The role of vegetation in the regulation of fluxes of technogenic radionuclides at different stages after radioactive fallout

In the remote period after the radioactive fallout in the Chernobyl accident, the biological cycle of ¹³⁷Cs in pine forests of the northern forest-steppe zone and in those of Bryanskoe Polesye become essentially different. In the cleaner northern zone with dark-gray forest soil, the ¹³⁷Cs flux to the soil with litterfall exceeds its influx to the vegetation by a factor of 5; i.e., the ¹³⁷Cs cycle differs from that of stable K, the descending flux being still dominant. In the more contaminated Bryanskoe Polesye zone with podzolic illuvial-iron sandy soil, the annual ¹³⁷Cs influx to above-ground vegetation via root uptake exceeds its return to the soil with litterfall, i.e., the ¹³⁷Cs cycle approaches the biological cycle of stable K.     

Fate of radiocesium in freshwater aquatic plants and algae in the vicinity of the Fukushima Daiichi nuclear power plant

The behavior of radiocesium (¹³⁷Cs) in aquatic plants (five species) and algae (three genera) grown in either a river (one sampling point) or pond (four sampling points) in the vicinity of the Fukushima Daiichi nuclear power plant was investigated. The ¹³⁷Cs concentration of <0.45-μm fractions of water taken from the river and ponds was between 5.01 × 10^?1 and 2.98 Bq/L, while that of sediment was between 4.85 × 10³ and 5.72 × 10⁴ Bq/kg dry weight. The ratio of ¹³⁷Cs concentration of sediment/water in ponds was ~10⁴. The sediment-to-plant transfer factor (TF) [(¹³⁷Cs concentration Bq/kg dry weight_plant) × (¹³⁷Cs concentration Bq/kg dry weight_sediment)^?1] was also measured. For aquatic plants, the highest value was 5.55 for Potamogeton crispus from the river, while the lowest was 3.34 × 10^?2 for P. distinctus from a pond. There were significant differences in values between aquatic plants belonging to the same genus. The water-to-plant TF [(¹³⁷Cs concentration Bq/kg dry weight_plant) × (¹³⁷Cs concentration Bq/L_water)^?1] of filamentous algae (Spirogyra sp.) and cyanobacteria (coexisting Anabaena sp. and Microcystis sp.) were 2.39 × 10³ and 1.26 × 10³, respectively. The ¹³⁷Cs concentration of cyanobacteria in pond water was 4.87 × 10^?1 Bq/L, which was the same order of magnitude as the ¹³⁷Cs concentration of pond water. Enrichment of ¹³⁷Cs in cyanobacteria was not observed.     

Identification of processes governing long-term accumulation of 137Cs by forest trees following the Chernobyl accident

The regularities of ¹³⁷Cs distribution in trees (Pinus sylvestris and Betula pendula) growing in different types of forest ecosystems were investigated. High levels of heterogeneity of ¹³⁷Cs activity concentrations in different parts of the trees, resulting from their varied metabolism have been shown. The data obtained demonstrate a non-uniform character of ¹³⁷Cs distribution along the trunks, which can be explained by radio- nuclide fixation by the xylem vessel walls and by geometry changes along the tree trunk. It has been found that the radial distribution of ¹³⁷Cs in the tree trunk is dependent on the availability of ¹³⁷Cs in soil, which governs the transfer of this radionuclide via xylem sap and on the properties of the xylem. The accumulation of ¹³⁷Cs by trees was influenced by the vertical distribution and availability of ¹³⁷Cs in the soil as well as by the root biomass distribution in different soil horizons. A bioavailability factor, which takes into account the vertical distribution of radiocesium in soil, bioavailability of this radionuclide and distribution of root biomass in different soil horizons is proposed for comparative analyses of ¹³⁷Cs transfer from soil to trees in different types of forest ecosystems. Received: 8 February 2000 / Accepted: 1 December 2000     

Identification and expression studies of a catalase and a bifunctional catalase-peroxidase in Frankia strain R43

