A modified method for the determination of uranium in Nb/Ta minerals by LED fluorimetry

A modified LED fluorimetry determination of uranium in Nb/Ta minerals has been developed. The mineral is brought into solution by fusion with mixed phosphate flux (NaH₂PO₄, H₂O and Na₂HPO₄). Iron quenches uranium fluorescence when it is present above the ratio of (iron to uranium) 100. Uranium is separated in ethyl acetate by solvent extraction and then stripped back into pyrophosphate buffer (pH ~ 7) prior to its LED fluorimetry determination. This modified method has been applied for the determination of uranium in synthetic mixtures and Nb/Ta minerals including Certified Reference Materials (X1807) with high degree of accuracy and precision.

     

A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques

The main objective of this work is the accurate measurement of uranium in the potable water sources of Muktsar district of Punjab, India. In the present work, a laser fluorimetry technique was used for the analysis of uranium. Inductively coupled plasma mass spectrometry (ICPMS) technique was also applied to verify and compare the uranium content analyzed using laser technique. About 16 samples from waterworks, bore wells, and hand pumps that supply the drinking water to local population were collected for this purpose. An indigenous laser fluorimeter supplied by RRCAT, Indore was employed for the analysis. Uranium concentrations obtained were in the range from 0 to 10???g?L^?1 in ten samples, 11?C30???g?L^?1 in three samples, and more than 100???g?L^?1 in three samples namely Channu ground water, Warning Khera pump, and Killanwale village hand pump. The USEPA guideline value for uranium in safe drinking water is 30???g?L^?1. Also, a data comparison with similar studies carried out in other countries is presented.     

Actinide bioassays by ICPMS

The ever-increasing sensitivity of ICPMS continues to expand the technique’s application in the field of health physics. Enhancements in sample introduction and instrument design over the last few years have resulted in improving the ICPMS detection limit from ∼10 ng/l to≤0.1 ng/l. This additional sensitivity provides greater flexibility in the analysis of long-lived radionuclides in biological fluids, and requires only minimal sample preparation of urine for uranium analysis; the described 3-minute abbreviated matrix separation provides detection limits that are comparable to or better than alpha counting. For urine samples tested having concentrations that exceed the accepted administrative limit for total uranium (0.2 μg/day), isotopic analysis by ICPMS (e.g., determining the presence of²³⁶U, or measuring appropriate uranium isotope ratios) provides a reliable indication of occupational exposure. Our laboratory also utilizes ICPMS in a study examining uranium dissolution rate classification of dust collected at the perimeter of a nuclear facility. Specific details regarding these and other health physics applications are featured, including our group’s participation in assisting the DOE with the evaluation of ICPMS as a cost-effective alternative to fission-track analysis for the routine determination of²³⁹Pu in urine.     

Uranium and thorium isotopes from Kazakhstan

Uranium and thorium concentrations in water and in soil from Kazakhstan have been investigated. In some sampling points the uranium concentrations of drinking water, exceeded the WHO guideline level for drinking water. Thus, the human effect of uranium exposure from drinking water in these areas is significant. However, soil samples were the same as in the Nature. Irrigation systems in these areas would be easy for water carried in the drains mix with groundwater. The results here suggest that the uranium passes into the groundwater through the agriculture land by the above mechanism.     

Chitosan impregnated Ca-alginate: a new hybrid material for removal of uranium from potable water

Novel sorbent, chitosan impregnated calcium alginate (Cal-Alg-Chi) bead was developed to sorb uranium from potable water without compromising water quality parameters. The uptake study in batch mode, showed more than 98% sorption of uranium in the concentration range of 0.1–50 µg mL⁻¹. Cal-Alg-Chi beads, reduced the concentration of uranium below 15 ng mL⁻¹ from 100 to 450 ng mL⁻¹ in groundwater collected from effected regions in India. Sorption isotherm followed Langmuir model and maximum sorption capacity was evaluated as 36.04 mg g⁻¹. The sorption was endothermic with ΔG ⁰ value of −9.76 kJ mol⁻¹ and kinetics followed pseudo-second order rate law.

