uranium in these rocks. Since radioactive secular equilibrium of the young age deposits have not yet reached, therefore, the activity ratios (AR) of 230Th/234U in the studied rocks is very small and ranges from 0.43 to 1.3. Radon exhalation rates of the studied rocks were also measured using ‘‘Sealed Can technique” and indicated the presence of subsurface and surface uranium anomaly which confirms the previous results.   Key words: Metamorphosed sandstones, uranium, minerals, Wadi Sikait.

The influence of irrigation and Wuliangsuhai Lake on groundwater quality in eastern Hetao Basin, Inner Mongolia, China

Geochemical and isotopic characterization of groundwater and lake-water samples were combined with water and total dissolved solids balances to evaluate sources of groundwater quality deterioration in eastern Hetao Basin, Inner Mongolia, China. Groundwater quality is poor; 11 of 13 wells exceed drinking-water guidelines for at least one health-based parameter and all wells exceed aesthetic guidelines. The well water is largely derived from Yellow River irrigation water. Notably high uranium concentrations in the Yellow River, relative to world rivers, suggest groundwater uranium and other trace elements may originate in the river-derived irrigation water. Complex hydrostratigraphy and spatial variation in groundwater recharge result in spatially complex groundwater flow and geochemistry. Evapotranspiration of irrigation water causes chloride concentration increases of up to two orders of magnitude in the basin, notably in shallow groundwater around Wuliangsuhai Lake. In addition to evapotranspiration, groundwater quality is affected by mineral precipitation and dissolution, silicate weathering, and redox processes. The lake-water and TDS balances suggest that a small amount of discharge to groundwater (but associated with very high solute concentrations) contributes to groundwater salinization in this region. Increasing salinity in the groundwater and Wuliangsuhai Lake will continue to deteriorate water quality unless irrigation management practices improve.

Ecotoxicity evaluation of an amended soil contaminated with uranium and radium using sensitive plants

As a result of former uranium mining at Urgeiriça (central-northern Portugal), the studied adjacent agriculture soils (Fluvisols) had high total concentration of uranium (~660mg/kg) and high radium-226 activity (~2310Bq/kg). The environmental risk of these soils is also related to the high available concentrations (soluble+exchangeable fraction extracted with ammonium acetate) of uraniumtotal and radium-226, which represent 100% and 20% of their total concentrations, respectively. The objective of this work was to evaluate the effect of different amendments (sheep manure and bone meal) in the toxicity reduction from agricultural soils contaminated with uranium and radium, by bioassays using two sensitive plants (Lactuca sativa L. and Zea mays L.). Pot experiments (microcosm experiments), under controlled conditions, were undertaken during two months of incubation at 70% of the soil water-holding capacity. Bone meal at 40Mg/ha, sheep manure at 70Mg/ha, and two mixtures of bone meal and sheep manure (40Mg/ha+70Mg/ha and 20Mg/ha+70Mg/ha, respectively) were used as amendments. The amendments' application, independently of their type and concentration, reduced drastically the radionuclides concentrations in the soil available fraction and in the soil leachates. Bioassays using the two above plant species, in different matrices (filter test, soil test and hydroponic test), showed that the soil from Urgeiriça did not have any ecotoxic effect from the radionuclides.

Yield and uranium concentration in two lettuce (Lactuca sativa L.) varieties influenced by soil and irrigation water composition, and season growth

