Uranium determination in water samples with elevated salinity from Southern Poland by micro coprecipitation using alpha spectrometry

Due to the importance of water in human life, its quality must be strictly controlled; so simple and reliable analytical methods must be available. For this purpose a rapid procedure for the determination of uranium isotopes in natural water samples with elevated salinity was adopted. It was tested in 16 water samples from Upper and Lower Silesia Regions in Poland. Water samples had salinity in a range of 290–26,925 mg l^{− 1}.In water samples the concentrations of ²³⁴U and ²³⁸U ranged from 2.07 to 52.08 mBq l^{– 1} and from 2.18 to 43.38 mBq l^{– 1} respectively, while ²³⁵U level was below MDA (0.7 mBq l^{− 1}).The isotopic ratio of ²³⁴U/²³⁸U varies in the range from 0.949 to 3.344 in all investigated waters which means that there is usually no radioactive equilibrium between the parent nuclide ²³⁸U and its daughter product ²³⁴U.These results do not show a correlation between total dissolved solids (TDS) values and concentration of dissolved uranium isotopes.Committed effective dose for adults due to uranium intake as a result of drinking water usage was in range of 0.15–3.29 µSv y^{− 1} with an average value of 1.09 µSv y^{− 1} far below the 100 µSv y^{− 1} WHO recommendation.     

Determination of uranium and thorium isotopes in mineral spring waters

Concentrations levels of uranium and thorium isotopes have been analyzed in the m mineral spring waters of a high background region of Brazil: Poços de Caldas and Águas da Prata. The procedure was based on the determination of²³⁸U,²³⁴U,²³²Th,²³⁰Th and²²⁸Th by -spectrometry after separation and purification of the isotopes of interest by using anion-exchange chromatography and preparation of the samples for -measurements by electrodeposition. The concentration varied from <1.1 to 28.4 mBq.l^–1 and from <1.6 to 141 mBq.l^–1 for²³⁸U and²³⁴U, respectively. Thorium isotope measurements varied from <0.2 to 1.8 mBq.l^–1 from <0.3 to 4.9 mBq.l^–1 and from <0.8 to 19.9 mBq.l^–1 for²³²Th,²³⁰Th and²²⁸Th, respectively. Calculations of thorium and uranium isotopic activity ratios were carried out giving values ranging from 1.9 to 7.2, from 1.2 to 3.0 and from 7.7 to 15.3 for²³⁴U/²³⁸U,²³⁰Th/²³²Th and²²⁸Th/²³²Th, respectively. The effective doses due to the intake of²³⁸U and²³⁴U present in these waters are expected to reach values up to 1.4×10^–3 mSv y^–1 and 8.0×10^–3 mSv y^–1, respectively.     

Natural radioactivity levels in mineral,therapeutic and spring waters in Tunisia

Radioactivity measurements were carried out in 26 groundwater samples from Tunisia. Activity concentrations of uranium were studied by radiochemical separation procedures followed by alpha spectrometry and that for radium isotopes by gamma-ray spectrometry.The results show that, the concentrations in water samples range from 1.2 to 69 mBq/L.1, 1.3 to 153.4 mBq/L, 2.0 to 1630.0 mBq/L and 2.0 to 1032.0 mBq/L for ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸Ra, respectively. The U and Ra activity concentrations are low and similar to those published for other regions in the world. The natural radioactivity levels in the investigated samples are generally increased from mineral waters through therapeutic to the spring waters.The results show that a correlation between total dissolved solids (TDS) values and the ²²⁶Ra concentrations was found to be high indicating that ²⁶⁶Ra has a high affinity towards the majority of mineral elements dissolved in these waters. High correlation coefficients were also observed between ²²⁶Ra content and chloride ions for Cl^?–Na⁺ water types. This can be explained by the fact that radium forms a complex with chloride and in this form is more soluble.The isotopic ratio of ²³⁴U/²³⁸U and ²²⁶Ra/²³⁴U varies in the range from 0.8 to 2.6 and 0.6 to 360.8, respectively, in all investigated waters, which means that there is no radioactive equilibrium between the two members of the ²³⁸U series. The fractionation of isotopes of a given element may occur because of preferential leaching of one, or by the direct action of recoil during radioactive decay.The annual effective doses due to ingestion of the mineral waters have been estimated to be well below the 0.1 mSv/y reference dose level.     