     

Assessment of the polluting effects of the Iponri-Alaka Canal,Lagos State,Nigeria

ABSTRACT

The polluting effects of Iponri-Alaka Canal in Surulere area of Lagos State on the environment have been studied using six sampling points. The study aimed at assessing the effects of exposure to pollutants on humans and other life forms. The quality of air, wastewater and sediments was assessed between March and August 2017. The concentrations of SO₂ and H₂S were measured using MSA Altair 5X. Temperature, pH and DO were measured in-situ using Thermometer, pH meter and Winkler method, respectively. TSS, TDS, TS, TA, TH, BOD, chloride Cl^?, PO₄^3-, SO₄^2- and NO₃^? were determined using appropriate standard methods in the laboratory. EC and some heavy metals (Cr, Pb, Mn, Cd and Ni) concentrations were determined using conductivity meter and Atomic Absorption Spectroscopy, respectively. The results showed that pH, TS, DO and TH were well within the WHO and FEPA maximum limits. EC, SO₄^2- and TDS were observed to be higher than guideline values only at one sampling point. The TSS, BOD, TA, NO₃^? and PO₄^3- were higher than WHO and FEPA guideline limits at all sampling points. Cr was seen to be within, while Pb and Mn were higher than WHO and FEPA guideline values. Cd was higher than guideline values only at two sampling points. Ni was below detection concentration at all the sampling points.

The concentration of SO₂ was seen to be higher than WHO and NESREA guideline values at two sampling points, while H₂S concentration was higher than WHO limit at all the six sampling points.     

Development of a colorimetric test for quantification of uranium in drinking water

A colorimetric method was developed for the determination of uranium in groundwater. The detection limit for the method is approximately 25 μg/L uranium, which is below the maximum contaminant level for uranium in drinking water, 30 μg/L. The method is rapid and requires little technical training to conduct, allowing it to be used by consumers, in the laboratory, or in the field. The two-step technique involves preconcentrating uranium using a U/TEVA-2 extraction chromatographic resin followed by complexation with a pyridylazo indicator dye, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. If color change is visible to the eye, the concentration of uranium in groundwater is above the detection limit. Preconcentration using U/TEVA-2 also serves to eliminate metals that may interfere with the quantification of uranium.     

Uranium biosorption under dynamic conditions: Preliminary tests with Sargassum filipendula in real radioactive wastewater containing Ba, Cr, Fe, Mn, Pb, Ca and Mg

The biosorption of uranium by the seaweed Sargassum filipendula was investigated under dynamic conditions at various bed heights. Our results indicate that a bed height of 40.0 cm (111.9 g biomass) was the most efficient for long-term operation of the continuous system. Our results also indicate that the effluent solutions produced are in accordance with Brazilian legislation for safe discharge of uranium in aqueous streams. The efficiency of the process increased with an increase in bed height from 5.0 to 40.0 cm due to changes in the transfer zone. In treatment of a real effluent contaminated with uranium, stable heavy metals and essential metals, 64% of the uranium was biosorbed, as well as the stable heavy metals chromium, lead and barium. The essential metals calcium, magnesium, iron and manganese were not biosorbed by the seaweed, in fact, their concentrations in the solution increased due to ion-exchange mechanisms with the constituent polysaccharides of the biomass. Another important result was the 85–87% reduction of mass obtained after drying and calcination of the biomass. This is a relevant indication that long-term storage of biomass loaded with radionuclides and heavy metals is possible after concentration of the contaminants. In the present work, the reduction in total mass of the loaded biomass was considerable, thus facilitating storage of the contaminated seaweed.     

