共查询到20条相似文献,搜索用时 46 毫秒
1.
P. Mell J. Megyeri L. Riess Z. Máthé J. Csicsák K. Lázár 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):405-410
Summary Sorption of60Co,85Sr, 137Cs and125I have been studied on samples
originated from Boda (siltstone-) claystone formation (BCF) (Hungary). The
distribution of Kdvalues have been determined in static batch
experiments using natural groundwater. The order of sorption of isotopes was
Co>Cs>Sr>I, where iodine exhibits sorption properties in a modest
extent. The sorption isotherm was determined for Cs from measurements carried
out in 10-5-10-1M initial concentration range. The
isotherm can be described with non-linear Freundlich approximation in the range
of</o:p></p>
10-7-10-4M equilibrium concentration. At
concentrations >10-2M the isotherm achieves saturation. Hence, it is suggested that sorption
of Cs on BCF is dominated by cation-exchange reactions on the illite mineral
component. In the case of Co and Sr, precipitation reactions occurred during
the experiments performed with carrier-containing solutions. This can be
attributed to the low values of solubility product constants of SrCO3, SrSO4and Co(OH)2, formed from anions present in the
natural groundwater.</p>
</p> 相似文献
2.
M. S. Al-Masri A. Nashawati Y. Amin B. Al-Akel 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):289-295
Summary Transfer
of 226Ra, 85Sr and 137Cs from cow and sheep
milk to various Syrian dairy products has been evaluated. Dairy products
include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese,
liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The
results showed that the percentage of 226Ra, 85Sr and 137Cs
transferred from cow milk to milk cream (Pt=food
processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%,
respectively. Butter and liquid cheese were found to have the lowest percentage
of transferred 226Ra, 85Sr and 137Cs.
Most of the obtained Pt values of the studied radionuclides
in thick yogurt were relatively low in spite of the high processing
efficiencies of thick yogurt. Moreover, the transfer, Pt, of
the studied radionuclides from cow milk to the prepared cheese was higher than
those values determined for sheep milk. This is due to differences in chemical
compositions of each type of milk. On the other hand, the treatment of Native
cheese, most commonly consumed cheese in Syria, with different concentrations
of NaCl solutions showed that 137Cs was completely removed from
cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of 226Ra
and 80% of 85Sr were also decontaminated using 0-2.5% NaCl solutions
and soaking time of 48 hours. Based on the obtained results, industrialization
processes of the dairy products that resulted the removal of radionuclides have
been identified.</p>
</p> 相似文献
3.
S. Ueda K. Kondo J. Inaba H. Kutsukake K. Nakata 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):261-273
Summary In
order to evaluate the transport of 3H and 137Cs
radionuclides in semi-closed brackish Lake Obuchi, Japan, bordered by nuclear
fuel cycling facilities, a 3D-lower-trophic eco-hydrodynamic model has been
developed and validated. In a short-term prediction, 3H and 137Cs
activity levels in water should be in an agreement with field measurements. It
became clear that the results depended on the mixing of fresh water and
seawater in the model. Moreover, a short-term simulation estimated that most 3H
and 137Cs flowed to the ocean rather than remaining in the lake.
Based on calculations over the past 50 years, a peak of 137Cs in
sediment was in 1963, when the maximum 137Cs fallout was observed.
The calculation showed a rapid decrease after that peak, however, the field
measurement data gradually declined. This suggested that the process by which 137Cs
accumulated from the watershed to the lake was actually slower in the field
than in the model calculations. The model may be successfully applied to a
variety of different environmental situations as a generic tool for evaluating
the concentration and migration of 3H and 137Cs in a
brackish lake.</p>
</p> 相似文献
4.
Saad Ali Khan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(1):3-6
The sorption of long-lived radionuclides of cesium, strontium and cobalt (134Cs, 85Sr and 60Co) on bentonite under various experimental conditions, such as contact time, pH, sorbent and sorbate concentrations have been studied. The uptake of Cs and Sr was rapid and equilibrium was reached almost instantaneously in both the cases, while Co sorption was time dependent. The sorption of these nuclides increased by increasing pH. The uptake of Cs, Sr and Co increased with increasing the amount of the bentonite clay. The percentage sorption for Cs, Sr and Co decreased with increasing metal concentrations. The desorption studies with 0.01M CaCl2 and ground water at low-metal loadings on bentonite showed that about 95% of Cs, 85-90% of Sr and 97% of Co were irreversibly sorbed. These results could be helpful for nuclear waste management, for waste water effluents containing low concentrations of cesium, strontium and cobalt. 相似文献
5.
