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.     

The use of radium isotopic ratio in groundwater as a tool for pollution source identificatioin

Radium isotopes were measured in groundwater near a radioactive storage facility with contained pasty residues from monazite and industrial processing sealed in concerete reserouirs. The concentration of radium isotopes in the water was slightly higher than found in the normal drinking water. The measured²²⁸Ra to²²⁵Ra ratio in the groundwater is not compatible with calculations of radium isotopes ingrow and docay in cake II for different elapsed times, leaving mesothorium cake as the most likely source of contamination.     

Uranium and thorium exposures associated with conventional mining

Internal contamination with radioactive materials of mining workers is a common problem in Brazil. This is caused by the presence of uranium, thorium, and their natural decay series associated with the mined ore. The clear examples are the workers at the niobium mine located in the state of Goiás. The niobium is associated with considerable quantities of uranium and thorium, but the mine is not legally subject to radiation protection requirements.Twenty mine workers were evaluated using in vitro bioassay techniques (urine and feces). The fecal samples were analyzed by alpha spectrometry using the method developed in the Bioassay Laboratory of the Instituto de Radioproteção e Dosimetria/CNEN which evaluates thorium and uranium isotopes simultaneously. Minor modifications were introduced to measure a higher level of activity, around 1 Bq of uranium per sample. The urine samples were analyzed by alpha spectrometry for thorium and by fluorimetry for uranium. The results obtained show that a control of the occupationally-exposed workers is necessary.     

Determination of radium isotopes in mine waters through alpha- and beta-activities measured by liquid scintillation spectrometry

This paper presents a method for the determination of radium isotopes in mineralised mine waters, based on the separation of alpha- and beta-intensities measured in the precipitate by a liquid scintillation spectrometer in two time intervals (1 day and 7 days) after radium precipitation. The count rates of -particles give not only the concentration of alpha emitters (²²⁶Ra and²²⁴Ra), but also make possible to find the -counting efficiency of the system and through that-to determine the concentration of the -emitting radium isotope (²²⁸Ra) with higher accuracy. An improved chemical procedure was elaborated. By this method radium isotopes in different water samples were determined, in wide range of concentrations, from about 0.06 Bq/dm³ in potable water to more than 100 Bq/dm³ in some mine brines. As an example some analytical results are given. The detection limit, defined as three standard deviations, is-for both radium isotopes –0.03 Bq/dm³ (for intial volume of water sample equal to about 1 dm³ and for counting time of each measurement not longer than 1 hour).     

Separation and determination of uranium and radium-226 in phosphorites and their industrial derivatives by extraction chromatography

An extraction chromatographic method based on microporous polyethylene (Microthene) supporting tri-n-octylphosphine oxide (TOPO) was used to separate uranium and²²⁶Ra from phosphorites and their industrial derivatives. Uranium was then determined by fluorimetry and by alpha-spectrometry after electroplating, and radium by precipitation as Ba(Ra)SO₄ and alpha counting with a ZnS(Ag) alpha detector. The method was checked by using an IAEA phosphorite sample having a certified uranium concentration. Some phosphorite, phosphoric acid and plaster samples supplied by an Italian industrial plant were analyzed; uranium isotopes always resulted in radioactive secular equilibrium.     

Determination of uranium and thorium concentration in some Egyptian rock samples

Uranium (U) and thorium (Th) isotopes and their several radioactive descendants found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. Phosphate rocks are really rich natural sources of uranium and thorium among the other minerals forming the earth's crust. U and Th concentrations in some Egyptian phosphate samples were determined using a nuclear track registration methodology and -ray spectroscopy. The resulting latent tracks from all -decaying isotopes in both U and Th series were recorded in plastic detectors. A uniquely sensitive polycarbonate CR-39 nuclear detector was used. Results showed that the U and Th concentration in the samples studied range from about 4.0 up to 35.0 ppm and from 11.0 to 124.0 ppm, respectively. Results are discussed within the frame work of track formation methodology in plastic and -ray spectroscopic analysis.     

