共查询到20条相似文献,搜索用时 31 毫秒
1.
J. J. LaBrecque J. A. Alfonso P. R. Cordoves 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):405-411
As a result of routine soil sampling to determine the 137Cs background activities country-wide in Venezuela, it was decided to further investigate El Mirador (Lookout) area at the
base of the Sierra de Lema mountain range. In April 2003 (A), soil samples were collected at eight sites on and around the
edge of the diabase outcrop to confirm that this area had anomalously high 137Cs activities. In July 2003 (B), not only soil samples were collected again, but also black mat, palm tree leaves and trunks,
fruit bushes leaves and its fruit and fern leaves. The 137Cs content was measured by high resolution gamma-ray spectroscopy by a comparative method with reference materials. The 137Cs activity values range from 16.3 to 30.8 Bq·kg-1 in the soil samples collected in July 2003, 20.7–32.1 Bq·kg−1 for the black mat, 26.3–38.4 Bq·kg−1 for the palm leaves, 16.8–31.2 Bq·kg−1 for the palm trunks and 17.6–27.3 Bq·kg−1 for the fruit bush leaves, while, the 137Cs activity values for the whole fruit were between 23.4 and 30.7 Bq·kg−1; but, the value of the 137Cs activity in the center of the fruit (the edible part) was 51.6 Bq·kg−1, and the value of the 137Cs activity for the fern leaves was 51.8 Bq·kg−1. Thus, most of the 137Cs activity values determined in the soil, black mat and vegetation samples from El Mirador (Lookout) were considered anomalously
high with respect to those found near the equator and in other areas of Venezuela. Only the center of the fruit from the Clusia grandiflora bushes and the fern leaves had high activity ratios, about a factor of three and could be considered as biomonitors that
concentrate and retain the 137Cs. Finally, these anomalously high 137Cs activities have been attributed not only to the rich organic soils, as sinks, but also due to the affect of the cloud forests. 相似文献
2.
Determination and spatial distribution of <Superscript>137</Superscript>Cs in soils,mosses and lichens near Kavanayen,Venezuela 总被引:1,自引:0,他引:1
J. J. LaBrecque P. R. Cordoves 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):401-404
The activity of 137Cs was determined in soils, mosses, lichens and other vegetation along the Caruay River and near the town of Kavanayen. The
range of values for the soils was from <1.2 Bq·kg−1 of 137Cs (our detection limit) to 14.1 Bq·kg−1. The range of 137Cs activities in the mosses ranged from 9.9 to 17.9 Bq·kg−1 with a mean value of 13.4±4 Bq·kg−1; all the moss samples were found along the river. While the 137Cs activities in the lichens ranged from 9.1 to 29.8 Bq·kg−1; the two values along the river were about three factors higher than the one near Kavanayen. It was concluded that the 137Cs activities in the soils, mosses and lichens are much higher along the river in respect to the nearby town of Kavanayen. 相似文献
3.
J. J. LaBrecque P. R. Cordoves M. A. Cordoves K. Perez D. Palacios J. A. Alfonso 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):669-674
This work presents the results of 137Cs, 40K, 232Th and 238U concentration (Bq kg−1) values in coastal marine sediments collected from 38 sites along the coastline of the island of Margarita, Venezuela. The
purpose was to determine baseline values for these radionuclides in surface marine sediments and to detect if there were any
anomalously high concentration values. Only three of the 38 sediments analyzed had measurable values above the detection limit
of 0.9 Bq kg−1 for 137Cs and the highest only being 1.4 Bq kg−1. While, the concentration (Bq kg−1) ranges for the primordial radionuclides, 40K, 232Th and 238U were as follows: 12.2–211.7, <1.5–9.8 and <4.4–20.7, respectively. These concentration ranges for the primordial radionuclides
can be considered as baseline values for surface marine sediments for areas that are considered not polluted by man or contaminated
by nature. Finally, the concentration range of 137Cs can also be employed as baseline values, which only seem to have been the result of the atmospheric testing of nuclear
weapons in the past. 相似文献
4.
