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1.
Water, plant and soil samples from forested area were analyzed in order to study the behavior of radionuclides in the forest ecosystem. The concentration of 137Cs in the soil decreased with depth, while stable Cs and 40K were almost constant. It is suggested that most of the 137Cs once entered in the forest ecosystem is trapped in the upper part of the soil.  相似文献   

2.
Studies on radioactive fallout from atmospheric nuclear weapons tests have been carried out at this laboratory since the mid-fifties. The data thus generated on the levels and composition of radioactive fallout in India has been published periodically. Consequent to the Chernobyl reactor accident in the USSR in April 1986, similar studies were carried out. A number of fairly active samples were collected from commercial aircraft which had flown over the USSR soon after the accident. Even though the levels of fallout from the Chernobyl reactor accident observed in India were not significant from a health hazard view point, the studies provided detailed information on differences in the composition of fallout from the accident and long term radiation exposures likely to accrue from the Chernobyl fallout as opposed to global fallout from atmospheric nuclear weapons tests. This paper presents the results and their interpretation on the above aspects.  相似文献   

3.
The distribution of137Cs through soil layers has been investigated by field sampling. The investigation deals with137Cs concentration found after the Chernobyl accident. The relationship between important soil characteristics, total precipitation and cesium distribution are analyzed. Cesium is strongly sorbed in the top soil layer and its migration downward is limited. Measurements performed over a 3-year period revealed that approximately 20–38 per cent of total137Cs is located in the upper soil layer.  相似文献   

4.
A review is presented on the separation of colloidal radionuclides from aqueous solutions involving the sorption and flotation methods.  相似文献   

5.
Rapid determination of 222Rn and 220Rn progeny (214Pb, 212Pb, 214Bi, 212Bi) is achievable using manganese dioxide (MnO2) precipitation with analysis by γ-spectrometry. This is of interest to environmental monitoring programmes that utilise gross activity methods to screen for anthropogenic radionuclides. The contribution from these naturally occurring radionuclides (NOR) varies, and is difficult to experimentally measure due to short half-lives (t ½ = 19.9 m–10.64 h) and low environmental activity (<0.1 Bq L?1). The extraction efficiency of the technique is above 90%, and above 80% for other nuclides (232Th, 238U, 235U, 228Ac, 226Ra, 224Ra, 210Pb, 54Mn). Short-lived NOR have been measured at two surface water locations, and indicates elevated 214Bi activity of 4.0 ± 1.1 Bq L?1.  相似文献   

6.
Six elements in several organs of mice fed with Zn deficient diet (Zn-def. mice) and those fed with control diet (control mice) were analyzed by INAA. Zinc concentrations in the organs of Zn-def. mice were not distinctly lower than those of control mice except for bone and pancreas. However, Ce content increased significantly in all organs of Zn-def. mice compared with control mice, indicating the partial substitution of Co with Zn in metal proteins or other materials for the Zn-def. mice.  相似文献   

7.
Journal of Radioanalytical and Nuclear Chemistry - This study describes the impact of dam construction at Sun Moon Lake, Taiwan, on lacustrine sedimentation. Analyses of the physical properties of...  相似文献   

8.
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.  相似文献   

9.
The radiation reduction yield of Fe3+ in complexes with various ligands (Cl, SO 4 2– , CN) in methanol-water solutions has been studied. The effect of the dose, pH, scavenger concentration and matrix composition on the reduction, yield of Fe3+ in the above complexes and in Fe(acac)3 was determined. Studies of methanol-water glasses (91) provided some interesting observations as to the effectiveness of scavenging the electrons by various ferric compounds. The effectiveness of scavenging decreases in the series Cl>SO 4 2– >CN. As opposed to Co(acac)3, Fe(acac)3 appeared to be an ineffective scavenger.  相似文献   

10.
The radioactivity of the Opa river — irrigated farmlands in the south western Nigeria was determined using an HpGe based, low-level passive gamma-counting system. With the exception of two isotopes, the main radionuclides analysed in the sample were the progenies of238U and232Th. The other two isotopes were the naturally occurring40K and the anthropogenic137Cs. The result obtained showed elevated levels of radioactivity from all detected radionuclides compared to the published data for this area. Enhanced levels of naturally occurring radionuclides is attributed to the use of phosphatic fertilizers for dry season vegetable cultivation along this river banks. The presence of the fission product137Cs could be traced to the fallouts occasioned by the various French nuclear tests in the Sahara desert, and probably, some effect of the more recent nuclear reactor accident at Chernobyl in 1986.  相似文献   

