Uptake and depuration of 131I by the edible periwinkle Littorina littorea: uptake from seawater

Uptake and depuration experiments for the edible periwinkle Littorina littorea have been performed using 131I-labelled seawater. Throughout the experimental phase the winkles were fed on unlabelled Chondrus crispus. 131I concentrations in winkles during uptake followed linear first-order kinetics with an uptake half-time of 11 days, whereas for depuration a triphasic sequence with biological half-lives of 4, 23 and 56 days was determined. In general, iodine turnover in winkles via labelled seawater appears to be slower than observed for other molluscs (2-3 days). Most of the activity prior to and after depuration is found to be in the shell, with indications that shell and soft parts accumulate and depurate 131I at a similar rate. The operculum displays the highest specific activity of all fractions with a concentration factor of 750 l kg(-1). Concentration factors for whole winkle, shell, soft parts and digestive gland are in the order of 40-60 l kg(-1), higher than the IAEA recommended CF value for iodine in molluscs of 10 l kg(-1). The 131I CF in winkles is closer to that of the conservative radionuclides 99Tc and 137Cs than the CF of the particle reactive radionuclides (239,240)Pu and 241Am.     

Characterization of ²⁴¹ Am and ¹³⁴Cs bioaccumulation in the king scallop Pecten maximus: investigation via three exposure pathways

In order to understand the bioaccumulation of ²⁴¹Am and ¹³⁴Cs in scallops living in sediments, the uptake and depuration kinetics of these two elements were investigated in the king scallop Pecten maximus exposed via seawater, food, or sediment under laboratory conditions. Generally, ²⁴¹Am accumulation was higher and its retention was stronger than ¹³⁴Cs. This was especially obvious when considering whole animals exposed through seawater with whole-body concentration factors (CF_7d) of 62 vs. 1, absorption efficiencies (A_0l) of 78 vs. 45 for seawater and biological half-lives (T_b½l) of 892 d vs. 22 d for ²⁴¹Am and ¹³⁴Cs, respectively. In contrast, following a single feeding with radiolabelled phytoplankton, the assimilation efficiency (AE) and T_b½l of ¹³⁴Cs were higher than those of ²⁴¹Am (AE: 28% vs. 20%; T_b½l: 14 d vs. 9 d). Among scallop tissues, the shells always contained the higher proportion of the total body burden of ²⁴¹Am whatever the exposure pathway. In contrast, the whole soft parts presented the major fraction of whole-body burden of ¹³⁴Cs, which was generally associated with muscular tissues. Our results showed that the two radionuclides have contrasting behaviors in scallops, in relation to their physico-chemical properties.     

Radioactivity concentrations of 40K, 134Cs, 137Cs, 90Sr, 241Am, 238Pu and 239+240Pu radionuclides in Jordanian soil samples

In November 2000, surface and core soil samples were collected from different regions of Jordan. The samples were analyzed by direct gamma spectrometry and combined radiochemical separation procedure to quantify (40)K, (134)Cs, (137)Cs, (90)Sr, (241)Am, (238)Pu and (239+240)Pu radioactivity. Concentrations (Bq.kg(-1) dry weight) have been observed to vary in the range 1.5-2.6 for (134)Cs, 2.8-11.4 for (90)Sr, and 0.13-0.48 for (241)Am, 0.016-0.062 for (238)Pu, 0.28-1.01 for (239+240)Pu and 155-543 for (40)K. The typical concentration of (137)Cs found in topsoils (0-2 cm) ranged in 7.5-576 Bq.kg(-1), dry weight. These values were greater than those observed in samples taken at greater depths (up to 32 cm). Activity ratios of (134)Cs/(137)Cs, (90)Sr/(137)Cs, (239+240)Pu/(137)Cs, (238)Pu/(137)Cs, (241)Am/(137)Cs, (239+240)Pu/(238)Pu and (241)Am /(238)Pu have mean values of 0.0049 (R=1), 0.29 (R=0.76), 0.41 (R=0.90), 0.39 (R=0.85), 0.41 (R=0.88), 7.72 (R=0.97) and 16.66 (R=0.98), respectively. The underlying concentrations were correlated and relatively higher than those reported in neighboring countries. One moss sample, as a biomonitor indicator, was measured and evaluated along with the soil samples. Its data showed higher concentrations of all measured radionuclides due to accumulations over years. The depth distribution of the fission product (137)Cs and the total deposition (Bq.m(-2)) were also studied in selected samples. Estimations of the annual effective dose equivalent due to (137)Cs-soil contamination showed values up to more than 200 microSv.     

