Removal of226Ra(II) from uranium mining and processing effluents

The activity of¹³⁷Cs was determined in mosses and their surrounding soils in three Venezuelan cloud forests. The concentration of¹³⁷Cs in both the mosses and their respective soils were correlated with elevation (m.a.s.l.). This relationship was the result of the cloud forest effect, no direct deposition by condensation below the base of the clouds and increasing deposition of¹³⁷Cs with the density of the clouds. The ratio of the activity of¹³⁷Cs in the mosses to their surrounding soils was in general the same for sites near the top of the mountains, but the ratio at the Altos de pipe location was 3.5 times higher than that of the La Sierra mountain. This was explained by the difference in the water content of the surface and the top soil layer. It was concluded that the¹³⁷Cs measured in the mosses was from the soil effect rather than new deposition of¹³⁷Cs in the last three years.     

Determination and spatial distribution of <Superscript>137</Superscript>Cs in soils,mosses and lichens near Kavanayen,Venezuela

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.     

Seasonal changes of 137Cs in benthic plants from the southern Baltic Sea

¹³⁷Cs activity concentrations were determined in samples of macrophytes Polysiphonia fucoides (red algae) and Zostera marina (vascular plant) collected during the entire vegetation season in the Gulf of Gdańsk in the southern Baltic Sea. The measurements showed considerable seasonality of ¹³⁷Cs activity in both species; an increase of cesium concentrations was observed from spring to autumn with maximal levels 49.1 ± 1.4 Bq kg_d.w.⁻¹ (P. fucoides) and 14.5 ± 1.0 Bq kg_d.w.⁻¹ (Z. marina) in late autumn. ¹³⁷Cs concentrations observed in a given season are the result of a number of processes, the intensity of which can differ depending on external environmental conditions. The effects of these processes can differ and their directions can frequently be opposite to one another. The examined macrophytobenthic plant species could serve as bioindicators of radionuclide pollution for monitoring purposes on condition that the samples of plants are taken within a strictly defined period of the year to give comparable results and to supply realistic information about pollution levels.     

Temporal reduction of the external gamma dose rate due to 137Cs mobility in sandy beaches

In the present paper the contribution to the external gamma dose rate due to ¹³⁷Cs in soil as a function of time is presented. Sampling sites were selected along the Calabria and Basilicata Regions coastal beaches (southern part of Italy) to assess the external gamma dose rate in air, 1 m above the ground level. A convection-dispersion model, with constant parameters was used to approximate the radiocesium soil vertical migration. The model was calibrated using the initial ¹³⁷Cs activity deposition in this region (Chernobyl fallout) and ¹³⁷Cs activity concentration down the soil profile, measured 10 years later. The dispersion coefficient and the advection velocity values, were respectively: 2.17 cm² y⁻¹ and 0.32 cm y⁻¹. The Radionuclide Software Package (RSP), which uses a Monte Carlo simulation code, was used to determine the primary ¹³⁷Cs gamma dose contribution in air 1 m above the ground surface. The resulting ¹³⁷Cs external dose rate ranged from 0.42 nGy h⁻¹ in 1986, to 0.05 nGy h⁻¹ in 2007.     

Study of natural radionuclides in Karun river region

In this study the concentration of natural radionuclides has been investigated in soil and water of Karun river by using a high resolution (HPGe detector, n-type) γ-spectrometry. The concentrations range in water sample was 47.6 ± 5.6–130.8 ± 6.3, 0.0–23.4 ± 0.5 and 0–6.4 ± 2.0 Bq L⁻¹ for ⁴⁰K, ²³²Th and ²²⁶Ra respectively. For soil samples the concentration range of 275.7 ± 8.6–458.6 ± 6.8, 19.2 ± 5.35–41.1 ± 3.95 and 29.9 ± 1.53–50 ± 1.54 Bq kg⁻¹ was obtained respectively for ⁴⁰K, ²³²Th and ²³⁸U. ¹³⁷Cs was also detected in some part of the region in soil samples. The mean concentration of ¹³⁷Cs was 5.5 ± 0.6 Bq kg⁻¹. The origin of this activity is unknown. The average absorbed dose rate in outdoor air at a height of 1 m above the ground was found to be 54.3 ± 3.7 nGy h⁻¹. The results of this study indicate that the area has standard background radiation level.     