Alpha-recoil atoms of plutonium in the environment

The -recoil effect of²³⁹Pu has been observed in environmental samples and theN ₅ ^P /N₅ ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10^–5 and 10^–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10^–7 and 10^–6 (atom/atom), while that of uranium mineral is about 10^–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.     

Determination of radium isotopes by BaSO4 coprecipitation for the preparation of alpha-spectrometric sources

A coprecipitation procedure for the preparation of -spectrometric sources for radium, using BaSO₄ as carrier, has been applied to the determination of alpha radium isotopes in water samples. The use of¹³³Ba as a suitable tracer for radium determination and possible losses of radon isotopes from the sources are studied and discussed.     

Actinides in the near release from the Chernobyl NPP accident

Actinide elements concentrations in the products of near release from CNPP accident were estimated. The data on uranium,²³⁷Np,²⁴¹Am and plutonium and curium isotopes content in fuel particles are given. Sums of -emitting radionuclides and plutonium isotopes in reactor graphite particles and of uranium,²⁴²Cm,^239+240Pu isotopes in the soil and aerosol samples were also determined. By 1989 soil and dust contamination in near release of the accident is due to long-lived -emitting plutonium isotopes.     

Mobilization of radionuclides from uranium mill tailings and related waste materials in anaerobic environments

Specific extraction studies in our laboratory have shown that iron and manganese oxide- and alkaline earth sulfate minerals are important hosts of radium in uranium mill tailings. Iron- and sulfate-reducing bacteria may enhance the release of radium (and its analog barium) from uranium mill tailings, oil field pipe scale [a major technologically enhanced naturally occurring radioactive material (TENORM) waste], and jarosite (a common mineral in sulfuric acid processed-tailings). These research findings are reviewed and discussed in the context of nuclear waste forms (such as barium sulfate matrices), radioactive waste management practices, and geochemical environments in the Earth's surficial and shallow subsurface regions.     

Did the radioactive contamination in Hungary due to the disaster at the Chernobyl nuclear power station had a biopositive effect on plants?

Due to the disaster at the Chernobyl nuclear power station /26.04. 1986, USSR/ the radioactive contamination level /e.g.,¹³⁴Cs,¹³⁷Cs/ of the biosphere in Hungary increased significantly. The external -dose burden from the contaminated ground surface and atmosphere, and the radioactive isotopes taken up directly through the leaves and indirectly from the soil through the root system had a low-dose effect on the plants which was in the dose-range of stimulation /biopositive effect/.     

Determination of macroconstituents and trace elements in naturally occurring radioactive material in oil exploration waste products

Naturally occurring radioactive materials (NORM) contain radionuclides, such as radium, thorium, and uranium. The existence of NORM remains an issue for oil and gas exploration because once the material becomes concentrated through technological activity, it becomes a radioactive contamination hazard or a radioactive waste. Pipes and tanks used to handle large volumes of produced water at some oil-field sites are coated with scale deposits that contain high levels ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb. Experiments were conducted using thermal and epithermal neutron activation analysis and Compton suppression for the determination of macroconstituents and trace elements in the radioactive scale sample.     

Radium,uranium and thorium concentrations in low specific activity scales and in waters of some oil and gas production plants

Low specific activity scales consisting of alkaline earth metal carbonates and sulfates are often present in some gaseous and liquid hydrocarbon plants; these scales contain a certain concentration of radium, uranium and thorium, which can cause a risk of -irradiation and of internal radiocontamination when they must be mechanically removed. That being stated,²³⁸U,²³²Th and²²⁶Ra were determined in scales, sludges and waters coming from different plants.²³⁸U and²³²Th concentrations were found very low; the isotopes²³⁸U and²³⁴U resulted in radioactive equilibrium, whilst²³²Th and²²⁸Th were not always in equilibrium.²²⁶Ra concentration was higher in scales and sludges than in waters.     