I. I. L. Cunha R. C. L. Figueira R. T. Saito 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):477-482
Methodologies for analysis of anthropogenic and natural radionuclides in marine samples were developed and applied in environmental
samples. Results of systematic measurements of these radionuclides have showed that artificial radioactivity levels are in
agreement with the values from the regions not affected directly by nuclear accidents or nuclear reprocessing plant discharges
and are due to the global fallout. The average concentration of137Cs is of 1.4 Bq·m−3 in seawater, ranges from 13 to 220 mBq·kg−1 in fish, and from 0.4 to 1.8 Bq·kg−1 for sediments.90Sr levels in seawater are of 1.8 Bq·m−3 and in fish vary from 19 to 75 mBq·kg−1. Sediments present concentrations of90Sr lower than 0.8 Bq·kg−1 and for239+240Pu of 0.03 to 0.18 Bq·kg−1.210Po levels in fish range from 0.5 to 5.3 Bq·kg−1. The data generated represent reference values for our country and are used to estimate the intake levels of these radionuclides
by consuming of marine products. 相似文献
5.
Chang Woo Lee Mun Ja Kang Wanno Lee Geun Sik Choi Young Hyun Cho Hee Reyoung Kim Kun Ho Chung 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):519-522
210Po in the daily diet in Korea was analyzed and the ingestion dose from an intake of 210Po was estimated by considering the dietary habit of a Korean person. The 210Po concentrations of a leafy vegetable (0.36 Bq·kg−1 for lettuce) in the terrestrial food were higher than those of grain, whereas Chinese cabbage had a lesser 210Po concentration (0.019 Bq·kg−1). The 210Po concentration of the animal product was similar to those detected in the grain and vegetable. The 210Po concentrations in the shell and crustaceous were high from 19.1 to 33.0 Bq·kg−1, however, its value fell in the overall range of the reported values. The effective dose from 210Po for an adult from the Korean population was about 269.4 μSv·y−1. Nearly 80% of the ingestion dose from the intake of 210Po was attributed to the consumption of seafood. It suggests that the marine food ingestion is a critical pathway for natural
210Po to the Korean population. 相似文献
6.
Z. Hölgye Š. Foltánová R. Filgas 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(3):601-604
The238Pu,239,240Pu and137Cs concentrations in sediments and shore deposition samples of the Vltava river were determined.239,240Pu and137Cs concentrations in sediment samples (five locations) ranged from 19.6 to 124.8 mBq·kg−1 and from 1.8 to 28.2 Bq·kg−1, respectively. The238Pu,239,240Pu and137Cs concentrations in shore deposition samples (four locations) ranged from 2 to 16.8, from 26.8 to 477.2 mBq·kg−1, and from 1.6 to 86.3 Bq·kg−1, respectively. The superficial activity of studied radionuclides in shore deposition areas was determined and radionuclide
origin at studied locations was discussed. 相似文献
7.
Yong Yi Peng Zhou Guangshan Liu 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):157-162
The atmospheric deposition fluxes of 7Be, 210Pb and 210Po at Xiamen were measured. The samples were collected from March 2004 to April 2005 and the sampling period was one month.
The 7Be and 210Pb activity were measured using HPGe γ-spectrometer after concentration using Fe(OH)3 co-precipitation method. The 210Po was counted with an α-spectrometer after the sample was digested and spontaneous plated onto a silver planchet. At Xiamen,
the atmospheric deposition fluxes of 7Be varied between 0.11 and 2.93 Bq·m−2·d−1 and the average was 1.64 Bq·m−2·d−1; 210Pb fluxes varied between 0.04 and 0.85 Bq·m−2·d−1, and the average was 0.51 Bq·m−2·d−1; 210Po fluxes varied between 0.002 and 0.133 Bq·m−2·d−1, and the average was 0.061 Bq·m−2·d−1. There were positive correlations between the deposition fluxes of 7Be, 210Pb or 210Po and the amount of precipitation. The residence time of aerosols varied between 6.0 and 54.0 days with a mean of 27.1 days,
which were calculated by 210Po/210Pb fluxes ratios. 相似文献
8.
