Total Uranium Concentrations Research Articles

Geographic and dietary differences of urinary uranium levels in the Strong Heart Family Study.

American Indian (AI) communities are affected by uranium exposure from abandoned mines and naturally contaminated drinking water. Few studies have evaluated geographical differences across AI communities and the role of dietary exposures. We evaluated differences in urinary uranium levels by diet and geographical area among AI participants from the Northern Plains, the Southern Plains, and the Southwest enrolled in the Strong Heart Family Study (SHFS). We used food frequency questionnaires to determine dietary sources related to urinary uranium levels for 1,682 SHFS participants in 2001-2003. We calculated adjusted geometric mean ratios (GMRs) of urinary uranium for an interquartile range (IQR) increase in self-reported food group consumption accounting for family clustering and adjusting for sociodemographic variables and other food groups. We determined the percentage of variability in urinary uranium explained by diet. Median (IQR) urinary uranium levels were 0.027 (0.012, 0.057) μg/g creatinine. Urinary uranium levels were higher in Arizona (median 0.039 μg/g) and North Dakota and South Dakota (median 0.038 μg/g) and lower in Oklahoma (median 0.019 μg/g). The adjusted percent increase (95% confidence interval) of urinary uranium levels per IQR increase in reported food intake was 20% (5%, 36%) for organ meat, 11% (1%, 23%) for cereals, and 14% (1%, 29%) for alcoholic drinks. In analyses stratified by study center, the association with organ meat was specific to North Dakota and South Dakota participants. An IQR increase in consumption of fries and chips was inversely associated with urinary uranium levels -11% (-19%, -3%). Overall, we estimated that self-reported dietary exposures explained 1.71% of variability in urine uranium levels. Our paper provides a novel assessment of self-reported food intake and urinary uranium levels in a cohort of American Indian participants. We identify foods (organ meat, cereals, and alcohol) positively associated with urinary uranium levels, find that organ meat consumption is only associated with urine uranium in North Dakota and South Dakota, and estimate that diet explains relatively little variation in total urinary uranium concentrations. Our findings contribute meaningful data toward a more comprehensive estimation of uranium exposure among Native American communities and support the need for high-quality assessments of water and dust uranium exposures in SHFS communities.

Radioactivity of Technosols on thermal power station ash disposal sites: Assessment of potential radiological human‐health risk

AbstractSoil radioactivity is a poorly recognized form of land degradation; however, there are regions all around the world where it can be dangerous to the environment and human health. The aim of the study was to analyze the radioactivity of Technosols developed on thermal power station (TPS) ash disposal sites. Total concentration of uranium (U), thorium (Th), and cesium (Cs), as well as the radioactivity of select radionuclides in Technosols were determined to recognize the level of radioactivity and to assess the potential radiological health risk. Total U, Th and Cs concentrations in Technosols were in ranges 1.5 to 11.3, 4 to 22.9, and 0.2 to 21.3 mg·kg−1, respectively. The radioisotope activities in Technosols (in Bq·kg−1) were in the 1.6–25.5 (137Cs); 29.2–1265 (40K); 26.2–99.9 (228Th); 27.9–100 (228Ra); 20.5–134. (226Ra); 32.8–177 (210Pb); 23.9–144 (238U); 1.2–7.0 (235U) ranges. The activity concentrations were slightly higher than the activities of non‐contaminated soils. Technosols developed from bituminous coal ash had higher 40K, 228Th, and 228Ra activity concentrations than soils developed from lignite ash. Artificial 137Cs occurred in surface horizons of Technosols due to fall of atmospheric dust enriched in 137Cs. Annual effective dose (AED) in Technosols amounted 0.07–0.16 mSv·a−1 and was somewhat higher than the global and Polish average (0.06 and 0.07 mSv·a−1, respectively) for outdoor external terrestrial radiation. The radioactivity of the investigated Technosols is slightly above the average radioactivity of native soils. The radiological human‐health risk related to the analyzed soils is low.

Preterm Birth and Metal Mixture Exposure among Pregnant Women from the Navajo Birth Cohort Study.

