Measurement of radon exhalation rate from soil samples of Garhwal Himalaya, India

Laboratory experiment was performed for the measurement of radon exhalation rate from the soil samples collected from Garhwal Himalayas. This study is accompanied by the measurement of soil-gas radon concentration in the same area. Both results were compared with the geological formation and structure of the area. No correlation was observed between soil-gas radon concentration and radon exhalation rate. However, it was found to be controlled by the lithology, geological structure and uranium mineralization in the area. The relationship between radon emanation, geological formation and occurrence of high indoor radon concentration is discussed.     

Speciation of natural and antropogenic radionuclides in different sea sediment samples

A sequential extraction method consisting of six operationally-defined fractions was used to determine the geochemical partitioning of natural (U, Th,) and antropogenic (Pu, Am, ¹³⁷Cs) radionuclides in three sediment samples of different origin (Venice Lagoon, Adriatic Sea; Gaeta Gulf, Thyrrhenian Sea; IAEA-367, Enewetak Atoll, Central Pacific Ocean). Fe, Mn, Al, Ti, Ca, Sr, Pb, Ba, K were also determined in the different fractions to get more information about the chemical association of the single radionuclides. The experimental results were compared to those described in the literature for an IAEA-135 Sea Sediment collected in the Irish Sea in front of the Sellafield Plant (UK).     

Vertical distribution of the natural and artificial radionuclides in various soil profiles to investigate soil erosion

Vertical distributions of ¹³⁷Cs and ²¹⁰Pb in soil profiles were examined to study their availability in soil erosion at Gökova region where there exists intensive agricultural activities on sloppy fields. Since the mobility of these radionuclides depend on soil characteristics, soil samples were analyzed also for their physical and chemical properties. From ¹³⁷Cs inventories measured, erosion rates for cultivated and disturbed (no cultivation) soils were calculated to range from 79.1 to 6.5 t^.ha^-1.y^-1 and from 79.9 to 3.5 t^.ha^-1.y^-1, respectively. The ²¹⁰Pb technique is found to be not suitable for erosion determination for this area, presumably due to the coal-fired power plants operating in the region.     

Assessment of radiological impacts of natural radionuclides and radon exhalation rate measured in the soil samples of Himalayan foothills of Uttarakhand,India

Journal of Radioanalytical and Nuclear Chemistry - In order to assess the radiological baseline, the terrestrial radionuclide contents (226Ra, 232Th, and 40K) and radon exhalation rate were...     

Influence of freezing on physicochemical forms of natural and technogenic radionuclides in Chernozem soil

Sharp variations of different climatic parameters influence the transport, transfer, and deposition of contaminants in nature. Investigations of the impact of environmental temperature on the fractionation of radionuclides in soil are necessary for adequate assessment of their distribution and bioavailability in case of a nuclear accident. The impact of a sharp decrease of environmental temperature shortly after radioactive contamination on the physicochemical fractionation of natural and technogenic radionuclides in Chernozem soil and its influence on their potential migration ability and bioavailability in case of subsequent warming were evaluated. The soil was contaminated in a laboratory with ²⁴¹Am, ⁶⁰Co, ¹³⁷Cs, ²²⁸Ra, ²³⁴Th, and U and two temperature regimes were used for storage. Changes of the radionuclides association with various soil phases in the first weeks after contamination were studied. Physicochemical forms of ²⁴¹Am, ⁶⁰Co, ²²⁸Ra, ²³⁴Th, and U were determined using two sequential extraction procedures. The ion-exchangeable forms of ¹³⁷Cs were evaluated by single extraction with 1 M NH₄NO₃. The data showed that the freezing, following the radioisotope contamination of the soil, causes an increase of the amount of potentially mobile forms of radiocobalt, radiocesium, radium, and thorium and has an insignificant impact on the fractionation of americium and uranium.     