X-ray fluorescence analysis in environmental radiological surveillance using HPGe detectors

X-ray fluorescence (XRF) has been proven to be a valuable tool for determining trace quantities of heavy metals, such as uranium and lead, in different types of samples. The present paper demonstrates the applicability of XRF spectrometry to measure the concentrations of these heavy metals in samples from natural ore and soil. The values of uranium concentrations in rock from the Peña Blanca uranium ore, in Chihuahua, México, were calculated for the purpose of precertifying the rock powders samples. The comparison with other techniques, such as inductively coupled plasma atomic emission spectrometry, atomic absorption spectrometry, alpha spectrometry and electron microscopy, was used to complete the precertification process, so that the sample powders may be used as secondary standards. The source-sample-detector geometry and the incident angle are the most important factors for obtaining low detection limits. The selected system uses a ⁵⁷Co source of about 0.1 mCi to excite the K X-rays from uranium and lead. X-rays were recorded on a CANBERRA HPGe coaxial detector. The comparative results for two incident angles (90° and 180°) performed previously by other authors show that the best geometry is the backscattering geometry. In the present paper, using EGS4 code system with Monte Carlo simulation, it was possible to determine the location and distribution of background produced by the Compton edge in the optimized geometry. This procedure allowed to find the minimum detectable concentration of uranium and lead, which was experimentally calculated using standards. The possibility of performing in vivo measurements rapidly and easily, as well as the factors affecting accuracy and the minimum detectable concentration in several samples are also discussed.     

Determination of potentially toxic heavy metals in traditionally used medicinal plants for HIV/AIDS opportunistic infections in Ngamiland District in Northern Botswana

The determination of four potentially toxic heavy metals, arsenic, chromium, lead and nickel in twelve plant species used for the treatment of perceived HIV and AIDS-associated opportunistic infections by traditional healers in Ngamiland District in Northern Botswana, a metal mining area, was carried out using atomic absorption spectrometry. The medicinal plants; Dichrostachys cinerea, Maerua angolensis, Mimusops zeyheri, Albizia anthelmintica, Plumbago zeylanica, Combretum imberbe, Indigofera flavicans, Clerodendrum ternatum, Solanum panduriforme, Capparis tomentosa, Terminalia sericea and Maytenus senegalensis contained heavy metals in varying quantities: arsenic 0.19–0.54 μg g⁻¹, chromium 0.15–1.27 μg g⁻¹, lead 0.12–0.23 μg g⁻¹ and nickel 0.09–0.21 μg g⁻¹ of dry weight. Chromium was found to be the most abundant followed by arsenic and lead. Nickel was undetectable in nine plant species. M. senegalensis contained the largest amounts of arsenic, chromium and lead. All metals determined were below the WHO permissive maximum levels. The possible maximum weekly intakes of the heavy metals following treatment regimes were insignificant compared to the provisional tolerable weekly intake levels recommended by WHO and the Joint FAO/WHO Expert Committee on Food Additives. This suggests that heavy metal exposure to patients originating from consumption of traditional medicinal plant preparations is within non health-compromising limits.     

Elemental composition of drinking water supplies in three states in Southeastern Nigeria

The levels of some trace elements; Co, Mn, Cu, Zn, Cr, Cd, Pb, Fe, Hg, Se, As, Ni and minor elements; Na, K, Ca and Mg were determined in public drinking water supplies (public taps and groundwaters) in three states in Southeastern Nigeria using energy dispersive X-ray fluorescence spectrometry (EDXRF) and flame atomic absorption spectrometry (FAAS). The mean levels of most of the trace elements in the groundwater samples were below the World Health Organization (WHO) drinking water quality limits, the only exception being Hg whose mean value of 3.69 μg/l exceeded the WHO limit of 1.0 μg/l. Violations of the WHO limits were also observed for Fe, Zn, Se and Pb in some of the groundwater samples. In the public tap samples only Hg violated the WHO limit.     

Activity concentration of uranium in groundwater from uranium mineralized areas and its neighborhood

