Competitive biosorption of thorium and uranium by Micrococcus luteus

Lichens, sampled around Chernobyl in 1990 and in Slovenia in 1992, were analyzed for radionuclides and elements, including Cs. Data were processed by Monte Carlo aided Target Transformation Factor (MCTTFA). The resulting factors indicate environmental accumulation routes. ⁴⁰K : K and ²¹⁰Pb : Pb ratios tested the procedure, showing fully mixed ⁴⁰K and K, while for ²¹⁰Pb and Pb the expected variability in specific radioactivity was confirmed. ¹³⁷Cs showed a large factor-specific variability in ¹³⁷Cs : Cs ratios. For the 1990 data, MCTTFA singled-out ¹³⁷Cs in a separate factor, suggesting that the overall behavior of ¹³⁷Cs cannot be derived from that of Cs: source (route)-related specific radioactivity makes that all individual transport-components should be taken into account.     

Assessment of gamma emitting radionuclides in the aquatic ecosystem of Kakrapar Atomic Power Station and evaluation of radiological doses to aquatic plants

During operation and maintenance of Pressurised Heavy Water Reactors (PHWRs) at Kakrapar Atomic Power Station (KAPS), low level radioactive liquid waste is generated and released to the aquatic ecosystem (Moticher lake). The silt and aquatic weed (Hydrilla verticillata) samples collected from different locations in Moticher lake were analysed for ¹³⁷Cs, ¹³⁴Cs, ⁶⁵Zn, ⁶⁰Co, ⁵⁴Mn and ⁴⁰K during 2007–2008. A wide variation in activity levels of ¹³⁷Cs, ¹³⁴Cs, ⁶⁵Zn, ⁶⁰Co, ⁵⁴Mn and ⁴⁰K in silt and weed samples were observed in aquatic system of KAPS. The activity buildup in the silt is confined to a small area in the Moticher lake. The activity levels were found to be insignificant at 1 km away from discharge point (upstream and downstream). An attempt was made to evaluate the radiological dose to aquatic weed (Hydrilla verticillata), which was found to be well within the dose limit prescribed by US DOE. The total radiological dose due to the naturally occurring radionuclide (⁴⁰K) is comparatively higher than that of other reactor released gamma emitting radionuclides.     

Soil-to-mushroom transfer of <Superscript>137</Superscript>Cs, <Superscript>40</Superscript>K,alkali–alkaline earth element and heavy metal in forest sites of Izmir,Turkey

The present work is devoted to an investigation on the soil to mushroom transfer parameters for ¹³⁷Cs and ⁴⁰K radionuclides, as well as for some stable elements and heavy metals. The results of transfer factors for ¹³⁷Cs and ⁴⁰K were within the range of 0.06–3.15 and 0.67–5.68, respectively and the most efficiently transferred radionuclide was ⁴⁰K. The TF values for ¹³⁷Cs typically conformed to a lognormal distribution, while for ⁴⁰K showed normal distribution. Statistically significant correlations between ¹³⁷Cs soil to mushroom transfer factors and agrochemical soil properties have been revealed. Although the concentration ratios varied within the species, the most efficiently transferred elements seems to have been K, followed by Rb, Zn, Cu, Cd, S, Cs and Hg.     

The distribution and behaviour of artificial radionuclides in sediments of the north Wales coast,U.K.

The distribution of¹³⁴Cs,¹³⁷Cs and²¹⁴Am in surface and core sediments from areas in north Wales has been investigated. Coastal sites show a predominance of Sellafield-derived material for all three radionuclides whereas estuarine sites show an increased proportion of Chemobyl-derived caesium present. By the use of the¹³⁴Cs/¹³⁷Cs ratio, a mean proportion of Chemobyl-derived¹³⁷Cs in surface sediments collected in 1991 fell from 34% at an estuarine site to 11% at a coastal site. In deeper sections of cores representing sedimentation dates near the Chemobyl accident, up to 90% of¹³⁷Cs at the estuarine site and 26% at the coastal site can be attributed to Chemobyl. By using the position of the Chemobyl¹³⁴Cs and¹³⁷Cs peak in the cores, sedimentation rates of 0.7 mm·a^–1 were calculated.     