H. Velasco M. Rizzotto N. Merkis M. Belli U. Sansone 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):395-399
Sampling sites, located along the Calabria and Basilicata Regions coastal beaches (south of Italy), were selected to assess
the external gamma dose rate in air, 1 m above ground, and to estimate the fraction attributable to the radiocesium and radiopotassium
contents along the vertical sand profile. Mean values for the gamma dose rate were: 76±30 nGy·h−1. 137Cs and 40K deposition densities in sand samples were determined for each sampling site (mean values 0.24±0.22 kBq·m−2 and 178±88 kBq·m−2, respectively). The 137Cs external dose rate contribution was assessed using a Monte Carlo simulation code. The method gives an estimation of the
contribution to the external gamma dose rate of each sand layer along the vertical profile. The dose rate associated with
the 137Cs content in sand was 0.16±0.14 nGy·h−1. The cosmic radiation and 40K contributions to the external gamma dose rate were estimated using the UNSCEAR methodologies. The values obtained were 34±3
nGy·h−1 and 18±9 nGy·h−1, respectively. 相似文献
9.
Evaluation of <Superscript>137</Superscript>Cs soil-to-plant transfer: Natural and model experiments
D. Butkus B. Lukšienė M. Konstantinova 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):411-416
Soil and meadow grass were sampled in the whole territory of Lithuania in 1992–2000. For the laboratory experiment, spring
wheat Triticum aestivum L. “Nandu” was used because its root system type is similar to that of perennial meadow grass. The 137Cs soil-to-plant transfer factor of spring wheat was determined and the results were compared with the predicted values using
a compartment model of soil-to-plant transfer and with the results of the field experiment. The results of comparing the measured
and calculated transfer factor using the model show rather good coincidence, however, the calculated values were overestimated.
The reason for overestimation can be that the uptake rate is not influenced only by the soil-to-plant transfer. The results
of the model experiment (from 0.005 m2·kg−1 to 0.053 m2·kg−1) are close to those of the field measurements for grass (from 0.013 m2·kg−1 in 1992–1995 to 0.10 m2·kg−1 in 1999–2000). 相似文献
10.
Zigetang Lake located in the central Tibetan Plateau was selected for the purpose of understanding of recent sedimentation
rates. Based on 137Cs dating marker, the sediment rate was 0.077 cm·yr−1. The sedimentation rate was calculated to be 0.071 cm·yr−1 and 0.029 g·cm−2·yr−1 on the basis of 210Pb CIC model. 210Pb CRS model was also used for understanding of recent sedimentation change. The sediment accumulation rates for the CRS model
ranged from 0.022 to 0.038 g·cm−2·yr−1 with an irregular high value of 0.12 g·cm−2·yr−1 around 1932 at Zigetang Lake core in the past eighty years. 相似文献
11.
M. Aoyama Y. Hamajima M. Fukasawa T. Kawano S. Watanabe 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):781-785
We determined 137Cs concentrations in deep water samples of the subtropical gyre in the South Pacific collected during the BEAGLE2003 cruise.
This was done at an underground facility to achieve extremely low background γ-spectrometry, and we, therefore, obtained reliable
values of 137Cs activity in the deeper layers. 137Cs activity in the layers between 2000 and 4500 m ranged from 7 ± 4 mBq m−3 to 25 ± 11 mBq m−3. The inventory of 137Cs in the water column from 2000 m to the sea bottom was estimated to be 20 ± 8 Bq m−2 to 94 ± 41 Bq m−2 in this region. 相似文献
12.
M. Liezers O. T. FarmerIII M. L. Thomas 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):309-313
The measurement of fission product cesium isotopes 135Cs and 137Cs at low femtogram (fg) 10−15 levels in ground water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is reported. To eliminate the natural barium
isobaric interference on the cesium isotopes, in-line chromatographic separation of the cesium from barium was performed followed
by high sensitivity ICP-MS analysis. A high efficiency desolvating nebulizer system was employed to maximize ICP-MS sensitivity
~10 cps/fg. The three sigma detection limit for 135Cs was 2 fg/mL (0.1 μBq/mL) and for 137Cs 0.9 fg/mL (0.0027 Bq/mL) measured from the standard with analysis time of less than 30 min/sample. Cesium detection and
135/137 isotope ratio measurement at very low femtogram levels using this method in a spiked ground water matrix is also demonstrated. 相似文献
13.