Activities of Pu radionuclides and 241Am in soil samples from an alpine pasture in Romania

Activity concentrations of Pu radioisotopes and ²⁴¹Am were determined in the organic and mineral layers of four soil sections collected in 1996, providing for the first time information on the levels of these radionuclides in soil samples from Romania. The investigated site was an alpine pasture located in the Charpathian Mountains, in an area found as one of the most affected in Romania after the Chernobyl accident. In the examined soil sections radioactive inventories were estimated to be 500 Bq/m² for ²⁴¹Pu, 115 Bq/m² for ^239+240Pu, 8 Bq/m² for ²³⁸Pu and 50 Bq/m² for ²⁴¹Am. On the basis of activity ratios in the soil profile, the source of the radioactive release is discussed.     

Distribution of natural radionuclides

The distribution of natural nuclides and of the effective specific radioactivity in processing of the sphene concentrate was studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1237–1240.Original Russian Text Copyright © 2004 by Melnik, Lokshin, Sedneva.     

Assessment of natural and fallout radioactivity in soil samples of Visakhapatnam

Environmental gamma radiation levels around the new Bhabha Atomic Research Centre site at Visakhapatnam have been assessed. Natural and anthropogenic radionuclide activity concentrations in soil samples collected were determined using high-resolution gamma spectroscopy. Average activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 38, 38, 230 and 520 Bq kg^?1, respectively. No anthropogenic radionuclide except fallout ¹³⁷Cs having mean concentration range ≤ 0.2–2.2 Bq kg^?1 was detected in the soil samples. The observed values are compared with the values reported for different areas in India and other parts of the world. The annual total external gamma radiation dose to the members of public estimated using the above observations ranged from 0.13 to 0.38 mSv y^?1 with an average of 0.25 mSv y^?1.     

Electrochemical determination of carbaryl oxidation in natural water and soil samples

An electrochemical method for the determination of carbaryl, after prior oxidation to 1,4-naphthoquinone in natural water and soils is reported. The coulometric oxidation of carbaryl at a platinum electrode was studied using 0.024 mol/L Britton-Robinson buffer (pH 7.0). The reduction of the oxidation product 1,4-naphthoquinone at a dropping mercury electrode was used for the indirect determination of carbaryl after separation on C₁₈ Sep-pak cartridges by differential pulse polarography (detection limits: 0.41 mg L^?1 of water and 0.47 mg kg^?1 of soil) and directly without separation by adsorptive stripping voltammetry (detection limits: 5 μg L^?1 of water and 7 μg kg^?1 of soil, for 75 s preconcentration time). Relative errors were lower than 3.7% and relative standard deviations smaller than 4.5%.     

Combined procedure for the determination of90Sr,241Am and Pu radionuclides in soil samples

A combined procedure for sequential determination of low level activity concentrations of⁹⁰Sr,²⁴¹Am and Pu radionuclides is described. The analysis of -emitters is performed by isotope dilution -spectrometry using²⁴²Pu or²³⁶Pu and²⁴³Am tracers. Strontium-90 is analyzed by liquid scintillation counting using the double energetic windows method. The method combines the well established, procedure for Pu analysis based on anion exchange, the powerful and selective method for Sr isolation based on extraction chromatography using Sr-Spec resin and finally it includes the application of the TRU-Spec column for separation and purification of the Am fraction. The radiochemical procedure was tested using IAEA reference and intercomparison materials. Major parameters of the procedure as well as advantages and drawbacks are discussed in detail.     

The leachability of some natural and man-made radionuclides from soil and sediments on acid attack

A radiotracer study was made of the leachability of some natural and man-made radionuclides from soils and sediments subjected to attack by various acid mixtures. Particular attention was paid to the nuclides²³⁸U,²³²Th, Pa (as²³³Pa) and Np (as²³⁹Np), since for these neutron activation can be used to study recoveries and/or to induce in situ radionuclides in samples. Thus conventional NAA allowed determination of total²³⁸U and²³²Th instrumentally, and also enabled analysis of leachates and residues by radiochemical or instrumental NAA. Activation of these nuclides produced samples endogenously labelled with²³³Pa and²³⁹Np whose behaviour on acid dissolution/leaching could be examined. Furthermore, comparison of neutron irradiated and non-irradiated samples allowed us to investigate the possibility of increased leachability induced by nuclear recoil reactions; however, this effect was negligible. We also investigated the acid leaching of americium adsorbed on the surface of sediment. In general, unsatisfactory leaching recoveries were found for²³³Pa,²³⁹Np and²³²Th for most materials, indicating the need for total dissolution procedures.     