Study of uranium isotopic composition in groundwater and deviation from secular equilibrium condition

Uranium concentration in groundwater reflect both redox conditions and uranium content in host rock. In the present study an attempt has been made to study the uranium concentration and activity ratios of uranium isotopes to present the geochemical conditions of the groundwater in Malwa region of Punjab state, India and the reason for high uranium levels and variation of activity ratios from secular equilibrium conditions. Uranium concentration in groundwater samples was found to be in the range of 13.9 ± 1.2 to 172.8 ± 12.3 μg/l with an average value of 72.9 μg/l which is higher than the national and international guideline values. On the basis of uranium concentration, the groundwater of the study region may be classified as oxidized aquifer on normal uranium content strata (20 %) or oxidized aquifer on enhanced uranium content strata (80 %). The ²³⁸U, ²³⁵U and ²³⁴U isotopic concentration in groundwater samples was found to be in the range of 89.2–1534.5, 4.4–68.5, and 76.4–1386.2 mBq/l, respectively. Activity ratios of ²³⁴U/²³⁸U varies from 0.94 to 1.85 with a mean value of 1.11 which is close to unity that shows secular equilibrium condition. High value of ²³⁴U isotope than ²³⁸U may be due to alpha recoil phenomenon. The plot of AR of ²³⁴U/²³⁸U against the total uranium content in log scale reveals that the groundwaters of the study region either belongs to stable accumulation or normal oxidized aquifer.     

Radioanalytical investigations of uranium concentrations in natural spring, mineral, spa and drinking waters in Hungary

Within this work, the activity concentrations of uranium isotopes (²³⁴U, ²³⁵U, and ²³⁸U) were analyzed in some of the popular and regularly consumed Hungarian mineral-, spring-, therapeutic waters and tap waters. Samples were selected randomly and were taken from different regions of Hungary (Balaton Upland, Bükk Mountain, Somogy Hills, Mez?föld, and Lake Hévíz). Concentration (mBq L^?1) of ²³⁴U, ²³⁵U, and ²³⁸U in the waters varied from 1.1 to 685.2, from <0.3 to 7.9, and from 0.8 to 231.6 respectively. In general, the highest uranium concentrations were measured in spring waters, while the lowest were found in tap waters. In most cases radioactive disequilibrium was observed between uranium isotopes (²³⁴U and ²³⁸U). The activity ratio between ²³⁴U and ²³⁸U varies from 0.57 to 4.97. The calculated doses for the analyzed samples of spring water are in the range 0.07–32.39 μSv year^?1 with an average 4.32 μSv year^?1. This is well below the 100 μSv year^?1 reference level of the committed effective dose recommended by WHO and the EU Council. The other naturally occurring alpha emitting radionuclides (²²⁶Ra and ²¹⁰Po) will be analyzed later to complete the dose assessment. This study provides preliminary information for consumers and authorities about their internal radiological exposure risk due to annual intake of uranium isotopes via water consumption.     

Anomalously high 234U/238U activity ratios of Tatsunokuchi hot spring waters, Ishikawa Prefecture, Japan

Uranium concentration and the ²³⁴U/²³⁸U activity ratio have been measured for the Tatsunokuchi hot spring waters of Ishikawa Prefecture in Japan, collected periodically over a long period (1977-2000). The concentration of ²³⁸U varied drastically between 0.045 and 1.02 mBq/l (a factor of about 20), while the ²³⁴U concentration was almost unchanged, ranging from 2.30 to 3.07 mBq/l. Resultant ²³⁴U/²³⁸U activity ratios showed a wide range from 2.7 to 51. Equilibrium calculation by using the geochemical code showed that U for one end-member representing low uranium contents and very high ²³⁴U/²³⁸U ratios was expected to exist as UO₂(CO₃)₂ ^2-. By using the U isotopic and ¹⁴C dating methods, the age of this water was roughly estimated to be in the range of 10⁴-10⁵ years.     