Remediation of soil/concrete contaminated with uranium and radium by biological method

Biological method was studied for remediation of soil/concrete contaminated with uranium and radium. Optimum experiment conditions for mixing ratios of penatron and soil, and the pH of soil was obtained through several bioremediations with soil contaminated with uranium and radium. It was found that an optimum mixing ratio of penatron for bioremediation of uranium soil was 1 %. Also, the optimum pH condition for bioremediation of soil contaminated with uranium and radium was 7.5. The removal efficiencies of uranium and radium from higher concentration of soil were rather reduced in comparison with those from lower concentration of soil. Meanwhile, the removal of uranium and radium in concrete by bioremediation is possible but the removal rate from concrete was slower than that from soil. The removal efficiencies of uranium and radium from soil under injection of 1 % penatron at pH 7.5 for 120 days were 81.2 and 81.6 %, respectively, and the removal efficiencies of uranium and radium from concrete under the same condition were 63.0 and 45.2 %, respectively. Beyond 30 days, removal rates of uranium and radium from soil and concrete by bioremediation was very slow.     

Determination of radioactive nuclides of uranium and thorium series and estimation of α-flux in LSI constituent materials

Gamma-rays of nuclides of uranium and thorium series in silicone resin and ceramics were measured with a Ge(Li) detector. The state of radioactive equilibrium was determined by comparing the concentrations of uranium and thorium with the radioactive concentrations of²¹⁴Pb and²¹²Pb. The radioactive equilibrium was attained in silicone resin but not in ceramics. The -flux was calculated from the concentrations of uranium and thorium and their daughter nuclides. The calculated values of -flux agreed with that of -flux measured.     

Determination and evaluation of natural radioactivity and heavy metal levels in the aquatic environment of trans-boundary rivers: Maritza,Tundja and Arda

The main problem in the trans-boundary river system is that heavy metal and radioactive pollution can cause long-term effects on ecosystems. Therefore the natural radioactivity and heavy metal levels in the Maritza, Tundja and Arda Rivers, common for Bulgaria and Turkey, were determined for 3 years period (2007–2010). Gross alpha, gross beta and total radium isotopes activities, uranium and heavy metal concentrations of the surface water of the rivers were investigated and also terrestrial gamma and gamma dose rate were measured. The results were compared with reported data from other countries of the world and the recommended international standards. The results gathered in this study may provide background data on the natural radioactive and heavy metal levels of these trans-boundary rivers.     

Distribution of uranium in groundwaters of Bathinda and Mansa districts of Punjab,India: inferences from an isotope hydrochemical study

This paper presents the isotope hydrochemical results of groundwaters from southwest Punjab for assessing the uranium contamination and evaluating the factors leading to elevated uranium concentration. A total of 35 samples covering shallow and deep zones were collected for hydrochemistry and isotopes. Uranium concentration ranges between 2.3 and 357 µg L^?1 and 66% of the samples are contaminated. Both shallow and deep zones show U contamination but high incidences are noticed in shallow zone. Hydrochemical correlations infer geological sources rather than anthropogenic sources responsible for U contamination. Isotopically there is no clear distinction between high and low U groundwater.     

Determination of natural radioactivity in public drinking water quality assessment

The determination of ₉₀Sr and the gross particleactivity originating from radium isotopes was performed on water samples atvarious stages of treatment taken from water treatment plants before distributionto the consumers.     

Activity ratios of natural uranium in surface waters

The enrichment of²³⁴U in ground waters is a well established experiments fact. In the course of measurements of uranium contamination in rivers of the Guadiana basin we have found the contamination near the uranium mines with the equilibrium isotope ratios of uranium. With distance from the mines we found not only the expected decrease in contamination but also an increasing enrichment of the lighter isotopes. For the²³⁵U isotope, this is the first observation with good separation and low interference between the most significant peaks of each isotope.     

Determination of234U/238U and235U/238U ratios from commercially available uranium compounds by α-spectrometry

The²³⁴U/²³⁸U and²³⁵U/²³⁸U ratios from uranium compounds by -spectrometry technique have been obtained. Ten commercially available uranium reagents were analyzed. The well-separated peaks corresponding to uranium isotopes are evident, providing an energy spectrum of the -particles of uranium isotopes. It was found that some commerical uranium salts were depleted in²³⁴U and²³⁵U.