Chernobyl radionuclides in shellfish

Radionuclides from the Chernobyl accident arrived at Monaco on 30 April, 1986. A sample of Mytilus galloprovincialis collected six days later showed near-maximum levels of most radionuclides. Monitoring continued for seven months thereafter, peak concentrations being transiently as high as 480 Bq kg⁻¹ (all soft parts, wet weight) for ¹⁰³Ru. Other radionuclides detected included ¹³²Te, ^129mTe, ¹³¹I, ¹⁰⁶Ru, ¹³⁴Cs, ¹³⁷Cs, ^110mAg, ¹⁴⁰Ba, ¹²⁵Sb, ⁹⁵Nb and ¹⁴¹Ce. Biological half-lives for elimination in this environment were generally around 10 days or longer and most elimination curves contained a number of components. Radionuclide contents of the mussels were predicted quite accurately from concentrations observed on air filters collected simultaneously, but were not satisfactorily explained relative to total radionuclide concentrations in the seawater even three days after peak air filter activities. The use of concentration factors from the literature did not improve the latter predictions. This suggests that the radionuclides were absorbed very rapidly from the fallout particles, rather than from radionuclides first solubilised from particles. Patella lusitanica specimens contained activities about 20–50 times higher than those in the mussels.     

Uptake and depuration of 131I by the edible periwinkle Littorina littorea: uptake from labelled seaweed (Chondrus crispus)

Uptake and depuration experiments of (131)I from labelled seaweed (Chondrus crispus) by the edible periwinkle Littorina littorea have been performed. Radioiodine concentrations in winkles during uptake followed first-order kinetics with an uptake half-time of 1 day, and a calculated equilibrium concentration (C(infinity)) of 21 000 Bq kg(-1) resulting in a transfer factor of 0.07 with respect to the labelled seaweed used as food. For depuration, a biphasic sequence with biological half-lives of 1 and 24 days was determined. The results suggest that in general, iodine turnover in periwinkles is slower than observed for other molluscs (monophasic biological half-lives in the order of 2-3 days). Both environmental media, food and seawater, can be significant sources of radioiodine for the winkle.     

Behaviour and transport of radionuclides in soil and vegetation of a sand dune ecosystem

A sand dune ecosystem in the vicinity of the British Nuclear Fuels reprocessing plant at Sellafield, Cumbria, UK was used to examine the spatial, temporal and depth distributions of 134Cs, 137Cs, 238Pu, 239 + 240Pu and 241Am in soil and in two species of vegetation (Festuca rubra, Ammophila arenaria). Core samples showed evidence of the accumulation of radionuclides derived mainly from sea-to-land transfer. Accumulated deposits of radioactivity (0-0.1 m) lie within the range: 1.1-3.4 Bq kg-1 (134Cs), 260-440 Bq kg-1 (137Cs), 31-40 Bq kg-1 (238Pu), 150-215 Bq kg-1 (239 + 240Pu) and 190-240 Bq kg-1 (241Am). Soil profiles showed greater activity concentrations in their deeper regions and this is attributed to leaching of radionuclides in percolating drainage water accentuated by the coarse texture, low organic matter and clay mineral content of coastal sands. Radionuclide activity concentrations in F. rubra and A. arenaria were similar, in the ranges 20-70 Bq kg-1 (137Cs), 1-5 Bq kg-1 (238Pu), 10-30 Bq kg-1 (239 + 240Pu) and 10-65 Bq kg-1 (241Am). Clear temporal and spatial variations were observed in both species of vegetation, reflecting the weather conditions antecedent to the sampling period and the influence of sea-to-land transfer. Concentration ratios (vegetation:soil) for activity concentrations in the two species were similar, in the ranges: 0.05-0.14 (137Cs), 0.025-0.097 (238Pu), 0.022-0.057 (239 + 240Pu) and 0.025-0.212 (241Am).     