Transfer of137Cs from soil to plants in a wet montane forest in subtropical Taiwan

The distribution of¹³⁷Cs in an undisturbed, multistoried, subtropical wet montane forest ecosystem surrounding Yuanyang Lake (lake surface level ca. 1670m, in northeastern Taiwan), was investigated. The mossy forest here represents a currently-rare perhumid temperate environment in subtropical region. The radioactivity concentration of¹³⁷Cs was determined by γ-spectroscopy with a Ge(Li) detector. Although the soil is extremely acidic (pH 3.3 to 3.6) and the rainfall is high,¹³⁷Cs is evidently retained in the organic layer. The radioactivity concentration of¹³⁷Cs in surface soil ranges from 28 to 71 Bq·kg⁻¹. The concentrations of¹³⁷Cs in the ground moss layer and litter were much lower than that in the soil organic layer, this suggests that¹³⁷Cs detected is not from the newly deposited radioactive fallout. The radioactivity concentration and transfer factor (TF) of¹³⁷Cs varied with plant species. Shrubs and ferns have higher values than a coniferous tree (Taiwan cedar). The TF in this ecosystem is as high as 0.21 to 1.88. The high values of TF is attributed to the abundance of the organic matter in the forest soils. The rapid recycling of¹³⁷Cs through the soil-plant system of this undisturbed multistoried ecosystem suggests the existence of an internal cycling that help the accumulation of¹³⁷Cs in this ecosystem.     

Evaluation of 239+240Pu, 137Cs and natural 210Pb fallout in agricultural upland fields in Rokkasho, Japan

The background distributions of ^239+240Pu and ¹³⁷Cs fallout in agricultural soil were investigated in Rokkasho where Japan's first commercial nuclear fuel reprocessing plant is now being constructed. The mean inventories of ^239+240Pu and ¹³⁷Cs in three fields with non-yam-cultivation history were 116 Bq·m⁻² and 3.4 kBq·m⁻², respectively. The mean atomic ratio of ²⁴⁰Pu/²³⁹Pu for all studied fields was 0.18±0.04, and was similar to that of global fallout. The ^239+240Pu concentrations correlated very well with ¹³⁷Cs (r = 0.97) in spite of heavy disturbance of the soil, and the activity ratio of ^239+240Pu/¹³⁷Cs was 0.037±0.007, which is a typical value for global fallout. These results showed that the nuclides had similar behavior in agricultural upland fields in Rokkasho. Since ²¹⁰Pb is steadily deposited from the atmosphere to the land, this nuclide could be an index for the degree of disturbance of a field and of soil lost from the field. The ratio of excess ²¹⁰Pb inventory in the soil to the equivalent inventory of atmospheric ²¹⁰Pb deposition was 96%, and indicated that soil was not lost from the cultivated fields. This revised version was published online in July 2006 with corrections to the Cover Date.     

Anomalously high activities of <Superscript>137</Superscript>Cs in soils and vegetation on and near a diabase outcrop in La Sierra de Lema,Venezuela

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.     

Ultra low level deep water <Superscript>137</Superscript>Cs activity in the South Pacific Ocean

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.     

Depth distribution of239,240Pu and137Cs in soils of South Korea

Depth distribution of^239,240Pu and¹³⁷Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m^–2 for^239,240Pu, 1.6±1.0 Bq· ·m^–2 for²³⁸Pu and 1982.8±929.1 Bq·m^–2 for¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of^239,240Pu and¹³⁷Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of^239,240Pu and that of¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs tend to increase slightly with increasing soil depth.     

