Sources and distributions of Cs, Pu, Pu radionuclides in the north-western Barents Sea

Sediment deposits are the ultimate sink for anthropogenic radionuclides entering the marine environment. The major sources of anthropogenic radionuclides to the Barents Sea are fallout from nuclear weapons tests, long range transport from other seas, and river and non-point freshwater supplies. In this study we investigated activity concentrations, ratios, and inventories of the anthropogenic radionuclides, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu in dated sediment cores collected along a north-south transect in the northwestern Barents Sea. The data were used to evaluate the influence of different sources on the derived spatial and temporal patterns of anthropogenic radionuclides in seafloor sediment deposits. Activity concentrations of ¹³⁷Cs ranged from <0.1 Bq/kg to 10.5 Bq/kg while ^239,240Pu ranged from <0.01 Bq/kg to 2.74 Bq/kg and ²³⁸Pu activity concentrations ranged from <0.01 Bq/kg to 0.22 Bq/kg. Total inventories of ¹³⁷Cs ranged from 29.5 ± 1.5 Bq/m² to 152.7 ± 5.6 Bq/m² and for ^239,240Pu inventories (6 sediment layers only) ranged from 9.5 ± 0.3 Bq/m² to 29.7 ± 0.4 Bq/m². Source contributions varied among stations and between the investigated radionuclides. The ²³⁸Pu/^239,240Pu ratios up to 0.18 indicate discharges from nuclear fuel reprocessing plants as a main contributor of plutonium. Based on ²³⁸Pu/^239,240Pu ratio, it was calculated that up to 19-27% of plutonium is supplied from sources other than atmospheric global fallout. Taking into account Atlantic current flow trajectories and that both activity concentrations and inventories of plutonium negatively correlate with latitude, Sellafield is a major source for the Barents Sea. Concentrations and inventories of ¹³⁷Cs correlate positively with latitude and negatively with distance from the Svalbard archipelago. The ¹³⁷Cs concentrations are highest in an area of intensive melting of sea ice formed along the Siberian coast. Thus, sea ice and supplies from Svalbard may be important source of ¹³⁷Cs to the Barents Sea seafloor.     

Migration of Cs in tributaries,lake water and sediment of Lago Maggiore (Italy,Switzerland) – analysis and comparison with Lago di Lugano and other lakes

This paper describes the behaviour of ¹³⁷Cs in Lago Maggiore and other pre-alpine lakes as a consequence of atmospheric nuclear weapons testing fallout and the fallout from the nuclear accident in Chernobyl. It presents data on the ¹³⁷Cs distribution in tributaries, lake water, bottom sediments and reveals the role of ¹³⁷Cs as a marker of the sedimentation processes. The run-off of ¹³⁷Cs from the watershed to the lake is described with a simple compartment model. Measurements of the activity concentration of ¹³⁷Cs in sediments are compared with the output of a model (diffusion–convection type) which describes the input of ¹³⁷Cs into and its vertical distribution within the sediment. Varying sedimentation rates (0.05–0.90 g (cm² y)⁻¹) in Lago Maggiore are compared with data of other authors. Sedimentation rates and total distribution coefficients (of about 10⁵ L kg⁻¹) in Lago Maggiore are discussed and compared with those of Lago di Lugano, Lake Constance, and Lake Vorsee.     

Application of the ERICA Assessment Tool to freshwater biota in Finland

In recent years there has been growing international interest in the assessment of doses and risks from ionising contaminants to biota. In this study the ERICA Tool, developed within the EC 6th Framework Programme, was applied to estimate incremental dose rates to biota in freshwater ecosystems in Finland mainly resulting from exposure to the Chernobyl-derived radionuclides ¹³⁷Cs, ¹³⁴Cs and ⁹⁰Sr. Data sets consisting of measured activity concentrations in fish, aquatic plants, lake water and sediment for three selected lakes located in a region with high ¹³⁷Cs deposition were applied in the assessment. The dose rates to most species studied were clearly below the screening level of 10 μGy h⁻¹, indicating no significant impact of the Chernobyl fallout on these species. However, the possibility of higher dose rates to certain species living on or in the bottom sediment cannot be excluded based on this assessment.     

Cesium-137 contamination of oak (Quercus petrae Liebl.) from sub-mediterranean zone in South Bulgaria

This study focuses on the cesium-137 (¹³⁷Cs) contamination in grass and in different compartments of oak trees growing in ecosystems, located in the zone with sub-mediterranean climate in South Bulgaria, characterized with high summer temperatures, low precipitation and often periods of drought. In 2008, three experimental sites - PP1, PP2, PP3 - were sampled in oak ecosystems from Maleshevska Mountain at 900 m above sea level. Samples from grass species and oak tree leaves, branches with different diameter, wood disks and bark were analyzed for ¹³⁷Cs activity with γ-spectrometry. The soil-to-plant transfer factor (TF) values for ¹³⁷Cs were estimated differentiating different tree compartments. Our findings showed relatively high activity concentrations of ¹³⁷Cs in oak trees even 22 years after the Chernobyl accident. The grass under oak was less contaminated compared with the oak trees. The different organs of oak trees could be distinguished according to the ¹³⁷Cs contamination as follows: bark > branches (d < 1 cm) > leaves > branches (d > 3 cm) > wood. The relatively higher contamination of bark compared with the new-formed biomass suggested that a significant part of ¹³⁷Cs was accumulated as a result of direct adsorption at the time of the main contamination event. The TF values obtained and the presence of ¹³⁷Cs in the branches, leaves and in the wood formed after 1986 confirmed that 22 years after the contamination, the main mechanism of ¹³⁷Cs entrance in tree biomass was the root uptake.     