Uptake and depuration of 131I from labelled diatoms (Skeletonema costatum) to the edible periwinkle (Littorina littorea)

Uptake and depuration of (131)I into winkles through consumption of the diatom Skeletonema costatum is described. The work follows on from previous studies that investigated the uptake of iodine into winkles from seawater and seaweed. Incorporation of (131)I in S. costatum from labelled seawater followed linear first-order kinetics with an uptake half-time of 0.40 days. Iodine uptake in winkles from labelled S. costatum also followed linear first-order kinetics, with a calculated equilibrium concentration (C(infinity)) of 42Bqkg(-1) and a transfer factor (TF) of 1.1x10(-4) with respect to labelled diatom food. This TF is lower than that observed for uptake of (131)I in winkles from labelled seaweed. For the depuration stage, a biphasic sequence with biological half-lives of 1.3 and 255 days was determined. The first phase is biokinetically important, given that winkles can lose two-thirds of their activity during that period. This study shows that, whilst winkles can obtain radioactive iodine from phytoplankton consumption, they do not retain the majority of that activity for very long. Hence, compared with other exposure pathways, such as uptake from seawater and macroalgae, incorporation from phytoplankton is a relatively minor exposure route.     

Pre-assessment of the speciation of 60Co, 125Sb, 137Cs and 241Am in a contaminated aquifer

A sample of contaminated groundwater was analyzed using a combination of wet techniques to obtain geochemical information on the mobile species of 60Co, 125Sb, 137Cs and 241Am. The techniques were combined in a scheme to determine the predominant character of the radionuclides in negative or positive fractions, size separation by ultrafiltration, and their association with natural organic matter (NOM). The analyses indicated that the radionuclides of interest were predominantly in the negative fraction. Most of the 60Co and 125Sb were in the small size fraction (<5000 Da), and 137Cs and 241Am were found with the larger, colloidal-sized material. Antimony-125 and 60Co were predominantly in the hydrophilic fraction, while 137Cs and 241Am were found in hydrophobic fractions. Our analysis indicated that 137Cs is found in the same fraction as the large-sized colloidal (hydrophobic) material, suggesting an association with NOM. The results suggested that 60Co and 241Am were associated with NOM, in different size fractions, suggesting that these two nuclides are bound to different sites. Finally, the 125Sb results were inconclusive, whether this nuclide is associated with NOM, or it is inorganic.     

Aspects of the uptake of radionuclides by sheep grazing on an estuarine saltmarsh. 2. Radionuclides in sheep tissues

The transfer ¹³⁷Cs, ²³⁸Pu, ^239/240Pu and ²⁴¹Am to sheep which graze a saltmarsh in the Esk estuary, 7 km south of the sellafield reprocessing plant in west Cumbria (UK), has been estimated.The concentrations of gamma-emitting radionuclides and of ²³⁸Pu, ^239/240Pu and ²⁴¹Am were measured in liver, lung, muscle, kidney and bone from saltmarsh ewes and lambs. ¹³⁷Cs concentrations in the soft tissues were similar in liver, lung and muscle but were consistently higher in kidney and much lower in bone. The highest concentration of the transuranics was found in liver.Transfer coefficients and concentration factors were calculated for both ewes and lambs. The concentration of ¹³⁷Cs in the tissues of 5-month old lambs was higher than in those of their mothers. Therefore, a higher transfer coefficient was obtained for lamb muscle (1·8 × 10^?1 d kg^?1) than for ewe muscle (6·4 × 10^?2 d kg^?1). Concentration factors were consistently higher for ¹³⁷Cs than for the transuranics.     

Artificial radionuclides in the atmosphere over Lithuania

Measurements of airborne radioactive aerosol concentration were carried out on the basis of 1-3 days samples after the Chernobyl disaster and during the period of 1992-2003. Transport of "hot" particles of different composition resulted in the high activity concentrations of (137)Cs, (238)Pu, (239,240)Pu and (241)Am in the atmosphere in Vilnius at the end of April 1986. The (240)Pu/(239)Pu atom ratio showed clear evidence of non-global plutonium originating from the Chernobyl accident in the atmosphere over Lithuania. The (240)Pu/(239)Pu atom ratio ranged from 0.14 to 0.40 in monthly samples in Vilnius in 1995-2003. An increase in activity concentration of (137)Cs by a factor of 100 (up to 300 microBq/m(3)) was found following forest fires in the Ukraine and Belarus. However, no transport of the Chernobyl plutonium was observed and the (240)Pu/(239)Pu atom ratio in samples collected during the forest fires was found to be 0.229 and 0.185, respectively. The exponential decrease in the (240)Pu/(239)Pu atom ratio from 0.30 to 0.19 (mean values) was observed in 1995-2003.     

Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average (137)Cs-inventory at the site is about 2.6 MBq/m(2) (reference date 1 May 1986). Apart from (137)Cs, the following radionuclides have been identified (their activity ratios to (137)Cs in brackets): (134)Cs (0.537), (125)Sb (0.068), (60)Co (0.0022), (154)Eu (0.016), (155)Eu (0.020), (94g)Nb (9.5E-5), (239/240)Pu (0.0088), (238)Pu (0.040), (90)Sr (0.30) and (241)Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm(2)/a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu)< Am < Eu and Sr < (Cs, Nb), for D, the following rankings have been found: (Nb, Sr, Cs) < Am < Eu, Cs相似文献   

Bioavailability of sediment-associated and low-molecular-mass species of radionuclides/trace metals to the mussel Mytilus edulis

Sediments can act as a sink for contaminants in effluents from industrial and nuclear installations or when released from dumped waste. However, contaminated sediments may also act as a potential source of radionuclides and trace metals to the water phase due to remobilisation of metals as dissolved species and resuspension of particles. The marine mussel Mytilus edulis is a filter-feeding organism that via the gills is subjected to contaminants in dissolved form and from contaminants associated to suspended particles via the digestive system. In this paper the bioavailability of sediment-associated and seawater diluted Cs, Co, Cd and Zn radioactive tracers to the filtering bivalve M. edulis has been examined. The mussels were exposed to tracers diluted in ultrafiltered (<10 kDa) seawater (Low Molecular Mass form) or to tracers associated with sediment particles from the Stepovogo Fjord at Novaya Zemlya in short-term uptake experiments, followed by 1-month depuration experiments in flow-through tanks. A toxicokinetic model was fitted to the uptake and depuration data, and the obtained parameters were used to simulate the significance of the two uptake pathways at different suspended sediment loads and sediment-seawater distribution coefficients. The results of the model simulations, assuming steady state conditions, suggest that resuspended particles from contaminated sediments can be a highly significant pathway for mussels in the order ¹⁰⁹Cd ≌ ⁶⁵Zn < ¹³⁴Cs < ⁶⁰Co. The significance increases with higher suspended sediment load and with higher K_d. Furthermore, the experimental depuration data suggest that Cs is retained longer and Co, Cd and Zn shorter by the mussels when associated with ingested sediments, than if the metals are taken up from the low molecular mass (LMM) phase.     

Estimating biological half-lifes of radionuclides in marine compartments from environmental time-series measurements

Modelling radionuclide transfers between seawater and marine species on a short time scale basis requires being able to take into account the transfer kinetics. This means (1) to implement the effect of the biological half-lives of radionuclides together with the concentration factor in the calculation of transfers and (2), to get these kinetic parameters for each element and species. Biological half-lives are usually determined from laboratory labelling experiments with the challenge to match natural environmental conditions. The present work proposes a simple model that implements the effect of kinetic parameters in the calculation of transfers. This model is also used to derive the biological half-life and the concentration factor for 137Cs from time-series measurements of environmental concentrations in seawater and in the brown alga Fucus serratus, as an example. These transfer parameters are finally used to predict the Cs activities in Fucus serratus on the English Channel shores.     

238Pu, 239,240Pu, 241Am, 90Sr and 137Cs in soils around nuclear research centre Rez, near Prague

Forty-four soil samples were taken around the nuclear research centre Rez, near Prague. The mean activity concentrations of 238Pu, 239,240Pu, 241Am, 90Sr and 137Cs in uncultivated soil were 0.010, 0.26, 0.12, 2.7 and 23 Bq.kg(-1), respectively. Contents of radionuclides in cultivated soil were lower and in forest soil higher than in uncultivated soil. The mean activity ratios of 238Pu/239,240Pu, 241Am/239,240Pu, 90Sr/239,240Pu and 239,240Pu/137Cs in uncultivated soil were 0.041, 0.47, 10.9 and 0.013, respectively. The mean activity ratios in cultivated and forest soils were close to the values given above. It follows from the results that the source of 239,240Pu, 90Sr and 137Cs in the studied area is deposition from atmospheric nuclear tests, in the case of 137Cs also deposition from Chernobyl accident. The contribution of the research centre effluents was not proved for these radionuclides. Increased activity ratio of 241Am/239,240Pu indicates the presence of 241Am in the soils studied emanating from sources other than nuclear tests. Uniform distribution of the 241Am/239,240Pu activity ratio around the nuclear research centre and the absence of an area with evidently higher activity ratio, including at sites lying in the main wind direction, suggest that the additional activity of 241Am does not originate from the nuclear research centre. The additional source might be the deposition following the Chernobyl accident.     