Preterm birth (PTB), defined as birth before 37 wk gestation, is associated with hypertension, diabetes, inadequate prenatal care, unemployment or poverty, and metal exposure. Indigenous individuals are more likely to have maternal risk factors associated with PTB compared with other populations in the United States; however, the role of environmental metals on PTB among pregnant Indigenous women remains uncertain. Previous research identified associations between PTB and individual metals, but there is limited investigation on metal mixtures and this birth outcome. We used a mixtures analysis framework to investigate the association between metal mixtures and PTB among pregnant Indigenous women from the Navajo Birth Cohort Study (NBCS). Maternal urine and blood samples were collected at the time of study enrollment and analyzed for metals by inductively coupled plasma dynamic reaction cell mass spectrometry. Bayesian Profile Regression was used to identify subgroups (clusters) of individuals with similar patterns of coexposure and to model association with PTB. Results indicated six subgroups of maternal participants with distinct exposure profiles, including one group with low exposure to all metals and one group with total arsenic, cadmium, lead, and uranium concentrations exceeding representative concentrations calculated from the National Health and Nutrition Examination Survey (NHANES). Compared with the reference group (i.e., the lowest exposure subgroup), the subgroup with the highest overall exposure had a relative risk of PTB of 2.9 times (95% credible interval: 1.1, 6.1). Exposures in this subgroup were also higher overall than NHANES median values for women 14-45 years of age. Given the wide range of exposures and elevated PTB risk for the most exposed subgroups in a relatively small study, follow-up investigation is recommended to evaluate associations between metal mixture profiles and other birth outcomes and to test hypothesized mechanisms of action for PTB and oxidative stress caused by environmental metals. https://doi.org/10.1289/EHP10361.

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.

Sediment spiking and equilibration procedures to achieve partitioning of uranium similar to contamination in tropical wetlands near a mine site

The derivation of sediment quality guideline values (SQGVs) presents significant challenges. Arguably the most important challenge is to conduct toxicity tests using contaminated sediments with physico-chemistry that represents real-world scenarios. We used a novel metal spiking method for an experiment that ultimately aims to derive a uranium SQGV. Two pilot studies were conducted to inform the final spiking design, i.e. percolating a uranyl sulfate solution through natural wetland sediments. An initial pilot study that used extended mixing equilibration phases produced hardened sediments not representative of natural sediments. A subsequent percolation method produced sediment with similar texture to natural sediment and was used as the method for spiking the sediments. The range of total recoverable uranium (TR-U) concentrations achieved was 8–3200 mg/kg. This reflected the concentrations found in natural wetlands and water management ponds found on a uranium mine site and was above natural levels. Dilute-acid extractable uranium (AE-U) concentrations were >80% of total concentrations, indicating that much of the uranium in the spiked sediment was labile and potentially bioavailable. The portion of TR-U extractable as AE-U was similar at the start and end of the 4.5-month field-deployment. Porewater uranium (PW–U) analyses indicated that partition coefficients (Kd) were 2000–20,000 L/kg, and PW-U was greater in post- than pre-field-deployed samples when TR-U was ≤1500 mg/kg, indicating the binding became weaker during the field-deployment period. At higher spiked-U concentrations, the PW-U was lower post-field-deployment. Comparing the physico-chemical data of the spiked sediments with environmental monitoring data from sediments in the vicinity of a uranium mining operation indicated that they were representative of sediments contaminated by mining and that the U-spiked sediments had a clear U concentration gradient. This confirmed the suitability of the spiking procedure for preparing sediments that were suitable for deriving a SQGV for uranium.

Physical-chemical characterization of uranium containing sediments

The presented paper is intended to study the chemical behaviour of combined geogenicanthropogenic uranium content in specific stream sediments. The sampling points have been chosen with respect to the natural conditions in the locality of groundwater outflow from a former uranium mine adit in Považský Inovec mountain range, near Kálnica village. Besides the total uranium determination and physical-chemical characterization of the relevant water- and sediment samples we carried out modified Tessier type sequential fractionation extractions of natural- and artificially contaminated sediment samples after time dependent agitation in air and in the atmosphere of argon. The obtained results have been compared with those fulfilled with montmorillonite K-10. The total uranium concentrations of the relevant groundwater samples as well as of stream sediments have been determined by ICP-MS using HP 4500. The determinations of uranium in extracts have been accomplished according STN757614, utilizing arsenazo III as a selective complex forming reagent for spectrophotometric determination of uranyl-ions at 650 nm. The total uranium concentration of the groundwater outflow and in the sediment taken in its immediate vicinity has been 31.75±0.35 μg dm-3 and 38.0±2.7 μg g-1 respectively. Unlike montmorillonit K-10, in which the carbonate-bound fraction of uranium after 1 week aeration and agitation in argon atmosphere represents 22.8% and 18.6% respectively, uranium in investigated sediments has been present predominantly in carbonate-bound fraction-reaching under similar conditions 38.6% and 26.6%, respectively.