Radionuclide concentrations in several seaweeds and their annual variations

To examine the radionuclide concentrations in the environment, seaweeds were collected once a year since 1976 at two different places. A marked change was observed in the number of radionuclides in seaweeds. The increase of radionuclides is attributed to contamination by radioactive fallout from Chinese nuclear explosion tests. The radionuclide concentrations were strongly dependent on the species of seaweeds. A gradual decrease of the¹³⁷Cs/⁴⁰K activity ratio was observed in spite of the input of additional¹³⁷Cs fallout from Chinese nuclear tests. This implies that the amounts of¹³⁷Cs introduced into seawater by these detonations were small in comparison with those already contained in seawater. The cesium content in seawater was estimated by using specific activities of¹³⁷Cs in seaweeds and¹³⁷Cs concentration in seawater. The results show good agreement with the reported values by direct analysis of seawater.     

Study on the Horizontal Transport of Some Radionuclides in the Wieprz River Valley

A horizontal transport of radionuclides was studied by the analysis of the radioactivity of the surface soil samples from valleys of Wieprz river and its bottom sediments. Natural gamma-isotopes (⁴⁰K, ²³⁸U and ²³²Th series) antropogenic (¹³⁴Cs and ¹³⁷Cs) and alpha-isotopes ²³⁸Pu and ^239,240Pu were measured. The different kind of bed rock and terrain configuration, influenced the radionuclide transportation from the soil to river bottom sediments. Radioactivity of the sediment samples is definitely lower than the soils. Very strong adsorption of isotopes in soil hinders their horizontal migration. Calculated ²³⁸Pu/^239,240Pu ratio is characteristic for global fallout and about 90% of the ¹³⁷Cs comes from Chernobyl.     

Distribution and circulation of radionuclides originating from fallout in a forest

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.     

Radionuclides Measurement and Assay of Soil and their Corresponding Absorbed Dose Rate in Air In Aramoko-Ekiti, Nigeria

Four radionuclides ( ¹³⁷Cs, ²³⁸U, ²³²Th and ⁴⁰K) have been analysed in soil samples collected from Aramoko-Ekiti, South West Nigeria by a sensitive gamma-ray spectroscopic system consisting of a 7.6 cm × 7.6 cm Nal(TI) scintillation detector interfaced with Canberra series 10 plus multichannel analyser. Results obtained show that the radionuclides are present in varying concentrations in the soil, except ¹³⁷Cs which was not detectable. The absorbed dose rates in the air of the location due to these radionuclides is within the UNSCEAR recommended world average value.     

Occurrence of natural radionuclides and fallout cesium-137 in dry-season agricultural land of South Western Nigeria

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.     

Concentrations of 137Cs and 40K radionuclides and some heavy metals in soil samples from the eastern part of the Main Ridge of the Flysch Carpathians

The aim of the study is to present the results of determination of radioactivity of artificial ¹³⁷Cs and natural ⁴⁰K and certain heavy metals in soil samples collected from the eastern part of the Main Ridge of Carpathians, including the Beskid Niski Mts and the Bieszczady Mts. The evaluation of level of radionuclides was based on the bulk density analysis of the soil. A valuable finding of the study was a good linear correlation between the level of ¹³⁷Cs concentration and bulk density of the soil as well as an inverse correlation between radioactivity of natural ⁴⁰K and tested soil density. This might indicate though a high competitiveness of these elements between each other. Moreover, a good correlation between the concentrations of artificial element ¹³⁷Cs and Pb has been also observed in soil samples collected from the Beskid Niski Mts. In most cases, the level of artificial ¹³⁷Cs was lower comparing to an average ¹³⁷Cs concentration established for soils in Poland.     