Concentrations of 137Cs and 40K in wild mushrooms collected in a forest on Noto Peninsula,Japan

A variety of wild mushrooms were collected in a forest on the Noto Peninsula, Japan, to determine the concentration of ¹³⁷Cs and ⁴⁰K. The wild mushroom species belong to the orders Agaricales and Aphyllophorales. The concentration of ¹³⁷Cs varied widely (1.4–4,100 Bq/kg dry weight) in mushrooms growing in soil. On the contrary, ¹³⁷Cs concentration levels were relatively low (1.9–20 Bq/kg-dry weight) in mushrooms growing on wood. The concentration of ⁴⁰K varied widely (12–2,400 Bq/kg-dry weight) in contrast with several previous reports that suggest relatively constant ⁴⁰K levels in mushrooms. Unusually low concentrations of ⁴⁰K were observed in a few mushroom species that had very hard fruiting bodies with peculiar shapes. The mean and median of ¹³⁷Cs concentration in the present study were similar to those previously reported for Japanese mushrooms. Among the Agaricales mushrooms, Entolomataceae and Tricholomataceae families growing in soil had the highest concentration of ¹³⁷Cs. Among the Aphyllophorales mushrooms, Gomphaceae and Ramariaceae families growing in soil also had the highest ¹³⁷Cs concentrations. The concentrations of ¹³⁷Cs and stable Cs in mushroom samples were positively correlated. The concentration ratio of ¹³⁷Cs/Cs differed between Agaricales and Aphyllophorales mushrooms. The average ¹³⁷Cs/Cs ratio in mushrooms growing in soil was similar to that calculated for the top soil (<5 cm deep) alone because the mycelia of the mushrooms were mainly distributed near the surface of the soil.     

The effect of sorption properties of soil minerals on the vertical migration rate of cesium in soil

The vertical distribution of¹³⁷Cs is shown for two types of soil: silly loamy “supposed” soil and silly lessive one, slightly eroded, occuring in the vicinity of Lublin (Eastern Poland). Based on the distribution data the vertical migration rates of¹³⁷Cs are calculated for both soils. These rates are found to be 0.045 and 0.3 cm/year respectively. The percent contribution of¹³⁷Cs originating from the damaged reactor in Chernobyl is also calculated. The kinetics of cesium adsorption and its adsorption isotherms on minerals separated from the tested soils are also studied. The sorption of Cs on soil minerals markedly affects the migration rate of¹³⁷Cs in soil. The experimental results indicate that, among the extracted mineral fractions, the largest adsorption takes place on marls from the silly loamy soil. This work is supplemented by results of a physicochemical analysis of the studied soils.     

Contribution to the external gamma dose rate from <Superscript>137</Superscript>Cs and <Superscript>40</Superscript>K activity concentrations determined in the vertical profile of sandy beaches

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.     

Measurement of 137Cs in the soil in Korea by low-level background gamma-ray spectrometer

¹³⁷Cs was measured in soil samples collected in Korea from 2006 to 2008 using a low-level background gamma-ray spectrometer that was designed and developed by KRISS (Korea Research Institute of Standards and Science). The objectives of this study are to evaluate the newly developed low-level background gamma-ray spectrometer and, consequently, to provide information on the horizontal and vertical distribution of ¹³⁷Cs in Korean soil. ¹³⁷Cs concentrations in surface soil varied from 12.8 ± 0.9 to 108 ± 4 Bq kg^?1, and the vertical profiles of ¹³⁷Cs from the Nari basin in Ulleung Island in the East Sea/Sea of Japan and Seongsan Ilchulbong Peak, Jeju Island, showed a higher concentration in the surface layer that gradually decreased with depth. On the other hand, the ¹³⁷Cs concentration in soil samples collected from Bukhan Mountain National Park in Seoul showed a subsurface maximum and decreased with depth. The ¹³⁷Cs inventories in the soil column were calculated to be 1,830–4,360 Bq m^?2 with a mean of 2,770 Bq m^?2, which was the same order of magnitude as the global fallout inventories in the mid-latitude region of the Northern Hemisphere.     

Interception/deposition of airborne85Sr,131I, and137Cs by spinach, radish and bean plants in a tropical region during rainfall

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.     