Uranium mineralization in parts of northeastern Nigeria necessitated its exploration during early eighties by the Nigeria Uranium Mining Company (NUMCO) which was later abandoned. During their course of decay, uranium isotopes pass through radioactive decay stage and eventually into stable isotope of lead. The course of concern for soluble uranium in groundwater especially from the mineralized areas include ionizing radiation, chemical toxicity and reproductive defects for which ingested uranium has been implicated to have caused. This study is aimed at assessing the levels of concentration of uranium in groundwater to ascertain its compliance with the World Health Organization’s (WHO) and the United State Environmental Protection Agency’s (EPA) guideline for uranium in drinking water. Thirty five groundwater samples were collected using EPA’s groundwater sampling protocol and analyzed at the Department of Geology, University of Cape Town using an Inductively Coupled Plasma Mass Spectrometric (ICP-MS) technique. Significant finding of this work was that there is radiological contamination of groundwater in the area. There is also an indication that the extent of radiological contamination is not much within the mineralized zones, therefore, there is likelihood that groundwater has acted as a medium of transporting and enhancing uranium in groundwater in an environment away from that of origin. About 5.7 % of the samples studied had uranium concentration above WHO and EPA’s maximum contaminant level of 30 μg/L which is a major concern for inhabitants of the area. It was also apparent that radiological contamination at the southwestern part of the study area extends into the adjacent sheet (sheet 152). Uranium concentration above set standards in those areas might have originated from rocks around established mineralized zones but was transported to those contaminated areas by groundwater that leaches across the host rock and subsequently mobilizing soluble uranium along with it.     

Uranium in groundwater from Western Haryana,India

This study was undertaken to assess uranium in groundwater and radiological and chemical risks associated with its ingestion in rural habitats in the vicinity of proposed nuclear power project in Western Haryana, India. Uranium concentration in the groundwater of the study area varied from 0.3 to 256.4 μg L^?1. Radiological risk calculated in the form of average life time dose was found 5.1 × 10^?2 mSv to the residents of the area from the ingestion of groundwater. The average cancer mortality and average cancer morbidity risk were calculated to be 4.9 × 10^?6 and 7.7 × 10^?6 respectively indicating the absence of carcinogenic risks. Chemical risk was in the range of 0.02–18.8 µg kg^?1 day^?1. Hazard quotient for 72 % samples was greater than unity which indicates health risk due to chemical toxicity of uranium in groundwater. The results indicate that uranium concentrations in the groundwater of the study area are important due to chemical risk than radiological risk.     

Bioremediation of effluent from a uranium mill tailings repository in South China by <Emphasis Type="Italic">Azolla</Emphasis>–<Emphasis Type="Italic">Anabaena</Emphasis>

Hydroponic experiments were conducted on the removal of uranium, heavy metals and nutrients from the effluent of a uranium mill tailings repository in South China by Azolla–Anabaena. The plant–microbe symbiont was kept in the effluent for 30 days, and it was found that U, Fe, Mn, Cu, Zn, Pb, Cd, total phosphorus (TP), total nitrogen (TN) and SO₄^2? reduced by 87.6, 99.1, 98.8, 88.2, 91, 78.3, 77.5, 93.4, 98.7 and 76.7%, respectively. Specifically, the concentration of uranium reduced to 0.039 mg L^?1, which is below the limits of contaminants by the Department of Environmental Protection of China. The concentration of Fe, Cu, Zn, Pb, TP and TN in the effluent reached the quality standard for drinking water. The results showed that Azolla–Anabaena can be used for the bioremediation of the effluent from the uranium mill tailings repository.     

Uranium isotopes in carbonate aquifers of arid region setting

Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of ²³⁸U and ²³⁵U in groundwater of four selected locations in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for ²³⁵U and ²³⁸ U at 3–39 ng L^?1 (average: 18 ng L^?1) and 429–5,293 ng L^?1 (average: 2,508 ng L^?1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions.     

Determination of heavy metals and pesticides in ginseng products.

Medicinal plants may carry residuals of environmentally persistent pesticides or assimilate heavy metals in varying degrees. Several factors may influence contaminant accumulation, including species, level and duration of contaminant exposure, and topography. As part of a program for assessment of the quality of herbal medicines, we have analyzed 21 over-the-counter ginseng (Panax ginseng) products in various dosage forms. Chromium, mercury, and arsenic were undetectable above their limits of detection in both liquid and solid samples; while cadmium, lead, and nickel were present in the majority of samples. The chlorinated pesticide levels varied widely. In most samples, the total concentration of pesticides was below 100 ppb; while in 5 samples the total concentration exceeded 100 ppb.     