Determination of90Sr and137Cs in mushrooms following the Chernobyl fallout

After the Chernobyl accident high concentrations of radionuclides were found in Sweden in mushrooms and the contents of⁹⁰Sr and¹³⁷Cs were measured. The level of⁹⁰Sr was generally low and, in proportion to¹³⁷Cs, 2–3 orders of magnitude lower than in the fallut. The contents of¹³⁷Cs varied among species and extreme local variations occurred. The ratio¹³⁴Cs/¹³⁷Cs diverged from other biological samples leading to the conclusion that old fallout was involved in the uptake.     

Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Six peat cores taken from three unmodified blanket and raised bogs in Ireland were sectioned and analyzed for a range of radionuclides including¹³⁴Cs,¹³⁷Cs,²³⁸Pu,²³⁹Pu,²⁴¹Am, and²¹⁰Pb.¹³⁴Cs and¹³⁷Cs were measured by high resolution gamma-spectrometry, while the transuranium nuclides were determined after chemical separation by alpha-spectrometry.²⁴¹Pu, present on the electroplated discs together with Pu(), was measured directly by low-level liquid scintillation counting. Core chronologies were established by measuring the unsupported²¹⁰Pb component using low energy photon spectrometry (LEPS). From the resulting profiles, relaxation depths and migration rates for the above mentioned radionuclides have been determined and differences in the values of these parameters interpreted.²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu ratios have been examined carefully and are discussed in some detail. Finally, the contribution from Chernobyl to the total radiocaesium inventory in each core has been established using the¹³⁴Cs/¹³⁷Cs ratio observed in the initial fallout from Chernobyl.     

Soil-to-plant transfer of 137Cs and 40K in an Atlantic blanket bog ecosystem

The transfer of ¹³⁷Cs and ⁴⁰K from soil to vegetation was studied in an Atlantic blanket bog ecosystem along the Atlantic coast of Ireland where the dominant vegetation is a mixture of Calluna vulgaris, Eriophorum vaginatum and Sphagnum mosses. The impact of soil chemistry and nutritional status of vegetation on the uptake of both radionuclides was also examined. Cesium-137 transfer factors values ranged from 1.9 to 9.6 and accumulation of ¹³⁷Cs was higher in the leaves of C. vulgaris than in the stems. Transfer factors values for ¹³⁷Cs in both C. vulgaris and E. vaginatum were similar indicating that for the vegetation studied, uptake is not dependent on plant species. The uptake of ¹³⁷Cs in bog vegetation was found to be positively correlated with the nutrient status of vegetation, in particular the secondary nutrients, calcium and magnesium. Potassium-40 transfer factors ranged from 0.9 to 13.8 and uptake was higher in E. vaginatum than in C. vulgaris, however, unlike ¹³⁷Cs, the concentrations of ⁴⁰K within the leaves and stems of C. vulgaris were similar. The concentration of both ¹³⁷Cs and ⁴⁰K found in moss samples were in general lower than those found in vascular plants.     

Chernobyl-derived radiocesium in mosses in the Black Sea area

Radiocesium (¹³⁴Cs and¹³⁷Cs) activity levels in mosses from the Black Sea area, northern Turkey, are reported following the Chernobyl accident during the period of 1989–1991. The cesium radionuclides were detected and measured in all the samples but other longlived radionuclides such as¹⁴⁴Ce and¹⁰⁶Ru were measured in only one sample. The present data support the fact that radioactivity monitoring in mosses can be useful to determine the lasting effect of radioactive contamination.     

