Search Results

You are looking at 101 - 110 of 10,163 items for :

  • "concentration" x
  • All content x
Clear All

Abstract  

Fourty two soil samples were collected to a depth of 20 cm from the Aegean Region of Turkey. The activity concentrations of 226Ra in the samples were determined by a radioanalytical method. The radiochemical yield for pure 226Ra was found to be 90.02±2.74%. The average concentration of 226Ra was 0.150 Bq.g-1 and its distribution fitted a normal curve. The average absorbed dose rate was found to be 61 nGy.h-1. The data were evaluated to explain of 226Ra distribution in the agricultural area and compared with other results in the literature.

Restricted access

Abstract  

Uranium and thorium have been determined in natural water samples by concentration on a cation-exchange resin, separation on an anionexchange resin and by measuring spectrophotometrically the compounds formed by U/IV/ and Th/IV/ with Arsenazo III. The recovery yield is higher than 90% for Th and about 80% for U.

Restricted access

Abstract  

Five types of building material of different quality and from different sources were analyzed for uranium and thorium using instrumental neutron activation analysis /INAA/. The concentration of thorium was found to be about 3–5 times higher than uranium while the activities were about the same. The total activities of both elements was found to be between 1–4 pCi g–1.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: D. I. Strumińska, D. I. Strumińska, D. I. Strumińska, B. Skwarzec, B. Skwarzec, and B. Skwarzec

Summary  

241Pu concentrations were calculated indirectly in different compartments of the southern Baltic ecosystem by the activity measurements of241Am isotope from the increase of theb-emitting241Pu at 16-18 years after the Chernobyl accident. Enhanced levels of241Pu were observed in all analyzed samples. Maximum values (0.408 and 0.367 mBq. g-1d.w.) of the estimated241Pu concentrations were found in sediments of Internal Puck Bay and Gdańsk Bay, respectively, and in the suspended matter from water of Gdańsk Bay (77.8 mBq.g-1d.w.). The highest241Pu/239+240Pu activity ratio was found in the suspended matter (1500) and water (140). The241Pu activity of the air dust was very high in April 1986, 3643±34.3 mBq.g-1d.w., and the241Pu/239+240Pu activity ratio was 56, but the highest241Pu/239+240Pu activity ratio of the air dust was measured in August. Then the241Pu concentration in air dust decreased quickly to values similar to those before the Chernobyl accident.This study provides new data for the 241Pu concentrations in various compartments of the Baltic Sea ecosystem.

Restricted access

Abstract  

A method for the determination of the industrial source of air pollution is described. The method is based on the analysis of elemental composition of dust samples taken at a single station and the relationships among concentrations of metals emitted by each kind of industrial plants. The method was experimentally confirmed in two industrial districts of Poland.

Restricted access

Abstract  

Milk was collected over a four-month period from three representative sectors of Puerto Rico. Instrumental neutron activation analysis (INAA) performed on the samples showed that the mercury concentration was slightly higher than the safe upper limit set by the World Health Organisation on food products. INAA for cadmium yielded high values when compared with atomic absorption.

Restricted access
Acta Veterinaria Hungarica
Authors: Anna Maleszka, Nina Smolinska, Anna Nitkiewicz, Marta Kiezun, Kamil Dobrzyn, Joanna Czerwinska, Karol Szeszko, and Tadeusz Kaminski

., Dafopoulos, K., Kosmas, G., Kallitsaris, A., Pournaras, S. and Messinis, I. E. (2009): Effect of ovarian hormones on serum adiponectin and resistin concentrations. Fertil. Steril. 91 , 1189–1194. Messinis I. E

Restricted access

Abstract  

The solvent extraction behavior of radioioine and astatine has been investigated under various conditions in order to compare the extraction behavior of astatine with radioiodine at tracer concentration. In this study, basic tracer solutions of astatine and radioiodine were extracted into the CS2 solution under various conditions. Astatine existed as a pure species in the tracer solution and formed cationic compound in the acidic solution which was also extracted into the organic solvent instantaneously. On the other hand, radioiodine existed as a complex in the tracer solution and was partly extracted into the organic solvent at tracer concentration. The observed different extraction behavior of astatine and radioiodine were consistently explained by the respective proposed extraction reaction schemes.

Restricted access

Abstract  

The sorption behavior of cesium on montmorillonite type clay was studied by using radioactivity measurements. Concentrations of Cs+ ions ranged from 10–6 to 10–2M. Cesium retention reduced with increasing salt concentration which was varied between 10–4 and 10–1M. Selectivity coefficients KCs–Na for the exchange between Cs and Na were calculated for different equivalent fractions of Cs on the solid phase. Using theK Cs–Na values, free energy change was found to be 7.8 kJ/mol. The data could be fitted to a Freundlich isotherm, and empirical Freundlich parameters enabled the generation of a site distribution function. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm, a mean energy of sorption of 8.6 kJ/mole was calculated which corresponds to the energy of ion exchange reactions. The values of energy changes calculated by using two different methods were in good agreement.

Restricted access

Abstract  

The paper presents and discusses radon activity concentrations in Cypriot groundwater systems as a function of the background lithology and seasonal/meteorological conditions using an airborne radon monitoring system (ARM) after separation of radon by out-gassing. Radiometric analysis of groundwater samples obtained from non-contaminated systems showed that radon concentration in groundwaters varies strongly (0.1–10 Bq L−1) depending mainly on the hosting geological matrix but also to lesser degree on atmospheric/meteorological conditions. The associated excess annual dose has been estimated to range between 10−6 and 10−4 mSv y−1, which is an insignificant contribution to the radiation exposure of the Cypriot population caused by airborne radon (0.5 ± 0.4 mSv y−1).

Restricted access