This study investigated the uptake of ¹³⁴Cs by Lactuca sativaL., Silybum marianumGaertn., Centaurea cyanusL., Carthamus tinctorius L. from the Asteraceae, and Beta vulgaris L. var. `Lutiancai' and Beta vulgaris L. var. `Hongtiancai' from the Chenopodiaceae grown in two widely-distributed soils (a paddy soil and a red soil) in South China. The results showed that the plants growing on the paddy soil had a relatively high yield and low [¹³⁴Cs] while those growing on the red soil showed the opposite trend. The accumulation of ¹³⁴Cs was dependent on plant species and soil types. For the paddy soil, mean values for [¹³⁴Cs] were higher for the species of the Asteraceae (ranging from 165 to 185 Bq g^–1) than for those of the Chenopodiaceae (less than 140 Bq g^–1). For the red soil, S. marianumand C. cyanus of the Asteraceae had high average concentrations of ¹³⁴Cs ranging from 340 to 400 Bq g^–1 but L. sativa and C. tinctorius from the same family had low concentrations of ¹³⁴Cs ranging from 115 to 200 Bq g^–1 on a dry weight basis. B. vulgaris L. var. `Lutiancai' and Beta vulgaris L. var. `Hongtiancai' accumulated from 120 to 231 Bq ¹³⁴Cs g^–1 of plant shoot. The transfer factor values of ¹³⁴Cs for the studied species were in general higher in red soil than in paddy soil except C. tinctorius. All plant species from the Asteraceae family growing on the paddy soil had higher transfer factors than the B. vulgaris species. S. marianum, and C. cyanus growing on the red soil had TFs >1, being much higher than the B. vulgaris species. The results therefore showed that the plant species from the Asteraceae could accumulate higher concentrations of radiocesium than the Beta vulgaristhat has previously been suggested as a candidate for phytoremediation of radiocesium contaminated soils.     

Potential for phytoextraction of137 Cs from a contaminated soil

Potential for phytoremediation of a soil contaminated with radiocesium was investigated in three phases: (1) hydroponic screening for plant species capable of accumulating elevated levels of cesium in shoots, (2) investigation of several amendments for their potential to increase the bioavailability of ¹³⁷Cs in the contaminated soil, and (3) bioaccumulation of radiocesium in shoots of plants grown in¹³⁷ Cs-contaminated soil.The bioaccumulation ratio for Cs in shoots of hydroponically grown plants ranged between 38 and 165. From solution, dicot species accumulated 2- to 4-fold more cesium in shoots than grasses. In studies investigating the bioavailability of ¹³⁷Cs in aged contaminated soil, ammonium salts were found to be the most effective desorbing agents, releasing approximately 25% of the¹³⁷ Cs. The extent of ¹³⁷Cs desorption from the soil increased with ammonium concentration up to 0.2 M. In a pot study conducted in a greenhouse, there was significant species-dependent variability in the ability to accumulate ¹³⁷Cs in the shoot from contaminated soil. The ability to accumulate ¹³⁷Cs from the soil increased in the order: reed canarygrass (Phalaris arundinacea) < Indian mustard (Brassica juncea) < tepary bean (Phaseolus acutifolius)< cabbage (B. oleracea var. capitata). It was also found that addition of NH₄NO₃ solution to the soil elicited a two- to twelve-fold increase in ¹³⁷Cs accumulation in the shoot. The greatest amount of ¹³⁷Cs (40 Bq g^-1 dw) was removed in shoots of cabbage grown in contaminated soil amended with 80 mmols NH₄NO₃ kg^-1 soil. Bioaccumulation ratios of 2–3 were obtained with the best performing plant species. These values are significantly greater than those previously reported in the literature (usually <0.1) for plants grown on aged contaminated soil. These results indicate that careful species selection along with amendments that increase the bioavailability of¹³⁷ Cs in the soil could greatly enhance the prospects for the use of plants to remediate ¹³⁷Cs-contaminated soils.     