Surveillance of Depleted Uranium-exposed Gulf War Veterans: More Evidence for Bone Effects.

Gulf War I veterans who were victims of depleted uranium (DU) "friendly-fire" incidents have undergone longitudinal health surveillance since 1994. During the spring of 2019, 36 members of the cohort were evaluated with a monitoring protocol including exposure assessment for total and isotopic uranium concentrations in urine and a comprehensive review of health outcomes, including measures of bone metabolism and bone mineral density (BMD) determination. Elevated urine U concentrations were observed in cohort members with retained depleted uranium (DU) shrapnel fragments. In addition, a measure of bone resorption, N-telopeptide, showed a statistically significant increase in those in the high DU subgroup, a finding consistent with a statistically significant decrease in bone mass also observed in this high DU subgroup compared to the low DU subgroup. After more than 25 y since first exposure to DU, an aging cohort of military veterans continues to show few U-related health effects in known target organs of U toxicity. The new finding of impaired BMD in the high DU subgroup has now been detected in two consecutive surveillance visits. While this is a biologically plausible uranium effect, it is not reflected in other measures of bone metabolism in the full cohort, which have largely been within normal limits. However, ongoing accrual of the U burden from fragment absorption over time and the effect of aging further impairing BMD suggest the need for future surveillance assessments of this cohort.

Disposal of Uranium and Thorium Entering the Human Digestive System before Reaching the Blood by Adsorption on Simethicone and Forming a Non-absorbable Compound: A Full in vitro Analysis

Introduction: This method was applied to form a non-absorbable complex with uranium and thorium swallowed with contaminated dust or other sources to get rid of them before absorption into the blood and discarded outside the body. A non-GIT absorbable simethicone was used in this method for the adsorption of uranium (VI) and thorium (IV) from a solution similar to the gastrointestinal tract pH medium. Materials and Methods: Accurately measured 9 mg of pure standard uranyl nitrate and simethicone emulsion in concentration range (100-300 mg) at 37±1°C for 20 min in pH ranges like the medium of the stomach and intestine then take the supernatant after centrifugation to make sure of decreasing of the concentration of uranium and thorium ions by ICP Mass Spectroscopy (ICP-MS). Results and Discussion: The data recorded for different total uranium and thorium concentrations reveal convergent behavior. Increasing simethicone concentration inside the safe dose shifts the sorption of uranium and thorium to 100 % of the total concentration, calculated t and F values were compared with the reference method and the proposed method was equally precise and accurate. Conclusion: The data indicate that the method can successfully be applied for the complete adsorption of uranium and thorium on simethicone from GIT before reaching the blood.

Estimated of U, Rn and Po Concentrations in Smokers Blood Samples Collected from Babylon, Iraq

Because of the greats pressures on humans, there are resorted to smoking without knowing its effects on health. Such symptoms include adult lung cancer, cardiovascular, respiratory infections, kidney failure, congenital abnormalities and chronic bronchitis. Uranium and radon estimation has carried out in 100 smoker and Non-smoker blood samples from Babylon, Iraq, using solid state nuclear track detector (CR-39). The results have been shown the total uranium concentrations in blood smokers and non-smokers samples to be 1.02 ± 0.26 ppb and 0.86 ± 0.17 ppb respectively. On the other side, the total concentrations of radon in blood smokers and non-smokers samples 4.98 ± 0.79 Bqm−3 and 3.59 ± 0.28 Bqm−3 respectively. The total concentrations of uranium and radon in blood samples of smokers are greater than non- smokers blood samples. While, the total polonium (POW) and (POS) for smoker and non- smoker samples to be 0.527 KBqm−3 - 0.127 KBqm−3 and from 0.378 KBqm−3 to 0.091 KBqm–3 respectively. These studies conclude the smoking causes an increase in the concentration of uranium and radon and polonium in the blood of smokers.