11.
The fallout caused by the accident of Chernobyl' nuclear reactor has been monitored in Niigata City (April 30-June 3, 1986). Twelve nuclides (131I, 132I, 129Te, 129mTe, 132Te, 134Cs, 136Cs, 137Cs, 103Ru, 99mTc, 140La, 140Ba) were identified in aerosol samples. The same nuclides plus 7Be were identified in rain-water. Gaseous and particle-bound 131I were separately trapped on a glass filter and a charcoal filter, respectively. Results indicate 50-60% of atmospheric 131I is gaseous and the rest is particle-bound. Chloroform extraction of rain-water revealed that 40-60% of 131I in the rain-water sample exists in the form of IO3- and 131IO3- (131IO4-)/131I- seemed to increase with the lapse of time after the accident.  相似文献   

12.
The distribution of different radionuclides depends on their speciation in the real fission product solution and the electric charge of the alumina. The pH-value is the main parameter that influences the disyribution coefficient. By combination of an acidic adsorption and an alkaline desorption process, the interesting fission molybdenum can be separated. The distribution ratios of the relevant radionuclides are described.  相似文献   

13.
An anion exchanger OSTION AT 0807 of Czechoslovak production was tested for the separation of radium, thorium, uranium and plutonium. According to the results, the separation process is suitable for analysis of atmospheric precipitation samples. Separation efficiency can be increased by the repetition of the procedures.  相似文献   

14.
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.  相似文献   

15.
R. Dams  J. Hoste 《Talanta》1964,11(12):1605-1612
An attempt to separate niobium and tantalum by precipitation from homogeneous solution by thermal decomposition of their peroxy complexes, in the presence of tannin and oxalate, has been only moderately successful. A more satisfactory separation of tantalum and niobium for ratios from 50:1 to 1:30 is obtained by extracting the bisulphate melt with ammonium oxalate before adding hydrogen peroxide, hydrochloric acid and tannin. For a tantalum/niobium ratio of 1:1 the niobium coprecipitation is reduced to 5 %. Furthermore, two alternative possibilities are presented: (1) a quantitative recovery of a tantalum precipitate at small oxalate and high tannin concentration, leaving 90% of the tantalum-free niobium in solution; (2) an 85 % recovery of niobium-free tantalum at high oxalate and small tannin concentration. A study of the coprecipitation process of niobium shows that the distribution coefficients follow a logarithmic pattern, true homogeneous mixed crystals being formed.  相似文献   

16.
Methods of extraction, clean-up and preconcentration normally reserved for organic trace analysis are considered with a view to applying such techniques to the developing field of organometallic speciation. The overview covers the main compartments of the natural environment; water, soil and sediment, plant and animal tissue.  相似文献   

17.
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.  相似文献   

18.
Separation of adsorbed radionuclides on diethylene glycol succinate (DGS) by diethylenetriaminepentaacetic acid (DTPA) was quantitatively performed. Adsorption between the radionuclides studied and DGS was attained at pH 5±0.5. Individual separations of60cobalt (II),90strontium (II),144cerium (III),233uranium (VI) and239plutonium (IV) were done by 25 ml of 10−4M of DTPA, as eluting agent, at different pH values.  相似文献   

19.
A method for systematic separation and determination of some neutron-activated nuclides and actinides is described. The method is designed to utilize stable isotopes and radioactive tracers as chemical yield monitors and to separate nuclides of interest from a single limited sample. Gravimetric, spectrophotometric, radiometric and X-ray fluorescence analysis were used for determination of chemical yields of the nuclides. Overall chemical yields generally ranged from 60–90%. Separated and purified nuclides were detected by -spectrometry or isotope dilution -spectrometry. The detection limit for neutron-activated nuclides is 107 nuclides and the precision is better than 3% RSD.  相似文献   

20.
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.  相似文献   

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