Radiological assessment of natural radionuclides in soil from playgrounds in Southwestern Nigeria and evaluation of radiation dose

Journal of Radioanalytical and Nuclear Chemistry - The activity concentrations of natural radionuclides in soil from playground were determined by gamma spectrometry using NaI(Tl) detector. Annual...     

Microwave oven dissolution of geological samples: Novel application in the determination of natural decay series radionuclides

A microwave oven was utilised to decompose several geological materials by means of acid digestion. Dissolution was achieved in 5 min and²³⁸U,²³⁴U,²³²Th and²³⁰Th were all determined on the solutions by radiochemical separation and -spectrometry. The materials, which include a granite, an arkose, a river sediment and a nearshore marine sediment, display a large range in U and Th contents /Th/U ratio of 0.7 to 7: U content of 12 to 1400 Bq kg^–1/ and activity ratios /²³⁴U/²³⁸U of 0.95 to 1.50/. The data indicate that the microwave oven dissolution method produces data comparable to the traditional /open beaker/ method. Unit costs are, however, significantly reduced.     

Neutron moderation effects in phc contaiminated soil samples

Prompt gamma ray analysis of soil samples contaminated with petroleum hydrocarbons(PHC) like benzene was carried out using 14 MeV neutron beams. Intensities of silicon, carbon, oxygen, and hydrogen gamma rays were measured for soil samples containing 2.20–10.4 wt% benzene. With increasing benzene concentration, the intensity of the C gamma rays increased while those of Si, H, and O gamma rays decreased. The reduction in Si, H, and O gamma ray intensities may be due to increasing neutron moderation effect in benzene-contaminated soil samples. The experimental intensities of gamma rays are in good agreement with the calculated intensities.The neutron moderation effects in benzene contaminated soil samples are about 26% weaker than those reported for soil samples containing moisture. From the slopes of silicon gamma ray intensity as a function of benzene concentration as well as moisture concentration, a simple scheme has been suggested to correct for the loss in carbon counts caused by neutron moderation from PHC and moisture in the soil samples.     

Radiological hazard assessment of natural radionuclides and heavy metal pollution in deep mud samples of Van Lake,Turkey

Journal of Radioanalytical and Nuclear Chemistry - In the present investigation, thin layer activation technique has been employed to study the effectiveness of an amine derivative compound, namely...     

Measurement of actinides and long-lived radionuclides in large coral samples

Sequential separation and radiochemical determinations of low-level plutonium, americium, strontium, and cesium in soil and vegetation samples from coral atolls are described. Elmination of calcium matrix salts and interfering magnesium salts are explained. Data on measurement protocols and chemical yields are presented.     

Sorption of radionuclides on natural materials

Information about the sorption of radionuclides on natural materials used for cementation of liquid radioactive wastes (RAW) is important for predictions of migration rates of radionuclides in the products of fixation. Cementation process for conditioning liquid RAW uses, besides cement, materials which improve quality of products. In Czechoslovakia technology among these materials are clinoptilolite tuffit, mordenite tuff, tobermorite and fly ash. Liquid RAW issued from nuclear power plants contains the principal radionuclides⁶⁰Co,¹³⁴Cs and¹³⁷Cs, therefore, a sorption study of these radionuclides was carried out. pH of liquid RAW was 12.5–13.7 and salt content ca. 200 g·dm^–3. Results of sorption are given by distribution coefficients. The best results for cesium in those pH region and salt content had mordenite tuff D_Cs=100 dm³·kg^–1 and the worst results had fly ash D_Cs=4.1 dm³·kg^–1. The best results for cobalt in those solutions had tobermorite D_Co=38 dm³·kg^–1 and the worst results had fly ash D_Co=6.9 dm³·kg^–1.     

Determination of short-lived radionuclides in neutron-activated human head-hair samples

The Al, Na, Mn, Cl and Mg contents of human head-hair samples were determined by irradiating the samples in a thermal reactor and measuring their γ-activity by scintillation techniques. The concentration variations of these elements in hair samples originating from the same and different persons were studied.