Uptake, retention and organ/tissue distribution of 137Cs by Japanese catfish (Silurus asotus Linnaeus)

The work describes the uptake, retention/biological elimination and organ/tissue distribution of 137Cs by freshwater Japanese catfish (Silurus asotus Linnaeus) under laboratory conditions. The fish were divided into three groups based on their size and age and reared in 137Cs-spiked water. The concentration of 137Cs in the whole body of the live fish was measured at regular intervals up to 60 days. A significant accumulation of 137Cs was found, but a steady state condition was not achieved by the end of the experiment. The bioaccumulation factors at steady state and the required time to reach steady state were estimated to be 1.55 and 255 days, 1.76 and 180 days and 1.99 and 160 days for large, medium and small size fish, respectively. To determine the effective half-life of 137Cs, the fish were transferred and reared in the non-contaminated host water. The concentration of the remaining 137Cs in the whole body of the live fish was measured up to 66 days. The average effective half-life of 137Cs in the fish species was found to be approximately 142 days for fish of all sizes. The distribution of 137Cs in different organs/tissues of the fish was determined. Accumulation of 137Cs in muscle/flesh of the fish was found to be approximately 75% of whole body accumulation. The uptake rate and the retention capability of juvenile fish were found to be higher and therefore, these were more susceptible to 137Cs than adult and old fish, and could be an important source of 137Cs in the human food chain.     

Deposition and distribution of Chernobyl fallout fission products and actinides in a Russian soil profile

In this article the distribution of fission products and actinides in a soil profile from Novo Bobovicky in Russia, which was contaminated due to the Chernobyl nuclear power plant accident, is described. The ground deposition of long-lived fission products determined by gamma-spectrometry was (recalculated to 26 April 1986) 1600 kBq (137)Cs/m(2), 900 kBq (134)Cs/m(2) and 60 kBq (125)Sb/m(2). Of these radionuclides (137)Cs shows the dominating activity at the present time. After 6.5 years 90% of the Cs and Sb activity was contained in the upper 4 cm. A (239,240)Pu ground deposition of 77.4+/-8.0 Bq/m(2) was determined by alpha-spectrometry. The (238)Pu/(239,240)Pu activity ratio of 0.30+/-0.03 and (241)Pu/(239,240)Pu activity ratio of 115+/-14 (in 1986) measured in the soil profile, indicates that the analysed Pu originates mainly from the Chernobyl accident. The average (234)U/(238)U activity ratio of 1.06+/-0.29 indicates that the uranium in this soil is dominated by naturally occurring uranium.The alpha- and beta-autoradiography revealed that the activity is mainly present in particulate form. It could further be observed that the spots containing alpha- or beta-activity originated from different particles. A comparison of alpha-autoradiography with the bulk Pu and Am activity showed that 92% of the alpha-activity was present as clearly detectable alpha-spots.The beta-active particles, located by beta-autoradiography were correlated with gamma-spectrometric measurements and contained only (137)Cs. These hot spots ranged from 0.02 to 0.15 Bq.It could be concluded that the vertical transport of (137)Cs and fuel fragments occurs mainly by movement of particles through the soil. It could also be concluded that the fuel fragments found, in this soil were depleted in respect to Cs, Sb and Eu.Comparison of the analysed (238)Pu/(239,240)Pu, (241)Pu/(239,240)Pu and (241)Am/(239,240)Pu ratios with the ratios calculated with ORIGEN-S code gave an estimate of the average burn-up of the fuel particles to be in the range of 11-12 GWd/tU.The results presented in this article are valid for this single soil profile and should not be generalised unless validated in a more rigorous study of a larger number of soil profiles.     