Molar absorptivities of U(VI), U(IV), and Pu(III) in nitric acid solutions of various concentrations relevant to developing nuclear fuel recycling flowsheets

A number of inconsistencies in the literature was revealed while developing on-line spectrophotometric monitoring tools for determining aqueous phase actinide concentrations in a tributyl phosphate based solvent extraction flowsheet. This prompted a re-evaluation of the molar absorptivities of U(VI), U(IV) and Pu(III) ions in nitric acid (0.5–4 M). In this paper, our measured molar absorptivity values are reported and compared to the available technical literature data. Results of spectrophotometric analysis of grab samples from a counter-current solvent extraction flowsheet test show satisfactory agreement with total uranium and plutonium concentrations determined in the same samples by ICP-MS.

Mineralogical investigation of fine clastic rocks from Central Sarawak, Malaysia

The reduction in the conventional resources and insistent request for hydrocarbons and energy lead us to look forward for the increasing interest in unconventional resources by exploring new technologies for the national economy and local utilization in Malaysia. Upper Mesozoic-Cenozoic is considered the age of Central Sarawak Formations. This paper attempts to evaluate the clay mineralogy, depositional environment, gamma ray evaluation and the relationship between total organic carbon and uranium concentration of the Nyalau, Tatau, Begrih, Liang and Belaga Formation which eventually comprise black shales and mudstones using spectral gamma ray (SGR), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), XRD clay separation and total organic content (TOC%). The results from SGR indicate that the formations composed mainly of kaolinite, smectite and chlorite. These results are confirmed by XRD, XRD clay separation and FESEM with the presence of illite as a dominant clay mineral component. Based on Th/U ratios which vary between 0.42 and 3.95, the formations are expected to be deposited in the reduced marine environment. Results from calculated API (90.76–233.32 API) reveal the ability of the clay minerals to absorb uranium and thorium through cation exchange capacity. The relationship between TOC% and U cross plots also show a significant positive correlation. The presence of high U concentrations in the formations is possible because of their relatively higher clay contents and the existence of organic matter.

Measurement of uranium distribution coefficient and 235U/238U ratio in soils affected by Fukushima dai-ichi nuclear power plant accident

Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted radioactive contamination in soil due to deposition of mainly radiocesium as well as many long-lived radionuclides surrounding a large area around FDNPP. Depending upon environmental conditions, radionuclides in soil can be mobilized in aquatic systems. Therefore, the fate and transfer of these radionuclides in the soil water system is very important for radiation protection and dose assessment. In the present study, soil and water samples were collected from contaminated areas around FDNPP. Inductively coupled plasma mass spectrometry (ICP-MS) is used for total uranium concentration. Emphasis has been given on isotope ratio measurement of 235U/238U ratio using thermal ionization mass spectrometry (TIMS) that gives us the idea about its contamination during accident. For the migration behavior, its distribution coefficient (Kd) has been determined using laboratory batch method. Chemical characterization of soil with respect to different parameters has been carried out. The effect of these soil parameters on distribution coefficient of uranium has been studied in order to explain the radionuclide mobility in this particular area. The distribution coefficient values for uranium are found to vary from 30 to 36000 L/kg. A large variation in the distribution coefficient values shows the retention or mobility of uranium is highly dependent on soil characteristics in the particular area. This variation is explained with respect to soil pH, Fe, Mn, CaCO3 and organic content. There is a very good correlation of uranium Kd obtained with Fe content. There is no enrichment of 235U has been noticed in the studied area.

Surveillance results and bone effects in the Gulf War depleted uranium-exposed cohort

ABSTRACTA small group of Gulf War I veterans wounded in depleted uranium (DU) friendly-fire incidents have been monitored in a clinical surveillance program since 1993. During the spring of 2017, 42 members of the cohort were evaluated with a protocol which includes exposure monitoring for total and isotopic uranium concentrations in urine and a comprehensive assessment of health outcomes including measures of bone metabolism, and for participants >50 years, bone mineral density (BMD) determination. Elevated urine U concentrations were observed in cohort members with retained DU shrapnel fragments. Only the mean serum estradiol concentration, a marker of bone metabolism, was found to be significantly different for lower-vs- higher urine U (uU) cohort sub-groups. For the first time, a significant deficit in BMD was observed in the over age 50, high uU sub-group. After more than 25 years since first exposure to DU, an aging cohort of military veterans continues to exhibit few U-related adverse health effects in known target organs of U toxicity. The new finding of reduced BMD in older cohort members, while biologically plausible, was not suggested by other measures of bone metabolism in the full (all ages) cohort, as these were predominantly within normal limits over time. Only estradiol was recently found to display a difference as a function of uU grouping. As BMD is further impacted by aging and the U-burden from fragment absorption accrues in this cohort, a U effect may be clarified in future surveillance visits.