Soil-to-plant and soil-to-grain transfer of 137Cs in field-grown maize hybrids during two contrasting seasons: assessing the phenotypic variability and its genetic component

Field-grown maize hybrids were assessed for variability in ¹³⁷Cs accumulation in vegetative parts of young and mature maize shoots and grains during 2 years with contrasting climatic conditions. Trials were carried out at different sites in the Tula region of Russia, which is characterized by a highly homogenous soil classified as Luvic Chernozem according to FAO/UNESCO, and average contamination levels of about 509–564 Bq ¹³⁷Cs kg⁻¹ soil. In the first year, 19 hybrids were tested. The two hybrids with the highest and the two with the lowest ¹³⁷Cs concentration ratios (C _r) were also tested in the second year, together with another 11 hybrids. All samples were additionally assessed for their potassium content. In both investigation periods ¹³⁷Cs accumulation in vegetative shoots and grains was found to vary up to more than twofold between hybrids. However, C _r values of those hybrids that showed a relatively low ¹³⁷Cs accumulation in the first year were not necessarily low in the second year, and the ratio between the ¹³⁷Cs C _r of low- and high-accumulating hybrids was much smaller than in the year before. In both vegetative shoots and grains the variance caused by the different years was larger than the genotypic variance, thus indicating the limits of genotype selection for this trait. Significant correlations were determined between the ⁴⁰K and ¹³⁷Cs C _r values in the same tissue, but for one hybrid indications for uncoupling of the two traits were found. Average Cs/K ratios in young shoots, mature shoots and grains were 0.06, 0.05 and 0.02, respectively, indicating tissue- and stage-specific regulation of accumulation within each plant. The findings are discussed with respect to new approaches towards a better understanding of ¹³⁷Cs accumulation and its potential reduction in plants. Katharina Schneider was deceased.     

Concentration of Radiocesium in the Wild Japanese Monkey (Macaca fuscata) over the First 15 Months after the Fukushima Daiichi Nuclear Disaster

Following the massive earthquake that struck eastern Japan on March 11, 2011, a nuclear reactor core meltdown occurred at the Fukushima Daiichi Nuclear Power Plant, operated by Tokyo Electric Power Company, and was followed by the release of large amounts of radioactive materials. The objective of this study was to measure the concentration of radiocesium ¹³⁴Cs and ¹³⁷Cs in the muscle of Japanese monkeys (Macaca fuscata) inhabiting the forest area of Fukushima City and to determine the change in concentration over time as well as the relationship with the level of soil contamination. Cesium concentrations in the muscle of monkeys captured at locations with 100,000–300,000 Bq/m² were 6,000–25,000 Bq/kg in April 2011 and decreased over 3 months to around 1,000 Bq/kg. However, the concentration increased again to 2,000–3,000 Bq/kg in some animals during and after December 2011 before returning to 1,000 Bq/kg in April 2012, after which it remained relatively constant. This pattern of change in muscle radiocesium concentration was similar to that of the change in radiocesium concentration in atmospheric fallout. Moreover, the monkeys feed on winter buds and the cambium layer of tree bark potentially containing higher concentrations of radiocesium than that in the diet during the rest of the year. The muscle radiocesium concentration in the monkeys related significantly with the level of soil contamination at the capture locations.     

Body concentration of caesium-137 in patients from Western Isles of Scotland.