Large volumes of surface seawater samples were collected from thirty locations in the Exclusive Economic Zone (EEZ) of the
east coast Peninsular Malaysia on June 2008 to study the activity concentrations of 137Cs. The results will serve as additional information to the existing baseline data and is very useful for monitoring fresh
input of anthropogenic radionuclide into Malaysian marine environment. In this study, the activity concentrations of 137Cs were determined using co-precipitation technique, followed by Gamma Spectrometry measurement. The mean activity concentration
of 137Cs ranged between 3.40 and 5.89 Bq/m3. Higher activity concentrations were observed at the coastal and towards the south of Peninsular Malaysia and were aligned
with the high turbidity. These may due to the rapid diffusion of 137Cs from suspended particulates and fine sediments into surface seawater. The activity concentrations of 137Cs observed in this study were slightly higher than the concentrations reported in seawater at the Straits of Malacca, Vietnam
and Philippines. This might be because the study area received more input of 137Cs that originated from global fallout and then deposited on land which later being transported subsequently into the coastal
zone due to siltation and erosion processes. It could also be attributed to the intrusion of river waters containing higher
concentrations of 137Cs. 相似文献
14.
D. Desideri M. A. Meli C. Roselli L. Feduzi 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):591-600
In various samples of Mytilus galloprovincialis, 210Po was determined by alpha-spectrometry while Mn, Fe, Ni, Cu, Zn, Cd, Sn, Hg and Pb by energy dispersive, polarised X-ray
fluorescence spectrometry (EDPXRF). The mussels of different sizes were taken from 7 sites in the central Adriatic Sea along
the Marche coastal region during the four seasons of the year. 210Po activity concentration ranged between 57 and 343 Bq·kg−1 dry weight. The concentration ranges of heavy metals (μg·g−1 dry weight) were as follows: Mn: 72.9–83.1; Fe: 45.1–754; Ni: 1.3–7.6; Cu: 17.9–156; Zn: 60.9–189; Cd: 0.6–1.0; Sn: 0.6–3.9;
Hg always <0.5; Pb: 2.0–9.0. The data obtained depend upon the site and the period of the sampling and they are also compared
with those obtained by other authors for the same organism in the Mediterranean and other Italian seas. 相似文献
15.
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
16.
Mei-Wo Yii Zal U’yun Wan Mahmood 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):819-833
This study with sampling expeditions of marine sediment, seawater and biota were performed at 30 stations within Malaysian
Exclusive Economic Zone (EEZ). A total of >400 samples were collected to determine the activity concentration of anthropogenic
radionuclides (239+240Pu, 137Cs) and their activity ratio (239+240Pu/137Cs) in sediments, seawater and biota. The purpose of this study was to determine the concentration levels for these radionuclides
and to evaluate any occurrence of radioactive contamination. Sediment cores were obtained using multicorer device, while water
samples via co-precipitation techniques and biota was purchased from local fishermen. The activity concentrations of 239+240Pu in sediment, seawater and biota were ranged 0.21–0.45 Bq/kg dry wt., 2.33–7.95 mBq/m3 and <0.008 Bq/kg fresh wt., respectively. Meanwhile, the values of 137Cs were ranged <1.00–2.71 Bq/kg dry wt. in sediment, 3.40–5.89 Bq/m3 in seawater and <0.05–0.41 Bq/kg fresh wt. in biota, respectively. Activity ratios of 239+240Pu to 137Cs obtained seem to confirm that these artificial radioactivities were mainly due to global nuclear fallout. 相似文献
17.
I. Sýkora M. Ješkovský R. Janik K. Holý M. Chudý P. P. Povinec 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):779-787
Analyses of anthropogenic and natural gamma-ray emitters in the environment require high sensitive detector systems operating
in coincidence-anticoincidence modes. Thanks to an excellent energy resolution and a high efficiency, large volume HPGe detectors
have been widely used in low-level gamma-ray spectrometry. In the present paper we discuss the characteristics of single and
coincidence (HPGe-NaI(Tl)) arrangements suitable for analysis of environmental samples containing cascade gamma-ray emitters
(e.g., 60Co), positron emitters (e.g., 22Na) and single gamma-ray emitters (e.g., 137Cs). The detectors were placed in a large volume shields consisting of iron, lead and copper layers. The reduction of background
for the single gamma-ray spectrometer is between 60 and 250, depending on the gamma-ray energy. As an improvement of the apparatus,
low detection limits for analysis of 137Cs (0.3 Bq·kg−1) and 60Co (0.1 Bq·kg−1) in environmental samples, respectively, have been obtained. 相似文献
18.