238Pu, 239+240Pu, 241Am, 90Sr and 137Cs in mountain soil samples from the Tatra National Park (Poland)

Activity concentrations and inventory for ²³⁸Pu, ^239+240Pu, ²⁴¹Am, ⁹⁰Sr, and ¹³⁷Cs in soil from Tatra Mountains of Poland are presented. Soil samples were collected using 10 cm diameter cores down to 10 cm and sliced into 3 slices. Details of the applied procedure are described with the quality assurance program. The maximum activity concentrations found for various samples were: 1782±13 Bq/kg, 17.4±0.9 Bq/kg, 3.4±0.3 Bq/kg and 84±7 Bq/kg for ¹³⁷Cs, ^239+240Pu, ²⁴¹Am and ⁹⁰Sr, respectively. The maximum cumulated deposition of ^239+240Pu is 201±8 Bq/m². The origin of radionuclides is discussed, based mostly on the observed isotopic ratio of Pu. Significant correlations were found between ^239+240Pu, ²⁴¹Am and ¹³⁷Cs. The effective vertical migration rate seems to be in the order of: ⁹⁰Sr≫Pu>Am>Cs.     

Radioactivity in the highly contaminated area near the Chernobyl site

Field measurements of radioactivity were performed in highly contaminated areas around Chernobyl in the summer of 1990. Six radionuclides including the most dominant¹³⁷Cs have been identified in soil samples through -ray spectrometry. The relation between the -ray dose rate above the ground and the radioactivity density in soils has been investigated. The external dose from deposited radiocesium for the period of 70 years after the deposition has been evaluated to be about 5 mSv per 1 and 0.5 Ci km^–2 of¹³⁷Cs and¹³⁴Cs deposition, respectively.     

Thermal neutron cross section and resonance integral of the reaction of135Cs(n,γ)136Cs: Fundamental data for the transmutation of nuclear waste

To determine the cross sections of the¹³⁵Cs(n,γ)¹³⁶Cs reaction, a sample of¹³⁵Cs included in a “standardized solution” of¹³⁷Cs was used as a target and irradiated in a reactor. The ratio of the atom number of¹³⁵Cs to that of¹³⁷Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.     

Dose rates and seasonal variations of 238U, 232Th, 226Ra 40K and 137Cs radionuclides in soils along Thrace, Turkey

Concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs are measured in collected soil samples from various locations in the Thrace region of Turkey. The activity concentrations range from 12.82 to 101.75 Bq kg^?1 d.w. (dry weight) for ²³⁸U, from 5.16 to 73.34 Bq kg^?1 d.w. for ²³²Th, from 185.54 to 5399 Bq kg^?1 d.w. for ⁴⁰K and from 11.42 to 90.73 Bq kg^?1 d.w. for ²²⁶Ra. In addition to naturally occurring radionuclides, ¹³⁷Cs activity concentration is determined between 3.05 and 46.78 Bq kg^?1 d.w. for soil samples. Determination of the radiological hazard is achieved through calculations of the external terrestrial gamma dose rate in air (nGy h^?1) and annual effective dose rate (mSv year^?1) and the results are compared with the similar works in different countries.     

Mobilization and fractionation of137Cs in calcareous soils

Mobility of¹³⁷Cs was investigated in columns of calcareous loam and clay soils leached under river water, NH₄OAc, KCl, CaCl₂, and EDTA. Fractionation of Cs into ten sequential fractions was accomplished in the leached soils as well as in soil samples received carrier-free¹³⁷Cs and incubated for 60 d. At the end of 90 d of leaching with river water and CaCl₂, the bulk of Cs applied (>97%) was found to remain in the upper 1 cm of soil columns. On the other hand, the reduction in Cs concentration was approximately 30% with NH₄OAc, 18% with KCl, and 10 to 25% with EDTA. The major soil constituents appeared to be responsible for retaining Cs were clay, silt, and Fe oxides. The leaching consistently increased the magnitude of fractions bound to clay minerals and in most cases decreased the fractions of water soluble, exchangeable, carbonate, and organic matter.