OBJECTIVES--To compare caesium-137 concentrations in patients from the Western Isles Health Board, Glasgow area, and other parts of the Scottish mainland, and to investigate the source of 137Cs in patients from the Western Isles. DESIGN--Study of hypertensive patients having electrolyte concentrations measured, including 137Cs. Interview by questionnaire of island subjects about intake of foods likely to contain radiocaesium and the source of these foods. Measurement of 137Cs and 134Cs in food, urine, and vegetation. SETTING--Scottish mainland and Western Isles, 1979-86. All measurements before Chernobyl nuclear accident. PATIENTS--413 consecutive patients referred to the blood pressure unit for investigation of hypertension. 60 from the Western Isles, including 44 from North Uist; 32 from North Uist participated in the dietary analysis. MAIN OUTCOME MEASURES--Concentration of radiocaesium in the body, urine, food, and vegetation. Islanders'' consumption of local produce. RESULTS--Patients from the Western Isles had five times higher body concentrations of 137Cs (median 2.54 (interquartile range 1.25-3.73)) Bq/gK) than did patients from around Glasgow (0.47 (0.26-0.66) Bq/gK) and other parts of the Scottish mainland (0.42 (0.24-0.71) Bq/gK). Islanders often consumed local milk and mutton, but ate local fish rarely. 137Cs and 134Cs were present in coastal (21.6 Bq/kg 137Cs, 0.25 Bq/kg 134Cs) and moorland (135.9, 0.65 Bq/kg) grasses and in islanders'' urine (2.01, 0.013 Bq/l). Lower concentrations (0.336, 0.004 Bq/l), were found in the urine of Glasgow controls (p less than 0.001 for both isotopes). CONCLUSIONS--Islanders have excess body 137Cs concentrations, most of which probably comes from local milk and lamb. The radioactivity is not above the recommended safety limit. The presence of 134Cs suggests that nuclear reprocessing is the source of some of the radiocaesium.     

Age-dependent accumulation of <Superscript>137</Superscript>Cs by pike <Emphasis Type="Italic">Esox lucius</Emphasis> in the Yenisei River

Age-dependent accumulation of ¹³⁷Cs in the muscles and bodies of the pike Esox lucius (aged two to seven years) inhabiting a section of the Yenisei River polluted with artificial radionuclides has been studied. The content of ¹³⁷Cs in muscles varied from 0.5 to 7.0 Bq/kg of fresh weight. The maximum content of the radionuclide has been found in juveniles. The content of ¹³⁷Cs in pike muscles and body decreased considerably with age. The high content of ¹³⁷Cs in the muscles of juveniles is probably a consequence of their higher intensity of feeding as compared to older individuals, which is due to the intense growth of juveniles.     

The dependence of accumulation of 137Cs and 90Sr radionuclides in the forages cultivation degree of sod-podzolic soils

For prognosis of accumulation of 137Cs and 90Sr in forages harvested in radionuclide contaminated sod-podzolic soils, it is suggested to use transfer factors (TF9a) (Bq/kg)/(kBq/m2)) established not only by the content of mobile potassium (137Cs, r = -0.53) and the value of exchange acidity (90Sr, r = -0.73), but also by the index of agrochemical soil cultivation I(cd) (137Cs, r = -0.69; 90Sr, r = -0.64). The possibility of obtaining forages conforming to the state standards on the haymaking and pasture areas with high density of radioactive contamination of soils was shown by the example of "Sudkovo" collective farm. The approach is based on achievement of a high degree of cultivation (l(cd) - 0.81-1.0) due to a complex of protective measures, which resulted in a 10-fold decrease in the specific activity of 137Cs and a 4-fold decrease in the activity of 90Sr, compared to the soils with a low degree of cultivation (I(cd) - 0.41-0.60).     

Genetic variability in Scotch pine populations of the Bryansk Region radioactively contaminated in the Chernobyl accident

The method of isozyme analysis of megagametophytes is used to estimate the genetic variability in Scotch pine populations (Pinus sylvestris L.) of the Bryansk Region sites with contrasting levels of radioactive contamination (soil ¹³⁷Cs, 60 to 17 800 Bq/kg) resulting from the Chernobyl accident. All indices of genetic variability (heterozygosity, frequency of polymorphic loci, Zhivotovskii index) and frequencies of loss-of-function enzyme mutations increase with the dose absorbed by plant generative organs. The data show that high mutability is intrinsic for seeds of these pine trees, and genetic diversity in the populations is essentially conditioned by radiation exposure.     