Summary The dispersion of radioactive substances in the environment following nuclear weapon tests in atmosphere since 1954 and accidents to nuclear plants, like that in Chernobyl in 1986, have allowed us to study the migration processes of some radionuclides in complex ecosystems such as lakes are. In the present paper the behavior of 137Cs and 90Sr in different compartments of the Monterosi Lake (central Italy) was assessed. The 137Cs concentration was measured in lake water as well as sediment, stream water, aquatic plant and fish samples. 90Sr concentration in water and sediments was also determined. A total inventory of 4206±76 Bq . m-2 and 958±79 Bq . m-2 (on 27/6/01) has been found for 137Cs and 90Sr, respectively. The experimental data presented here allow to calibrate theoretical models predicting the temporal trend of radionuclide concentration in similar ecosystems. Moreover, information on cesium and strontium migration processes can be extended to other pollutants having similar environmental behavior. 相似文献
6.
J. Solecki 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):357-364
Summary Results
of studies of Na+, K+ and Cs+ influence on the
adsorption of 85Sr on soil samples of the different types of
successive horizons are presented. It was proved that the adsorption isotherms
in log-log coordinates are of straight-line type and may be described by the
Freundlich equation. Monovalent cations influence the coverage degree of the
soil surface by 85Sr (most often lowering it) in the following order
K+3Na+3Cs+.
The investigation of pH influence proved its essential meaning in the process.
The plateau of surface coverage degree versus pH lies above pH 5.5 or 6.5
depending on the soil type. Generally, in the studied system, the size of 85Sr
adsorption depends on the concentration of the isotope, pH of the solution,
type of monovalent cation, and on the soil properties.</p>
</p> 相似文献
7.
Strontium
isolation from natural samples with Sr resin and subsequent determination of 90Sr</p>
</p>
Ž. Grahek K. Košutić M. Rožmarić-Mačefat 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):179-190
The
reliability of an 90Sr determination method was tested using an Sr
extraction chromatographic resin for strontium isolation. The 90Sr-content
in samples of vegetables, soil and water (obtained from Environmental
Measurement Laboratory, USA) were determined and the results were controlled by
classical methods and by using an anion-exchanger and an alcohol solution of
nitric acid for the strontium isolation. These methods were previously tested
by determining 90Sr in IAEA 326 and 327 samples of soil. It is shown
that the isolation process with Sr resin is simpler and faster than the
classical and mixed solvent anion-exchange methods. The efficiency of isolation
on a Sr column depends on the resin quantity and separation conditions; and is
the highest with a Sr column, compared to the classical and anion-exchange
methods. Experimental data and theoretical models were used to calculate the
parameters that enable the estimation of optimum dimensions of the column for
isolation. A simple relation is proposed for the calculation of breakthrough
volume, which defines the sample and eluent volumes for an optimal strontium
isolation.</p>
</p> 相似文献
8.
N. Momoshima M. Sayad M. Yamada M. Takamura H. Kawamura 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):455-460
Summary Global fallout levels of 99Tc and 137Cs of surface seawater in the Pacific Ocean were measured. The 99Tc concentrations ranged from 0.62 to 3.33 mBq. m-3and 5 of 6 samples showed less than 1 mBq. m-3except one sample taken in the Great Barrier Reef, Australia. The 137Cs concentrations ranged from 2.13 to 3.14 Bq. m-3, showing a gradual decrease in the North Pacific toward the equator and a constant level in the South Pacific. The 99Tc/137Cs activity ratios ranged from 2.5. 10-4to 2.9. 10-4, which is very close to that calculated theoretically from the fission yield. 相似文献
9.
N. W Harvey G. Shaw N. J. B. Bell 《Journal of Radioanalytical and Nuclear Chemistry》1997,226(1-2):159-173
The movement of85Sr,137Cs,54Mn and60Co in the 50 cm soil profile was studied with and without the presence of plant roots (triticum aestivum) in order to investigate the influence of roots and depth contamination upon the migration of radionuclides. The water table was maintained manually at 3 cm from the bottom. The physiochemical characteristics (Eh Fe–2, NH
4
+
, pH and moisture content) as well as the total and extractable radioactivity were investigated. In the discrete contamination, where the location of contamination varied within the soil profile (0–5, 25–30 or 45–50 cm from the top), the influence of location upon the movement of these radionuclides was also studied. It was found that the changes in the soil physicochemical characteristics influenced the mobility of the four radionuclides. The extractability of54Mn and60Co was significantly increased in the reducing region of the soil, whereas that of85Sr,137Cs was not. Plant roots excerted significant effects upon the soil characteristics, via, reducing the Eh pH and moisture content of the soil; increasing the extractability of both54Mn and60Co from the depth of 35 cm downwards. Radionuclide migration occurred via physicochemical and biological transport. The biological transport via plant roots was of particular importance for137Cs. Location of contamination had a significant influence upon the mobility of radionuclides. The migration of radionuclides was in the sequence of contamination in middle>bottom>top. The degree of the influence varied with radionuclides concemed. In the top layer contamination, the rank of the migration from the contamination layers, on the other hand54Mn,60Co and137Cs were more mobile and the movement was:85Sr54Mn60Co>137Cs. In the middle and bottom contamination layers, on the other hand,54Mn and60Co and137Cs were more mobile and the movement was85Sr54Mn60Co>137Cs. The results provide evidence conceming the soil-root interaction influencing the transfer efficiency of radionuclides from below the soil surface into the human food chain. 相似文献
10.