An intercomparison of sampling techniques for measurements of radiocaesium in upland pasture and soil

An intercomparison of sampling procedures used by five laboratories for the determination of radiocaesium in vegetation and peaty soil was carried out at two locations in Cumbria. The multiple sampling has given information on the homogeneity of the parameters studied at each location. The parameters comprise soil bulk densities, total deposition of¹³⁷Cs, deposition of¹³⁷Cs in three soil layers, biomass densities, concentrations of¹³⁷Cs in pasture, and activity ratios (¹³⁴Cs/¹³⁷Cs) in soil and vegetation. The determination of total deposition of¹³⁷Cs gave no indication of differences between the laboratories. The results from the soil profiles do indicate significant differences between laboratories. One laboratory using a coring technique observed difficulties during sampling due to compression of the soil. The coring technique should thus be avoided or applied with extreme care for the sampling of depth profiles in peaty soil. The results from the sampling of pasture show no indication of differences between the laboratories. For the parameters studied the observed variabilities across soil depths and locations range from 10% to 81% in terms of relative standard deviations. A comparison across all results at the two locations indicate a 50% higher field variability at one of the sites relative to the other.     

Biosorptive behavior of some dead biomasses in the removal of Sr(85+89) from aqueous solutions

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

Evaluation of the 153Sm-EDTMP radiochemical purity using three chromatographic methods

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

Radioisotopes of thirteen elements in intertidal coastal and estuarine sediments in the Irish Sea

A survey has been carried out of⁴⁰K,⁶⁰Co,⁹⁹Tc,¹⁰⁶Ru,¹²⁵Sb,¹²⁹I,¹³⁴Cs,¹³⁷Cs,¹⁵⁴Eu,²²⁶Ra,²²⁸Ra,²³⁷Np,²³⁸Pu,^239,240Pu,²⁴¹Pu,²⁴¹Am,²⁴²Cm, and^243,244Cm activities in sediments from the Irish Sea. Several of these radionuclides were measured independently at two separate laboratories to enable the intercomparison of the results produced. The comprehensive data set generated allows the present spatial distributions of these radionuclides in coastal sediments to be examined in relation to sediment textural characteristics and by comparison with earlier survey, enables the temporal trends in their activities to be determined. In general all artificial radionuclides showed lower activities in sediments in response to falling discharges from Sellafield and relationships with either grain size, distance from Sellafield or both. Isotope ratios were similar to cumulative weighted activity ratios rather than present day values due to sediment mixing. Pu levels supplied evidence for the lag in response of sediment deposits with increasing distance from Sellafield due to sediment transport.     

Geochemical partitioning of actinides, 137Cs and 40K in a Tyrrhenian sea sediment sample: Comparison to stable elements

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

The transfer of natural (226Ra,?232Th, 40K) and artificial (137Cs, 90Sr) radionuclides from soil to the wood of a Scots pine (Pinus sylvestris L.)

On the Stabatishke site near to Ignalina Nuclear Power Plant a near surface repository for low and intermediate-level short-lived radioactive waste is being constructed to store the waste which was produced during the decommissioning of the Ignalina Nuclear Power Plant. A possible spread of radionuclides from the near surface repository and the radiation level of expression are one at the most important aspects while evaluating the safety of the repository. The article examines the specific activity of artificial (¹³⁷Cs, ⁹⁰Sr) and natural (²²⁶Ra, ²³²Th, ⁴⁰K) radionuclides in the soil of Stabatishke site of Ignalina NPP in pinewood; the spread of these radionuclides is determined in the system “soil-tree”. The change of long term soil pollution with artificial radionuclides was estimated. This is a background soil pollution which had been there before the exploitation of the near surface waste repository. The transfer factors of natural (²²⁶Ra, ²³²Th, ⁴⁰K) and artificial (¹³⁷Cs, ⁹⁰Sr) radionuclides from the 0-to-20-cm soil layer to different annual pinewood rings were measured. After estimation of the position of pine roots in accordance to the soil vertical and the annual change of the plant biomass, the transfer factor of ¹³⁷Cs movement to different annual pinewood rings from the separate 0 to 20-cm soil layers was determined.