Analysis of the genotypic variation in radiocaesium uptake from soil

Young spinach (Spinacia oleracea L., cv. Subito) and wheat (Triticum aestivum, cv. Tonic) plants were hydroponically grown in eight different nutrient solutions containing ¹³⁷Cs. Ca, Mg, K and NH₄ concentrations were varied whilst anion concentrations were equal in all solutions. The large differences in potassium content between spinach and wheat were not reflected in similar differences in ¹³⁷Cs content at any nutritive treatment.Both crops were also grown in a potted podzolic soil contaminated with radiocaesium. This experiment was conducted in a phytotron at two climatic conditions (summer and winter) which differed in day length and light intensity. Wheat plants had higher ¹³⁷Cs levels than spinach at both conditions. The ¹³⁷Cs levels furthermore decreased during development. The ¹³⁷Cs plant/soil solution concentration ratio was lower at the summer than at the winter conditions.     

Radiocaesium variability within sheep flocks: determination of 137Cs intake in free-ranging sheep

A study is described in which ¹³⁷Cs intake by free-ranging sheep was estimated at two farms in the area of west Cumbria (northwest England) which received some of the highest amounts of fallout from the Chernobyl accident within the United Kingdom. The faecal excretion of ¹³⁷Cs was estimated from faecal ¹³⁷Cs activity concentrations and the use of intraruminal controlled release devices containing Cr₂O₃ to determine faecal dry matter output. The intake of ¹³⁷Cs was estimated by assuming an apparent absorption coefficient appropriate to the herbage grazed. The methodology has the advantage that sampling of herbage representative of that ingested by study animals is not required. Caesium-137 dietary intake explained >60% of the observed variability in the ¹³⁷Cs activity concentration determined in the muscle of sheep. Resultant transfer coefficient (F _f ) values to describe the transfer of ¹³⁷Cs from the diet to muscle were in agreement with previously reported values. At one farm, there was a positive correlation between the ¹³⁷Cs activity concentration in muscle and F _f whilst at the other farm there was a negative correlation between F _f and ¹³⁷Cs dietary intake. Potential reasons for these observations are discussed. Received: 6 April 2000 / Accepted: 25 May 2000     

Land use effects on erosion and carbon storage of the Río Chimbo watershed, Ecuador

Background and aims

Soil carbon storage is an important component of global carbon cycling. Andean Andisols have high carbon content and are vulnerable to erosion because of agricultural intensification and deforestation. This study examines the effects of land use on erosion and soil carbon storage in the Río Chimbo watershed of Ecuador.

Methods

Soil carbon content, age, and erosion estimated from ¹³⁷Cs inventories was measured along an elevational transect under annual cropping, natural forest, páramo, pasture, and tree plantations.

Results

Land use, particularly annual cropping, affected ¹³⁷Cs levels in the upper soil layers, but did not have an impact on total carbon storage to a depth of 1 m. Relative erosion rates estimated from ¹³⁷Cs inventories at sites under annual cropping averaged 27 t ha^?1?y^?1 over the erosion rate of non-cultivated sites. A linear relationship was observed between soil carbon age (determined by ¹⁴C levels) and ¹³⁷Cs levels, where pasture sites had lower ¹³⁷Cs and older carbon compared to natural forest sites.

Conclusions

The effects of land use on soil loss in the Río Chimbo watershed suggest a loss and/or removal of soil carbon, particularly under annual cropping.     