Uranium content in groundwater by laser fluorimetry; method validation and dose assessment

In this study, the total uranium concentration was determined in groundwater samples used for irrigation and/or drinking purposes and collected from private wells in Al Sharqiya region, Saudi Arabia. The uranium concentrations were measured by laser fluorimetry preceded by radiochemical treatment to eliminate the quenching effect due to the high total dissolved solids content in the groundwater samples. For method validation, some of the measured samples were analyzed for uranium isotopic activities and measured by alpha spectrometry. The results of the uranium concentrations obtained by laser fluorimetry and alpha spectrometry were in good agreement. The uranium concentrations in all the samples were below the World Health Organization (WHO) recommended limit of 30 μg L−1. Two different approaches were followed to assess the annual effective dose from the ingestion of uranium in the analyzed groundwater samples. The annual effective doses determined by the two approaches were found to be in agreement, and varied from 2.9 to 10.2 μSv y−1, with a mean value of 6.1 μSv y−1, which is far below the WHO recommended level of 100 μSv/y. The modified laser fluorimetric procedure was found to be a good tool compared with other techniques for direct measurement of uranium concentrations in high total dissolved solids groundwater samples at low levels.

Electronic Absorption Spectra of Uranium(V) Species in Fused Alkali Chlorides

Alkali chloride based melts can be used in pyrochemical reprocessing various types of spent nuclear fuels, especially those of fast neutron reactors. There is a possibility of refabricating uranium oxide or mixed uranium-plutonium oxide fuel by electrodeposition of UO2 or (U,Pu)O2 from chloride melts containing uranyl (or a mixture of uranyl and plutonyl) ions. At high temperatures uranyl chloro species undergo decomposition yielding UO2 + ions and finally UO2. Increasing temperature and lowering partial pressure of chlorine in the atmosphere above the melt shifts the equilibrium towards the decomposition products. In fact, uranium(V) ions are often present in uranyl-containing melts and, if unaccounted for, result in increased current efficiency of UO2 electrodeposition process. Electronic absorption spectroscopy allows a convenient method for detecting and measuring concentration of uranium(V) in uranyl-containing electrolytes. Absorption spectra of uranium(V) species in fused salts were reported over fifty years ago but still remain the least studied especially from the quantitative side concerning molar absorption (extinction) coefficient values. Uranium(V), f 1-electron configuration, absorbs in the visible region of the spectrum and the spectra have there two broad bands with the maxima around 620 and 775 nm not overlapping with the absorption of uranium(VI) ions, Fig. These bands correspond to two f–f transitions in UO2Cl4 3– complex ion, i.e., φ5u → 3π1u and φ5u → 3π3u. The aim of the present work was studying the effect of temperature and cationic melt composition on the absorption spectra of uranium(V) ions and determining molar absorption coefficients. The measurements were performed in individual alkali chlorides and their mixtures of various compositions including LiCl, CsCl, LiCl–KCl, LiCl–KCl–CsCl, NaCl–KCl, NaCl–CsCl. The temperature range varied from 350 to 850 oC depending on the melt. Uranium(V) ions were obtained in situ by reducing uranium(VI) ions with hydrogen. Uranium dioxide was also produced but no soluble uranium(IV) species in the melt were detected. After recording the spectrum a sample of the melt was taken and analyzed for the total uranium concentration and the mean uranium oxidation state which always was between five and six. From that, concentration of U(V) and V(VI) ions in the melt were calculated and U(V) extinction coefficients determined. The results obtained allow determination of U(V) concentration in technological electrolytes. Acknowledgement. This work was supported by the Ministry of Education and Science of the Russian Federation (project No. 4.5062.2017/8.9). Fig. Electronic absorption spectra of LiCl–KCl based melts containing U(VI) ions (line 1) and a mixture of U(VI) and U(V) ions at a 3 : 2 ratio (line 2). Total uranium concentration 0.038 mol/l, T = 550 oC. Figure 1

Geochemical evaluation of uranium sequestration from field-scale infiltration and injection of polyphosphate solutions in contaminated Hanford sediments