Summary A
rapid separation of microamounts of Sr2+ from Y3+ using
HCl, 15-crown-5 (15C5) and hydrogen dicarbollylcobaltate (H+B-)
in the two-phase water - nitrobenzene extraction system was developed. The
reached separation factor a(Sr/Y) was approximately 10. 5.4</p>
__</p> 相似文献
11.
Shuddhodan P. Mishra Diwakar Tiwari Shailesh Kumar Prasad R. S. Dubey Manisha Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):191-199
Summary The
uptake of indigenously synthesized amorphous stannic and zirconium phosphate
was assessed for, one of the important fission fragment, cesium from aqueous
solutions using a radiotracer technique. A virtual increase in sorptive
concentration (from 1.0 . 10-8 to 1.0 . 10-2
mol . dm-3) and pH (from 2.4 to 10.2) and temperature
(from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate.
However, the extremely high degree of uptake of cesium on zirconium phosphate
was almost unaffected with the dilution beyond 10-5 mol .
dm-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to
323 K). Irreversible uptake occurring for these solids follow the Freundlich
adsorption isotherm and the presence of several complexing agents viz.,
sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of
cesium on zirconium phosphate but it did affect for stannic phosphate system.
Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be
neutron source having neutron flux ca. 3.2 . 106 n .
cm-2 . s-1 and associated with a nominalg-dose of ca.
1.72 Gy/h, at least for the uptake of cesium.</p>
</p> 相似文献
12.
The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni2Fe(CN)6 accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni2Fe(CN)6 are discussed. In concentrated salt solutions, the distribution coefficients of 59Fe, 60Co, 65Zn. 137Cs, 95Zr and 144Ce are determined together with those of 85Sr and 106Ru. A simple determination of 137Cs in sea water containing 59Fe, 60Co, 65Zn, 95Zr, 144Ce, 85Sr and 106Ru is described. 相似文献
13.
Summary Leach characteristics of 137Cs and 60Co radionuclides from spent mix bead ion exchange resins and both ordinary Portland cement and cement mixed with two kind
of natural sorbents (bentonite and clinoptilolite) have been studied using the International Atomic Energy's (IAEA) standard
leach method. The waste immobilization performance of low-level wastes in natural sorbent mixtures was determined. The solidification
matrix was a standard Portland cement mixed with 290-350 (kg/m3) spent mix bead exchange resins, with or without 1-10% of bentonite or/and clinoptilolite. The leaching rates from the cement-bentonite
matrix were measured after 300 days as 60Co: (1.20-9.72) . 10-5 cm/d and 137Cs: (1.00-9.22) . 10-4 cm/d. From the leaching data, the apparent diffusivity of cobalt and cesium in cement-bentonite or/and clinoptilolite matrix
with a waste load of 350 kg/m3 of spent mix bead exchange resin was calculated as 60Co: (1.0-5.9) . 10-6 cm2/d and 137Cs: (0.48-2.4) . 10-4 cm2/d. The compressive strength of these samples is determined according to the ASTM standards. 相似文献
14.
R. C. L. Figueira E. S. B. G. Saraiva I. I. L. Cunha 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(3):801-804
Methodologies for simultaneous analysis of 137Cs, 90Sr, 238Pu and 239+240Pu were developed and applied to seawater samples. 137Cs levels in Brazilian coastal seawater ranged from 0.12 to 4.7 Bq·m-3, for 90Sr from 2.0 to 8.6 Bq·m-3, for 239+240Pu from 0.8 to 4.5 mBq·m-3 and for 238Pu it was of 1.9 mBq·m-3. The artificial radioactivity levels in Brazilian seawater are typical values due to fallout deposition. 相似文献
15.
U Myint Than Than Soe Khaing San Ba Han Thida Khin Mg Myoe J. Tölgyessy 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(2):171-176
Reverse radiometric flow injection analysis was used for the simultaneous determination of60Co,131I and137Cs in model radioactive waste water. A NaI (Tl) scintillation detector coupled to a Canberra MCA was used for measuring the activity of137Cs at 662 keV,60Co at 1173 keV and 1332 keV, and131I at 364 keV. 相似文献
16.