The use of contaminated land or irrigation water for agriculture in the neighborhood of mines as well as the transfer of metals from soils to vegetables and to humans through the food chain is a worldwide concern. This study was conducted to compare the effects on lettuce (Lactuca sativa L. varieties Marady and Romana) grown in different seasons (autumn and summer) when exposed to high and low uranium concentrations, both in irrigation water and soils (total and available fraction), near a former uranium mine. Irrigation with uranium contaminated water (0.94 to 1.14mg/L) together with high concentrations of uranium in the soil available fraction (9.2 to 14.5mg/kg) had negative effects on both lettuce varieties, namely on leaf yield reduction (up to 53% and 87% in autumn and summer experiments, respectively) and increase of uranium concentration in the leaves (up to 2.13 and 5.37mg/kgdryweight) and in the roots (up to 4.64 and 28.2mg/kgdryweight) for Marady and Romana varieties, respectively. The effect on lettuce yield was mainly due to the soil salinity (electrical conductivity up to 6.31mS/cm) as a consequence of water irrigation with high electrical conductivity (1.67 to 1.82mS/cm) and low tolerance of lettuce to the soil salinity. The highest concentration of uranium in the Romana variety was also the result of its growth in a dry season when the frequency and amount of water irrigation was great. The consumption of uranium by an adult, teenager and child, from lettuce that concentrate more this element (234μgU/kg fresh weight) was, respectively, 16.7, 17.7 and 24.4% of the tolerable daily limit intake set by the World Health Organization (0.6mgU/kg body weight daily; WHO, 2005). These values suggest that lettuce had low impact on human uranium intake and should not present a concern for Cunha Baixa inhabitant's health assuming that this vegetable is the only food consumed with high uranium concentrations.

Radionuclides in Fracking Wastewater: Managing a ToxicBlend

Naturally occurring radionuclides are widely distributed in the earth’s crust, so it’s no surprise that mineral and hydrocarbon extraction processes, conventional and unconventional alike, often produce some radioactive waste.1 Radioactive drilling waste is a form of TENORM (short for “technologically enhanced naturally occurring radioactive material”)—that is, naturally occurring radioactive material (NORM) that has been concentrated or otherwise made more available for human exposure through anthropogenic means.2 Both the rapidity and the extent of the U.S. natural gas drilling boom have brought heightened scrutiny to the issues of radioactive exposure and waste management. Perhaps nowhere is the question of drilling waste more salient than in Pennsylvania, where gas extraction from the Marcellus Shale using hydraulic fracturing (fracking) made the state the fastest-growing U.S. producer between 2011 and 2012.3 The Marcellus is known to have high uranium content, says U.S. Geological Survey research geologist Mark Engle. He says concentrations of radium-226—a decay product of uranium—can exceed 10,000 picocuries per liter (pCi/L) in the concentrated brine trapped in the shale’s depths. A lined impoundment receives waste at a fracking site in Dimock, Pennsylvania. To date the drilling industry and regulators have considered the risk posed to workers and the public by radioactive waste to be minor. In Pennsylvania, Lisa Kasianowitz, an information specialist with the state Department of Environmental Protection (PADEP), says there is currently nothing to “indicate the public or workers face any health risk from exposure to radiation from these materials.” But given the wide gaps in the data, this is cold comfort to many in the public health community.

Use of Chemical and Isotopic Signatures to Distinguish Between Uranium Mill‐Related and Naturally Occurring Groundwater Constituents

AbstractChemical and isotopic signatures were determined in groundwater samples to aid in distinguishing the source of contamination in three desert arroyos and a buried channel (the swale) near Shiprock, New Mexico. The contamination in the swale and one of the arroyos, Many Devils Wash, was previously attributed to a former uranium mill site because of the similar suite of contaminants (nitrate, selenium, sulfate, and uranium) and the close (0.8 km) proximity. The other two arroyos are far removed from the mill site and could not have received contamination from it. Principal component and cluster analysis indicated similarities in groundwater chemistry among the swale and the three arroyos that contrasted with groundwater chemistry at the disposal cell. Disposal cell groundwater is characterized by high uranium and bicarbonate concentrations, whereas that in remaining study areas is characterized by high sodium and sulfate, but lower uranium concentrations. Mancos Shale forms the bedrock in the region and contains elevated concentrations of the same chemical constituents that appear in the swale and arroyo groundwater. Dissolved sulfate in arroyo groundwater was depleted in sulfur‐34, in contrast to mill‐derived sulfate with more enriched sulfur‐34. Uranium‐234 to uranium‐238 activity ratios (ARs) were near the secular equilibrium value of 1 in mill site groundwater, whereas ARs in all arroyo groundwater samples exceeded 2. Elevated tritium activities present in mill site groundwater (49 to 142 pCi/L) are attributed to the mill being operated during atomic bomb testing in the 1950s and 1960s. The combined chemical and isotopic results indicate that groundwater in Many Devils Wash and the swale was likely derived from the Mancos Shale and not from the milling operation.