S. P. Mishra D. Tiwari S. K. Prasad R. S. Dubey M. Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(2):371-379
The role of dead biomasses viz., mango (Mangifera indica) and neem (Azadirachta indica) bark samples are assessed in the removal behavior of, one of important fission fragments, Cs(I) from aqueous solutions employing
a radiotracer technique. The batch type studies were carried out to obtain various physico-chemical data. It is to be noted
that the increase in sorptive concentration (from 1.0·10−8 to 1.0·10−2 mol·dm−3), temperature (from 298 to 328 K) and pH (2.6 to 10.3) apparently favor the uptake of Cs(I) by these two bark samples. The
concentration dependence data obeyed Freundlich adsorption isotherm and the uptake follows first order rate law. Thermodynamic
data evaluation and desorption experiments reveal the adsorption to be irreversible and endothermic in nature proceeding through
ion-exchange and surface complexation for both dead biomasses. Both bark samples showed a fairly good radiation stability
in respect of adsorption uptake of Cs(I) when irradiated with a 300 mCi (Ra-Be) neutron source having an integral neutron
flux of ∼3.85·106 n·cm−2·s−1 and associated with a nominal γ-dose of ∼1.72 Gy·h−1. 相似文献
19.
V. Prakash Y. Narayana K. Siddappa 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):367-372
The activity concentrations of natural radionuclides viz. 232Th, 226Ra and 40K were measured in soil samples of Padubidri on the coastal Karnataka, the site for the proposed coal based thermal power
station, using gamma-ray spectrometry to establish a baseline data on radioactivity levels in the environment of the region.
The activity concentration of 232Th varies in the range of 38.5–115.5 Bq·kg−1 with a mean value of 66.0 Bq·kg−1, the activity concentration of 226Ra varies in the range 35.3–72.5 Bq·kg−1 with a mean value of 53.5 Bq·kg−1 and that of 40K varies in the range of 307.5–550.9 Bq·kg−1 with a mean value of 419.3 Bq·kg−1. The radium equivalent activity varies in the range of 140.0–242.9 Bq·kg−1 with a mean value of 180.2 Bq·kg−1. The correlation between 226Ra and 40K, 232Th and 40K and 226Ra and 232Th was studied from the results of the concentration of these naturally occurring radionuclides. The calculated dose rates
in air due to these naturally occurring radionuclides varies in the range of 66.0–110.0 nGy·h−1 with a mean dose rate of 83.1 nGy·h−1. 相似文献
20.
Radioactivity of coals and fly ashes 总被引:1,自引:0,他引:1
C. Papastefanou 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(1):29-35
The level and the behavior of the naturally occurring primordial radionuclides 238U, 226Ra, 210Pb, 232Th, 228Ra and 40K in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in
Greece ranged from 117 to 435 Bq·kg−1 for 238U, from 44 to 255 Bq·kg−1 for 226Ra, from 59 to 205 Bq·kg−1 for 210Pb, from 9 to 41 Bq·kg−1 for 228Ra and from 59 to 227 Bq·kg−1 for 40K. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of
the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq·kg−1 for 238U, from 142 to 605 Bq·kg−1 for 226Ra, from 133 to 428 Bq·kg−1 for 210Pb, from 27 to 68 Bq·kg−1 for 228Ra and from 204 to 382 Bq·kg−1 for 40K. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion
process. The enrichment factors (EF) ranged from 0.60 to 0.76 for 238U, from 0.69 to 1.07 for 226Ra, from 0.57 to 0.75 for 210Pb, from 0.86 to 1.11 for 228Ra and from 0.95 to 1.10 for 40K. 相似文献