Studies of 137Cs distribution in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements
will serve as baseline data and background reference level for Malaysia coastline. Twenty-one locations were identified along
the coastline of East Malaysia, and from each location water samples were collected at the surface of the seawater. Ten near-shore
locations were also selected and seawater was collected at three different depths. Large volumes of seawater were collected
and the co-precipitation technique was employed to concentrate cesium. A known amount of 134Cs tracer was added as yield determinant, followed by addition of copper(II) nitrate salt and a solution of potassium hexacyanoferrate(II)
trihydrate, to precipitate the total cesium. The precipitate slurry was oven dried at 60 °C for 1–2 days, finely ground and
counted using gamma-ray spectrometry. The activity of 137Cs was determined by measuring the peak area under the photopeak of the gamma-spectrum at 661 keV, which is equivalent to
gamma-intensity corrected for detection efficiency, percentage of gamma-ray abundance of the radionuclide and recovery of
134Cs tracer. There were no significant differences of 137Cs activities both in surface and bottom water samples at 95% confidence level. The activity of 137Cs (for all samples) was found to be in the range of 1.47 to 3.36 Bq/m3 and 1.69 to 3.32 Bq/m3 for Sabah and Sarawak, respectively. 相似文献
17.
The vertical migration of 85Sr, 137Cs and 131I in some arable and undisturbed single-contaminated soils was studied by gamma-spectrometry measurements under lysimetric laboratory conditions during irrigation of the soil profiles with wet atmospheric precipitation for about one year, except 131I. A new simple exponential compartment (box) model was derived, which makes it possible to calculate the migration rate constants and migration rates in the individual soil layers (vertical sections) as well as the total vertical migration rate constants and total vertical migration rates of radionuclides in the bulk soil horizon. The relaxation times of radionuclides in respective soil horizons can also be evaluated. 相似文献
18.
C. A. Kozlowski W. Walkowiak W. Pellowski J. Koziol 《Journal of Radioanalytical and Nuclear Chemistry》2002,253(3):389-394
The paper gives a short overview of application of polymer inclusion membranes (PIMs) for separation and removal of metal ions. Investigation of the selective removal of toxic metal ions, i.e. Cr(VI), Cd(II), Zn(II) from acidic chloride aqueous solutions, as well as trace radionuclides, i.e., 137Cs, 90Sr and 60Co from wastewaters using transport across polymer inclusion membranes was studied. The carriers, i.e., tri-n-octylamine for anionic metal species, as well as dibenzo-21-crown-7, tertbutyl-dibenzo-21-crown-7, and dinonylnaphtalenesulfonic acid for metal cations were incorporated into polymer inclusion membranes composed of cellulose triacetate as a support and o-nitrophenyl pentyl ether as a plasticizer. Selective transport of chromium(VI) over zinc(II) and cadmium(II) chloride complexes through PIMs was observed. Competitive transport of trace radionuclide ions, i.e., 137Cs, 90Sr, and 60Co from NaNO3 aqueous solutions across polymer inclusion membranes containing a mixture of dinonylnaphtalenesulfonic acid, and dibenzo-21-crown-7 as the carrier provide the selectivity order Cs(I)>Sr(II)>Co(II). 相似文献
19.
I. B. Plećaš A. D. Perić J. D. Drljača A. M. Kostadinović 《Journal of Radioanalytical and Nuclear Chemistry》1992,157(1):95-104
An optimization of mortar (as matrix), improved with bentonite clay, used for immobilization of radionuclides60Co,137Cs,85Sr and54Mn, is presented. A relatively simple mathematical model is given, which permits minimization of leach rate and permeability and maximization of compressive strength. An optimal solution, based on experimental data, is given. These results will be used for a future Yugoslav radioactive waste storing center. 相似文献
20.
R. K. Singhal U. Narayanan K. Rudran 《Journal of Radioanalytical and Nuclear Chemistry》1998,238(1-2):13-20
Interception/deposition factors for airborne85Sr,131I,137Cs following atmospheric releases under simulated raining condition have been evaluated in three different type of vegetables,
i.e., beans (Phaseolus vulgaries), spinach (Spinacia oleracia) and radish (Raphamus sative). The rainfall rate in the chamber was 2 mm/h (48 mm/d). Activity was injected in the form of liquid aerosols having a size
distribution of 2.33 μm (AMAD) with a GSD of 1.98 μm into the experimental chamber containing the vegetable plants having
an arrangement to simulate rainfall. Samples were collected soon after the 30-minute rainfall period for the evaluation of
interception/deposition factor (IF/DF) of85Sr,131I,137Cs on these plants. The maximum value of the interception/deposition factor was 6.04 m3·kg−1 which was observed for131I deposition to beans plant as a whole. Interception/deposition factor values were about 4 to 7 times higher compared to dry
condition for the same of aerosols and inventories. The fraction of root activity to the activity of above soil parts has
also been evaluated to determine the transfer of activity to the roots. 相似文献