Isotopic uranium analysis in urine samples by alpha spectrometry

Urine assay is the preferred method for monitoring accidental or chronic internal intake of uranium into the human body. A new radiochemical separation procedure has been developed to provide isotopic uranium analysis in urine samples. In the procedure, uranium is co-precipitated with hydrous titanium oxide (HTiO) from urine matrix, and is then purified by anion exchange chromatographic column. Alpha spectrometry is used for isotopic uranium analysis after preparation of a thin-layer counting source by cerium fluoride micro-precipitation. Replicate spike and procedural blank samples were prepared and measured to validate the procedure. The ²³²U tracer was utilized for chemical recovery correction, and an average recovery of 76.2 ± 8.1% was found for 1400 mL urine samples. With 48 h of counting, the minimum detectable activity concentrations were determined to be 0.43, 0.21 and 0.42 mBq/L for ²³⁸U, ²³⁵U and ²³⁴U, respectively.     

Concentrations and activity ratios of radionuclides around the nuclear facilities in Korea

The concentrations and activity ratios of the radionuclides aroundthe nuclear facilities located in Taejon were determined. The concentrationsand activity ratios of uranium isotopes in the downstream decreased with increasingdistances from the point of discharge and reached the reference value after4 km. The concentrations of uranium isotopes in the brook around LWR fuelfabrication facilities were lower than those in the downstream around HWRand LWR fuel fabrication facilities, while the activity ratios of ²³⁴U/²³⁸U in the brook were higher than those in the downstream.The concentrations of uranium isotopes in the ground water measured quarterlywere variable depending on the sampling time. The concentrations of the grossalpha of airborne particulates collected around the nuclear facilities werefound to be in the narrow range of 0.02 to 0.10 mBq/m³ with a meanvalue of 0.05 mBq/m 3 . Both the concentrations and activity ratios of ¹³⁷Cs, ^239,240Pu and ⁹⁰ Sr around the nuclearfacilities were not very different from the worldwide fallout. The concentrationsof uranium isotopes in the soil samples around the nuclear facilities werevery close to natural background levels.     

Recovery and pre-concentration of americium (III) from dilute acid solutions using an emulsion liquid membrane containing di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant

Radiochemical results of U isotopes (²³⁴U, ²³⁵U and ²³⁸U) and their activity ratios are reported for well waters as local sources of drinking waters collected from the ten settlements around the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The results show that ²³⁸U varies widely from 3.6 to 356 mBq/L (0.3–28.7 μg/L), with a factor of about 100. The ²³⁸U concentrations in some water samples from Dolon, Tailan, Sarzhal and Karaul settlements are comparable to or higher than the World Health Organization’s restrictive proposed guideline of 15 μg (U)/L. The ²³⁴U/²³⁸U activity ratios in the measured water samples are higher than 1, and vary between 1.1 and 7.9, being mostly from 1.5 to 3. The measured ²³⁵U/²³⁸U activity ratios are around 0.046, indicating that U in these well waters is of natural origin. It is probable that the elevated concentration of ²³⁸U found in some settlements around the SNTS is not due to the close-in fallout from nuclear explosions at the SNTS, but rather to the intensive weathering of rocks including U there. The calculated effective doses to adults resulting from consumption of the investigated waters are in the range 1.0–18.7 μSv/y. Those doses are lower than WHO and IAEA reference value (100 μSv/y) for drinking water.     