To remediate persistent groundwater uranium contamination in the 300 Area of the Hanford Site, located in southeast Washington State, U.S.A., approximately 7 million liters of polyphosphate solutions (mixture of 90% orthophosphate and 10% pyrophosphate) were delivered in high concentrations to the vadose zone and top of the aquifer over a 13-day period via infiltration and injection. The persistence of uranium in the aquifer is attributed to leaching of residual uranium contamination from the vadose zone by periodic rewetting due to fluctuating water table controlled by daily and seasonal variations of nearby Columbia river stage.The remedy relies on in-situ availability of Ca2+, primarily from cation-exchange and dissolution of carbonate mineral phases, to form calcium phosphate (Ca-P) bearing precipitates that incorporate and adsorb available uranium and form a relatively insoluble coating on sediments thereby reducing the dissolution of residual uranium bearing mineral phases. During injection and infiltration some dissolution of mineral phases is expected to occur along with rapid nucleation of Ca-P and the resulting precipitates are likely to incorporate components from the dissolving phases.The phosphate loading following treatment is calculated to be about 1000–2500 μg/g of sediment surface exposed. Of this amount, approximately 50–650 μg/g is associated with the solid phase that is extractable with acetic acid indicating association with carbonate phase. The observations at the monitoring wells during remedy implementation indicate an initial decrease in pH and an increase in dissolved uranium concentration with delayed breakthrough of phosphate due to reactions with mineral surfaces. Following the initial breakthrough, as the phosphate concentrations increase the uranium concentrations show a sharp decline and then remain low afterwards. Comparison of total uranium concentration profiles from collocated pre- and post-treatment borehole sediment samples indicate limited uranium leaching to the aquifer. The total uranium concentrations remained within the range of variability expected in the field.Sequential extraction tests conducted on sediment samples indicate that prior to treatment uranium is associated primarily with crystalline oxides of iron and clay minerals and to a lesser extent with carbonate minerals. In the post-treatment samples, appreciable reduction in uranium fraction associated with crystalline oxides of iron and clay minerals is observed indicating that uranium has been remobilized due to mineral dissolution, which later complexed with Ca-P-carbonate phases. The formation of surface complex of calcium-carbonate-phosphate likely structurally incorporated or surface adsorbed any available uranium in solution. Surface complexation with oxyhydroxides of iron (and other trace metals) also occurred.To evaluate the significant reactions resulting from introduction of phosphate bearing solutions a reactive transport model is developed to simulate the infiltration event. The results indicate that the extent of HPO42− reaction front is a net result of several reactions. As HPO42− is added to the sediments, the resulting deprotonation reactions lead to excess H+ and pH reduction that are buffered via surface complexation reactions and mineral phase dissolution. The cycle of deprotonation followed by consumption of H+ will continue as long as supply of both phosphate and reacting iron oxyhydroxide surfaces and minerals, primarily uranium bearing carbonates, uranium silicates, and calcite, are maintained. Due to excess supply, the phosphate will react with the available calcium (primarily from ion-exchange reactions) and start forming Ca-P bearing precipitates. In this process, any uranium in the solution will adsorb or get bound to forming precipitate and be sequestered.

Health effects following subacute exposure to geogenic dust collected from active drainage surfaces (Nellis Dunes Recreation Area, Las Vegas, NV).

The specific health effects of direct inhalation of fine minerogenic dusts generated by natural soil surfaces remain poorly known and relatively little researched. To learn more about this exposure and its contribution to human health effects, we surveyed surface sediment and characterized dust from the Nellis Dunes Recreation Area (NDRA) in Clark County, Nevada, a popular off-road vehicle (ORV) recreational site. Dry drainage systems at NDRA are commonly used as natural trail systems for ORV recreation; these surfaces also are characterized by high concentrations of heavy metals. Geogenic dust with a median diameter of 4.05μm, collected from drainage surfaces at NDRA contained a total elemental concentration of aluminum (79,651μg/g), vanadium (100μg/g), chromium (54μg/g), manganese (753μg/g), iron (33,266μg/g), cobalt (14μg/g), copper (37μg/g) zinc (135μg/g), arsenic (71μg/g), strontium (666μg/g), cesium (15μg/g), lead (34μg/g), and uranium (54.9μg/g). Adult female B6C3F1 mice exposed via oropharyngeal aspiration to 0.01-100mgdust/kg body weight, four times, a week apart, for 28-days, were evaluated for immuno- and neurotoxicological outcomes 24h after the last exposure. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100mg/kg. Splenic lymphocytic subpopulations, hematological and clinical chemistry parameters were affected. In brain tissue, antibodies against NF-68, and GFAP were not affected, whereas IgM antibodies against MBP were reduced by 26.6% only in the highest dose group. A lowest observed adverse effect level (LOAEL) of 0.1mg/kg/day and a no observed adverse effect level (NOAEL) of 0.01mg/kg/day were derived based on the antigen primary IgM responses after subacute exposure to this geogenic dust.