Assessment of chemo-radiological risk of naturally occurred uranium in groundwater from the Beed district,India

The main objective of study is assessment of chemo-radiological risk using measured concentrations of uranium in drinking water. For estimation of U concentration, LED Fluorimeter was used. For data accuracy, statistical tools were applied, geographical distribution GIS based software were used. To assess relation between uranium to other parameters, correlation test was performed. On the basis of presence of U in the water, hazard quotient, effective dose and cumulative dose for lifetime were estimated, it ranges from 0.001 to 1.09, 0.01–18.61 μSv year⁻¹ and 1.22–1303 μSv for lifetime correspondingly. The estimated ingested dose is well below than the suggested limit of 0.1 mSv.

     

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan,China

In order to fully understand the morphological characteristics and pollution status of heavy metals in the dewatered sludge of Huainan Municipal sewage treatment plant, the physical and chemical properties were analyzed, and the content and occurrence forms of heavy metals (As, Cu, Zn, Pb, Cd, Cr, and Ni) in the sludge were studied using the geological accumulation method (Igeo), risk assessment coding method (RAC), and potential ecological risk index method to evaluate the ecological risk. The results showed that the municipal sludge in Huainan was rich in nutrients, with good prospects for agricultural utilization. There were differences in the morphological distributions of different heavy metals. The Igeo values for Ni, As, Cr, and Pb were below 0. The results of RAC indicated that the risk level of Cr in sludge was a low risk, and those of other heavy metals were moderate risks. The potential ecological risk of Cd had the highest potential ecological risk, and the other six metals were of low ecological risk. This conclusion can provide basic data and a theoretical reference for the comprehensive utilization of sludge in sewage treatment plants.     

Determination of trace metals in seawater by an automated flow injection ion chromatograph pretreatment system with ICPMS

A novel flow injection ion chromatograph (FI-IC) system has been developed to fully automate pretreatment procedures for multi-elemental analysis of trace metals in seawater by inductively coupled plasma mass spectrometer (ICPMS). By combining 10-port, 2 position and 3-way valves in the FI-IC manifold, the system effectively increase sample throughput by simultaneously processing three seawater samples online for: sample loading, injection, buffering, preconcentration, matrix removal, metal elution, and sample collection. Forty-two seawater samples can be continuously processed without any manual handing. Each sample pretreatment takes about 10 min by consuming 25 mL of seawater and producing 5 mL of processed concentrated samples for multi-elemental offline analysis by ICPMS. The offline analysis improve analytical precision and significantly increase total numbers of isotopes determined by ICPMS, which include the metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn. The blank value and detection limits of trace metals using the system with ICPMS analysis all range from 0.1 to 10 parts per trillion (ppt), except Al, Fe, and Zn. The accuracy of the pretreatment system was validated by measuring open-ocean and coastal reference seawater, NASS-5 and CASS-4. Using the system with ICPMS analysis, we have obtained reliable trace metal concentrations in the water columns of the South China Sea. Possessing the features of full automation, high throughput, low blank, and low reagent volume used, the system automates and simplifies rigorous and complicated pretreatment procedures for multi-elemental analysis of trace metals in seawater and effectively enhances analytical capacity for trace metal analysis in environmental and seawater samples.     

Estimation of uranium in bioassay samples of occupational workers by laser fluorimetry

A newly established uranium processing facility has been commissioned at BARC, Trombay. Monitoring of occupational workers is essential to assess intake of uranium in this facility. A group of 21 workers was selected for bioassay monitoring to assess the existing urinary excretion levels of uranium before the commencement of actual work. Bioassay samples collected from these workers were analyzed by ion-exchange technique followed by laser fluorimetry. Standard addition method was followed for estimation of uranium concentration in the samples. The minimum detectable activity by this technique is about 0.2 ng. The range of uranium observed in these samples varies from 19 to 132 ng/L. Few of these samples were also analyzed by fission track analysis technique and the results were found to be comparable to those obtained by laser fluorimetry. The urinary excretion rate observed for the individual can be regarded as a ‘personal baseline’ and will be treated as the existing level of uranium in urine for these workers at the facility.