Intake of 210Po, 234U and 238U radionuclides with beer in Poland

²³⁸U, ²³⁴U and ²¹⁰Po activity concentrations were determined in beer in Poland by alpha-spectrometry with low-level activity silicon detectors. The results revealed that the mean concentrations of ²³⁸U, ²³⁴U and ²¹⁰Po in the analyzed beer samples were 4.63, 4.11 and 4.94 mBq·dm⁻³, respectively, the highest in Tyskie (5.71 for ²¹⁰Po, 5.06 for ²³⁴U and 6.11 for ²³⁸U) and the lowest in Lech (2.49 for ²¹⁰Po). The effective radiation dose due to uranium and polonium ingestions by beer was calculated and were compared to the effective radiation dose from drinking water. This revised version was published online in July 2006 with corrections to the Cover Date.     

222Rn content and234U/238U activity ratio in groundwaters

Geochemical radioanalytical studies of groundwater were performed in the valleys of Villa de Reyes and San Luis Potosi (Mexico). The experiments were designed to measure radon and uranium content and²³⁴U/²³⁸U activity ratio in groundwater samples taken from wells in these sites and at the Nuclear Center of Salazar, Mexico.²²²Rn content varied depending on the sample source, reaching a maximum value of 235 pCi/l; uranium concentration results were less than 1 g/1 and²³⁴U/²³⁸U activity ratios were close to equilibrium.     

<Superscript>234</Superscript>U/<Superscript>238</Superscript>U and <Superscript>235</Superscript>U/<Superscript>238</Superscript>U ratios in domestic water from the environs of Obuasi mine in Ghana

Activity concentrations of ²³⁸U, ²³⁵U and ²³⁴U were determined in different sources of drinking water at the Obuasi gold mines and its surrounding areas in Ghana. Water samples collected from the mines and its surrounding areas were analyzed using direct gamma-ray spectrometry and neutron activation analysis. The ²³⁴U/²³⁸U and ²³⁵U/²³⁸U ratios were calculated and the mean values range from 1.27 to 1.38 and from 0.044 to 0.045 respectively. The average ²³⁴U/²³⁸U ratio was from 1.27 for groundwater to 1.38 for treated water, demonstrating the lack of equilibrium. The average ²³⁵U/²³⁸U activity ratio is 0.045, indicating that only natural uranium was detected in the samples investigated.     

Natural radioactivity in bioassay by alpha-spectrometry measurements

Personnel of nuclear facilities are checked regularly for internal contamination by bioassay measurements. Although these persons are generally not involved in any incident, natural radioactivity from U, Th and Ra can be found in their urine or faeces. Uranium total activity in urine has been found with a range of 0.051 to 3.0 mBq/24 h and in faeces from 14.5 to 380 mBq/d. ²³⁴U/²³⁸U ratio for urine is 1.48 but this ratio varies from 0.47 to 19. By comparison, the ²³⁴U/²³⁸U ratio found in urine from workers in volved with natural uranium or 4.5% enriched uranium is 1.0 and around 4.0 respectively. ²³⁰Th, ²²⁸Th and sometimes ²³²Th have also been detected. The total thorium activity varies from 0.137 to 5.6 mBq/24 h in urine and from 9 to 183 mBq/d in faeces. ²²⁸Th has generally been found in excess of ²³²Th. All these measurements were performed by alpha-spectrometry. The few ²²⁶Ra results have been measured using the Lucas or emanation method.     

Radionuclides of 210Po, 234U and 238U in drinking bottled mineral water in Poland

A study of the radioactive content of drinking mineral bottled water in Poland was carried out. ²¹⁰Po,²³⁸U and ²³⁴U activity concentrations were determined by alpha-spectrometry with low-level-activity silicon detectors. The results revealed that the mean concentration of ²¹⁰Po,²³⁸U and ²³⁴U in analyzed water sample were 1.28, 0.80 and 0.80 mBq^.dm^-3, respectively. The effective doses due to the polonium and uranium emissions were calculated for bottled drinking water.     