Investigating Uranium Concentrations in Groundwaters in the State of Idaho Using Kinetic Phosphorescence Analysis and Inductively Coupled Plasma Mass Spectrometry.

The determination of uranium concentrations in natural water samples is of great interest due to the environmental consequences of this radionuclide. In this study, 380 groundwater samples from various locations within the state of Idaho were analyzed using two different techniques. The first method was Kinetic Phosphorescence Analysis (KPA), which gives the total uranium concentrations in water samples. The second analysis method was inductively coupled plasma mass spectrometry (ICP- MS). This method determines the total uranium concentration as well as the separate isotope concentrations of uranium. The U/U isotopic ratio was also measured for each sample to confirm that there was no depleted or enriched uranium present. The results were compared and mapped separately from each other. The study also found that in some areas of the state, natural uranium concentrations are relatively high.

The U.S. Department of Veterans' Affairs depleted uranium exposed cohort at 25 Years: Longitudinal surveillance results

BackgroundA small group of Gulf War I veterans wounded in depleted uranium (DU) friendly-fire incidents have been monitored for health changes in a clinical surveillance program at the Veterans Affairs Medical Center, Baltimore since 1994. MethodsDuring the spring of 2015, an in-patient clinical surveillance protocol was performed on 36 members of the cohort, including exposure monitoring for total and isotopic uranium concentrations in urine and a comprehensive assessment of health outcomes. ResultsOn-going mobilization of U from embedded fragments is evidenced by elevated urine U concentrations. The DU isotopic signature is observed principally in participants possessing embedded fragments. Those with only an inhalation exposure have lower urine U concentration and a natural isotopic signature. ConclusionsAt 25 years since first exposure to DU, an aging cohort of military veterans continues to show no U-related health effects in known target organs of U toxicity. As U body burden continues to accrue from in-situ mobilization from metal fragment depots, and increases with exposure duration, critical tissue-specific U concentration thresholds may be reached, thus recommending on-going surveillance of this veteran cohort.

Multibiomarker toxicity characterization of uranium mine drainages to the fish Carassius auratus.

The release of acidic effluents, naturally enriched in metals and radionuclides, is the main legacy of uranium mines. Generally, metals dissolved by these acidic effluents can cause significant alterations in exposed organisms, with distinct toxicological outcomes. In this study, 72 individuals of the freshwater fish species Carassius auratus were exposed in situ for different periods (8, 16, 24, and 48h) to water from a pond (treatment pond (TP)) with a chemically treated effluent and a reference pond (PRP), in the vicinity of the Cunha Baixa uranium mine (Portugal). Comparing the water of the two ponds, the PRP pond was characterized by higher pH and oxygen values and lower conductivity and hardness values. Regarding total metal concentrations, among others, magnesium (56,000μg/L), sodium (17,400μg/L), zinc (86μg/L), manganese (6340μg/L), and uranium (1380μg/L) concentrations in the TP pond were above the values obtained for the PRP pond. The values of manganese and uranium exceeded the values of quality criteria established for surface waters for cyprinids and for irrigation purposes. After exposure to pond water, significant differences were recorded for several biomarkers: (i) between ponds for acetylcholinesterase (AChE) with higher activities for animals from the PRP and glutathione-S-transferase (GST) activities that were particularly enhanced in animals from the TP pond; (ii) between ponds and exposure periods for lactate dehydrogenase (LDH) activity, since organisms from PRP pond presented always higher values than those from the TP pond, and among these, organisms exposed for the longer period presented a further depression in LDH activity; and (iii) between exposure periods for erythrocyte micronucleus. GSTs and LDH were the most sensitive biomarkers within the timeframe of the in situ assay performed. Despite the alleged efficacy of the chemical treatment (evidenced by a significantly lower pH), some metals persisted in the treated effluent (TP pond), potentially contributing to the induction of oxidative stress or increased conjugation metabolic activity in fish.