Deposition of radiocesium to the soil by stemflow,throughfall and leaf-fall from beech trees

The amount of Chernobyl-derived¹³⁷Cs transferred to the soil by stemflow, throughfall (precipitation under the tree crown), and leaffall from three beeches was investigated as a function of time in the growing seasons of 1991 and 1992. Up to 70 Bq/week was deposited with the stemflow, mainly in dissolved form (<0.45 µm)=" rather=" than=" in=" particulate=" form=" (=">0.45 µm). The ratio of dissolved radiocesium to particulate radiocesium was about 10 in the stemflow. It varied considerably with time, but since these variations followed the same pattern for all three trees, they indicated a common cause to be responsible for the fractionation of radiocesium (e.g. meteorological conditions for bark weathering). A significant correlation was observed for the amount of dissolved¹³⁷Cs (in Bq) and the amount of stemflow (in liters). The¹³⁷Cs concentration in the stemflow (in Bq/1), however, decreased with increasing stemflow intensity (in Bq/week). For particulate radiocesium such correlations were not detected. Up to 5 Bq/m² per week was deposited with the throughfall from the canopy, mainly in particulate form (ratio dissolved radiocesium to particulate radiocesium = 0.34). The mean total annual amounts of¹³⁷Cs deposited to the ground (dissolved+particulate) for the three trees were: stemflow: 1991 600 Bq; 1992 460 Bq; throughfall: 1991 and 1992 100 Bq/m² each; leaffall: 1992 10 Bq/m². The data indicate that at present a substantial amount of the radiocesium in the leaves derives already from root uptake.Dedicated to Professor W. Jacobi on the occasion of his 65th birthday     

137Cs mobility in soils and its long-term effect on the external radiation exposure

To predict the external gamma-dose rate of Chernobyl-derived ¹³⁷Cs for a period of about 100 years after its deposition, the vertical distribution of radiocesium in several meadow soils in the Chernobyl area and in Germany was determined, and the corresponding residence half-times of this radionuclide in the various soil layers were evaluated using a compartment model. The resulting residence half-times were subsequently used to calculate the vertical distribution of ¹³⁷Cs in the soil as a function of time and finally to predict the external gamma-dose rates in air for these sites at various times. A regression analysis of the data obtained showed that the time dependence of the relative gamma-dose rate in air D(t) at the Chernobyl sites can be described by an exponential equation D(t) = a + b ⋅ exp(–t/c), where t is the time after deposition. For the ten German sites the best fit was obtained using the two-exponential equation D(t) = a ⋅ exp(–t/b) + c ⋅ exp(–t/d). The gamma-dose rate of ¹³⁷Cs at the Chernobyl sites decreases significantly more slowly with time than at the German sites. This means that after e.g. 30 years the mean relative gamma-dose rate at the German sites will have decreased from 100% (corresponding to an infinite plane source on a smooth surface) to 9% (95% confidence interval 8%–10%), while at the sites in the Chernobyl area it will have decreased only to 21% (20%–23%). This difference is the result of the longer residence half-times of ¹³⁷Cs in the soils at the Chernobyl sites. All results are compared with estimates from earlier studies. Received: 16 October 1996 / Accepted in revised form: 28 November 1996     

Radiocesium in mushrooms from selected locations in the Czech Republic and the Slovak Republic

In this paper, activity concentrations of radiocesium in mushrooms from various locations in the Czech Republic and the Slovak Republic in the years 2000–2004 are presented. Summary reports of Czech regulatory bodies have judged the average activity concentrations in mushrooms to be remarkably below the maximum permissible level of contamination. However, there are certain regions where radiocesium activities have approached the maximum permissible level for contamination of basic foodstuff. For example, the highest activity concentration of ¹³⁷Cs measured by gamma-spectrometry was 2,263 Bq kg⁻¹ (on a dry mass basis), in Xerocomus badius from Staré Ransko (a locality in the Czech-Moravian Highlands, Czech Republic). The highest activity concentration of ¹³⁷Cs measured in Slovakia was 966 Bq kg⁻¹ (on a dry mass basis), for Suillus luteus from Senica. For comparison, the corresponding activity concentration in a sample taken within the 30 km zone around Chernobyl was measured to be 6,000 Bq kg⁻¹ (on a dry mass basis). Our results have also demonstrated remarkably lower activity concentrations of ¹³⁷Cs in Slovakia compared to those in the Czech Republic.     