Radiochemical characterization of spring waters in Balaton Upland, Hungary, estimation of radiation dose to members of public

Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L^{− 1}) of ²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y^{− 1} with an average 18.2 μSv y^{− 1} .This is well below the 100 μSv y^{− 1} reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y^{− 1}, mainly due to the contribution from radium (²²⁶Ra, ²²⁴Ra) and ²¹⁰Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake.     

Isotopic concentration of uranium from alpha spectrum of electrodeposited source on 4H-SiC detector at 500 °C

4H-SiC alpha detectors were fabricated with a 21-μm thick depletion depth and were packaged into a stainless-steel casing with a mineral insulation cable and a standard BNC connector. The packaged detectors had a resolution of 0.624% FWHM at 5.486 MeV prior to salt immersion. The detectors were then immersed in a LiCl–KCl–UCl₃ molten salt at 500 °C, from which a thin layer of depleted uranium was electrodeposited onto the detectors. Alpha particle emission spectra were collected from the electrodeposited source. The energy resolution of the surviving detector was 2.29% FWHM at 4.198 MeV and was sufficient to separate the ²³⁴U from ²³⁸U alpha emissions (577 keV difference). The ²³⁴U/²³⁸U activity ratio and the isotopic concentrations of ²³⁴U and ²³⁸U were determined and are representative of the uranium source used in the electrodeposition.

     

Uranium isotope anomaly in minerals

A series of leaching experiments with HF, HCl, HNO₃ were carried out on samples of uranium minerals (uraninite and carnotite samples). Anomalously high²³⁴U/²³⁸U ratios were observed in some uranium fractions. The observed²³⁴U/²³⁸U activity ratios varied between the values of 1.019±0.155 and 6.210±0.504 (Ci/Ci), while the bulk carnotite sample had an activity ratio of 1.010±0.005 (Ci/Ci). These results are interpreted as due to alpha-recoil effect and changes in oxidation state of uranium.     

The transfer of uranium from sediment to water along Jucar River, Spain

The effect of sediment size, pH, temperature and conductivity on the transfer of uranium from sediment to water has been studied. The uranium concentration and the²³⁴U/²³⁸U,²³⁵U/²³⁸U activity ratios were measured in water, sediments and suspended matter sampled from Jucar River, using low level alpha-spectrometry. Distribution factors were obtained from these measurements. A more detailed sampling was done in the neighbourhood of the Cofrentes Nuclear Plant (Valencia, Spain). Total uranium activity,²³⁴U/²³⁸U activity ratio and distribution factors for²³⁴U and²³⁸U were found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes.     

The Radionuclides 234U, 238U and 210Po in Drinking Water in Gdańsk Agglomeration (Poland)

Consumption of natural water (public and bottled) is very important for people from a radiological point of view. Uranium and polonium alpha-emitters belong to the most radiotoxic elements for human. In the paper, a study of the radioactive content of drinking (public) water in Gdask agglomeration (Poland) was carried out. ²³⁸U, ²³⁴U and ²¹⁰Po activity concentrations were determined by alpha-spectrometry with low-level-activity silicon detectors. The results revealed that the mean concentration of ²³⁸U, ²³⁴U and ²¹⁰Po in analyzed water sample were 2.76, 2.86 and 0.48 mBq·dm^–3, respectively. Finally, effective does due to uranium and polonium emissions were calculated for drinking water samples for the inhabitants of the agglomeration.     

Determination of234U/238U activity ratios in Syrian phosphates

The concentrations of uranium and the²³⁴U/²³⁸U ratio in natural Syrian phosphates were measured by gamma- and alpha-ray spectroscopy. The²³⁴U/²³⁸U activity ratios showed that uranium in Syrian phosphate is in equilibrium under the climatic conditions. Soma anomalous observations in these ratios were explained by earlier leaching of the phosphate by water (rain or other).