Accumulation of anthropogenic radionuclides in cryoconites on Alpine glaciers

Cryoconites are airborne sediments which accumulate on the surface of glaciers. In samples of cryoconites a temperate Austrian glacier high activity concentrations of anthropogenic radionuclides were found, which stem from global and Chernobyl fallouts. Radionuclides identified were ¹³⁷Cs, ¹³⁴Cs, ²³⁸Pu, ^239+240Pu, ⁹⁰Sr, ²⁴¹Am, ⁶⁰Co, ¹⁵⁴Eu, ²⁰⁷Bi, and ¹²⁵Sb.     

Retention and translocation of foliar applied 239,240Pu and 241Am, as compared to 137Cs and 85Sr, into bean plants (Phaseolus vulgaris)

Foliar transfer of 241Am, 239,240Pu, 137Cs and 85Sr was evaluated after contamination of bean plants (Phaseolus vulgaris) at the flowering development stage, by soaking their first two trifoliate leaves into contaminated solutions. Initial retentions of 241Am (27%) and 239,240Pu (37%) were higher than those of 137Cs and 85Sr (10-15%). Mean fraction of retained activity redistributed among bean organs was higher for 137Cs (20.3%) than for 239,240Pu (2.2%), 241Am (1%) or 85Sr (0.1%). Mean leaf-to-pod translocation factors (Bq kg(-1) dry weight pod/Bq kg(-1) dry weight contaminated leaves) were 5.0 x 10(-4) for 241Am, 2.7 x 10(-6) for 239,240Pu, 5.4 x 10(-2) for 137Cs and 3.6 x 10(-4) for 85Sr. Caesium was mainly recovered in pods (12.8%). Americium and strontium were uniformly redistributed among leaves, stems and pods. Plutonium showed preferential redistribution in oldest bean organs, leaves and stems, and very little redistribution in forming pods. Results for americium and plutonium were compared to those of strontium and caesium to evaluate the consistency of the attribution of behaviour of strontium to transuranium elements towards foliar transfer, based on translocation factors, as stated in two radioecological models, ECOSYS-87 and ASTRAL.     

Deposition of gamma emitters from Chernobyl accident and their transfer in lichen-soil columns

Lichen-soil column samples were taken from several locations in the Southern Finland between 1986 and 2006. Columns were divided into three parts, upper lichen, lower lichen and underlying soil, and their gamma emitting radionuclides, (134)Cs, (137)Cs, (103)Ru, (95)Zr, (106)Ru, (110m)Ag, (125)Sb and (144)Ce, were measured with gamma spectrometry. Deposition values were calculated as Bq/m(2) for each sampling site. Distribution of various radionuclides in the three compartments as a function of time was determined. Both effective and ecological half-lives of all radionuclides were calculated for upper lichen, whole lichen and whole lichen-soil column. A linear relation was derived between the physical half-lives and effective half-lives for whole lichen and for whole lichen-soil column. Reindeer meat activity concentrations of various radionuclides and ensuing radiation doses to reindeer-herding people were also estimated for a hypothetical case where a similar high radioactive pollution, as was taken place in the Southern Finland, would have occurred in the reindeer-herding areas in the Finnish Lapland.     

Accumulation and release of 241Am by a macrophyte of the Yenisei River (Elodea canadensis)

The source of radioactive contamination of the Yenisei River floodplain, including contamination with transuranic elements, is the Mining-and-Chemical Combine of the Russian Ministry of Atomic Energy, which has for many years been producing weapons-grade plutonium. Transuranic elements have been detected not only in the soil and sediment of the river but also in the biomass of aquatic plants. This work is an investigation of accumulation and release of 241Am by a submerged macrophyte of the Yenisei River (Elodea canadensis) in laboratory experiments. In 2000-2003, laboratory experiments were carried out with biomass of E. canadensis Mich. and filtered river water. The samples were collected from the Yenisei River upstream of the discharge of the Combine's radioactive effluent. The experiments showed that 241Am is accumulated by Elodea biomass: the activity concentration of 241Am can reach 3280+/-240 Bq/g, with the concentration factor for 241Am 16 600+/-2200l/kg. Results of chemical fractionation have proved that in the course of 241Am accumulation by Elodea biomass, 241Am tightly bound to biomass increases from 11% to 27% of the total 241Am in the biomass. Release of 241Am from the decaying Elodea biomass has been evaluated experimentally. By the end of the experiment (lasting up to 127 days), the Elodea plants had lost up to 65% of their initial 241Am activity and the rate of 241Am release into the water environment reached 23 Bq/day.