137Cs uptake in spring wheat (Triticum aestivum L.cv. Tonic) at varying K supply

Spring wheat (Triticum aestivum L. cv. Tonic) was grown for 16 days in a sandy loam soil which was contaminated with ¹³⁷Cs. The soil was fertilised with K at three rates (0,1 and 2 mmol K per 950 g dry soil) and with NO₃ ^--N at two rates (0 and 2 mmol per 950 g dry soil) in a factorial design. The ¹³⁷Cs Activity Concentration (AC) in the shoot tissue significantly reduced 8.2-fold (nil N treatment, p<0.001) and 9.3-fold (highest N dose, p<0.001) with increasing K supply. In contrast, the K application increased the ¹³⁷Cs AC in soil solution 1.7 fold (nil N treatment) or had no significant effect (highest N dose). At similar K application, the application of N increased the ¹³⁷Cs AC in the shoot compared to the control. This effect is most probably due to the increased NH₄ ⁺ concentration in soil solution which increased the ¹³⁷Cs AC in soil solution. The soil solution composition (¹³⁷Cs and K concentration) in the rhizosphere was estimated from the average soil solution composition at day 16 and solute transport calculations. The ¹³⁷Cs AC in the shoot tissue was predicted from the estimated soil solution composition in the rhizosphere and the relationship between K concentration and ¹³⁷Cs uptake derived from a nutrient solution experiment. The predictions of ¹³⁷Cs AC's in the shoot are qualitatively correct for the fertiliser effects but underestimate the observations between 1.4 and 9.9 fold.     

Radionuclide concentrations in the diet of residents in a high level natural radiation area in Iran

Concentrations of ¹³⁷Cs and ²²⁶Ra in the diet (foodstuffs and drinking water) of adult inhabitants in the high-level natural radiation area (HLNRA) of Ramsar, Iran have been determined. The annual intake of foodstuffs was estimated on the basis of their average annual consumption. Food samples collected from local markets were analyzed by means of a gamma spectrometer. The estimated annual dietary intakes of ¹³⁷Cs and ²²⁶Ra were 130Bq and 245Bq, respectively. The concentrations of natural radionuclides in food and drinking water of the residents are higher than the world average, and are correlated with the high concentration of these radionuclides in soil and water. Calculations were also made to determine the potential dose to an individual consuming such diets.     

The accumulation of the technogenic radionuclides by mushrooms in the area affected by the activity of the Krasnoyarsk mining-and-chemical industrial complex

The radionuclide content was measured in mushrooms collected in different sites situated in the zone of the radiation influence on the Mining-and-Chemical Combine at Zheleznogorsk and on the control site, near Krasnoyarsk, in 2002-2004. The analytical investigations of fruiting bodies of 12 mushroom species have revealed three gamma-emitting radionuclides: 7Be, 40K (natural) and 137Cs (artificial). It was found that only three species contain 7Be; activity concentration of 40K is not species- and site-dependent, averaging 1600 Bq/kg. All collected samples contain 137Cs, and its accumulation by mushrooms is species-specific. Suillus concentrates more 137Cs activity than other species and can be used as a bioindicator of soil contamination with radiocesium. The average activity concentration of 137Cs in Suillus granulatus collected in the sites subjected only to aerosol discharges of the MCC is more than twice higher than 137Cs content of the mushrooms collected in the control site--"Krasnoyarsk". The maximum activity concentration of 137Cs in Suillus samples collected in the sites that receive 137Cs with the flood water is an order of magnitude higher, amounting to 8624 Bq/kg. The analysis of the radionuclide distribution in a mushroom shows that 40K activity concentration is the same in caps and stems of Suillus, and 137Cs concentration in Suillus caps is 1.7-2.3 times higher than in stems. Binding of radionuclides by mushroom biomass was determined by chemical fractionation; it was found that the highest activities of 137Cs and 40K are in the exchange-adsorption fraction (56 to 71% of the total content of a radionuclide) and in the organic fraction (23 to 37%). Calculations were made for determination of the coefficients of 40K and 137Cs transfer from the soil to the fruiting body of Suillus.