Establishment of control site baseline data for erosion studies using radionuclides: a case study in East Slovenia

The aim of the present study was to establish a reference site and its soil characteristics for use of fallout radionuclides in erosion studies in Slovenia. Prior to this study, no reference site and baseline data existed for Slovenia for this purpose. In the agricultural area of Gori?ko in East Slovenia, an undisturbed forest situated in Šalamenci (46°44’N, 16°7’E), was selected to establish the inventory value of fallout ¹³⁷Cs and to establish a baseline level of multi-elemental fingerprint (major, minor, trace elements including heavy metals) and naturally occurring radionuclides in soils. A total of 20 soil profiles were collected at four 10 cm depth increments for evaluation of baseline level of ¹³⁷Cs inventory. An exponential distribution for ¹³⁷Cs was found and the baseline level inventory was established at 7300 ± 2500 Bq m⁻² with a coefficient of variation of 34%. Of this mean present-day inventory, approximately 45% is due to the Chernobyl contribution.The physical degradation of soils through erosion is linked with biochemical degradation. This study introduces an approach to establishment of the naturally occurring radionuclide and elemental fingerprints baseline levels at a reference site which can provide comparative data to those from neighbouring agricultural fields for assessment of soil redistribution magnitude using fallout radionuclides. In addition, this information will be used to determine the impact of soil erosion processes and agricultural practices on soil quality and redistribution within agricultural landscapes in Slovenia.     

Time-dependency of the Cs contamination of wild boar from a region in Southern Germany in the years 1998 to 2008

Following the Chernobyl accident, ¹³⁷Cs contamination levels of wild boar in some districts of Southern Germany are still exceeding thousands of Bq kg⁻¹. While the long term ¹³⁷Cs concentration in forest plants, mushrooms, and roe deer meat has decreased significantly, for wild boar it has remained constant during the last decade. Between 1998 and 2008, we analysed the muscle meat of 656 wild boars shot in the district (“Landkreis”) Ravensburg. The ¹³⁷Cs activity concentration showed considerable variability from less than 5 up to 8266 Bq kg⁻¹ and it followed a seasonal pattern, which is attributed to changes in dietary habits, fodder availability, meteorological conditions and specific behaviour of ¹³⁷Cs in wild boar organism. T_ag values for wild boars from the district Ravensburg varied from 0.008 to 0.062 m² kg⁻¹ during 2000–2008.     

Accumulation of Cs in puddle sediments within urban ecosystem

The role of puddle sediments as a final depot of ¹³⁷Cs horizontal migration within the urban landscape is studied using the example of Ekaterinburg city, Russia. Radioactive contamination in the city appeared due to fallout after atmospheric testing of nuclear weapons and nuclear accidents. Contamination density of ¹³⁷Cs in the region was assessed from archive data to be about 5.1 kBq/m², of which the maximum activity concentration (<30 Bq/kg) is associated with the upper 15 cm soil layer. Results of the survey reported here indicate a mean ¹³⁷Cs activity concentration in puddle sediments of 80 Bq/kg, with a maximum value of 540 Bq/kg. It is estimated that horizontal migration has led to about a fourfold concentration of ¹³⁷Cs in puddle sediments.     

Cs in a raised bog in central Sweden

The vertical distribution of ¹³⁷Cs activity in peat soil profiles and ¹³⁷Cs activity concentration in plants of various species was studied in samples collected at two sites on a raised bog in central Sweden. One site (open bog) was in an area with no trees and only a few sparsely growing plant species, while the other (low pine) was less than 100 m from the open bog site and had slowly growing Scots pine, a field layer dominated by some ericaceous plants and ground well-covered by plants. The plant samples were collected in 2004–2007 and were compared with samples collected in 1989 from the same open bog and low pine sites. Ground deposition of ¹³⁷Cs in 2005 was similar at both sites, 23?000 Bq m⁻². In the open bog peat profile it seems to be an upward transport of caesium since a clear peak of ¹³⁷Cs activity was found in the uppermost 1–4 cm of Sphagnum layers, whereas at the low pine site ¹³⁷Cs was mainly found in deeper (10–12 cm) layers. The migration rate was 0.57 cm yr⁻¹ at the open bog site and the migration centre of ¹³⁷Cs was at a depth of 10.7, while the rate at the low pine site was 0.78 cm yr⁻¹ and the migration centre was at 14.9 cm. Heather (Calluna vulgaris) was the plant species with the highest ¹³⁷Cs activity concentrations at both sites, 43.5 k Bq⁻¹ DM in 1989 decreasing to 20.4 in 2004–2007 on open bog and 22.3 k Bq kg⁻¹ DM in 1989 decreasing to 11.2 k Bq⁻¹ DM by the period 2004–2007 on the low pine site. ¹³⁷Cs transfer factors in plants varied between 0.88 and 1.35 on the open bog and between 0.48 and 0.69 m² kg⁻¹ DM at the low pine site.     

Transfer parameter values in temperate forest ecosystems: a review

Compared to agricultural lands, forests are complex ecosystems as they can involve diverse plant species associations, several vegetative strata (overstorey, shrubs, herbaceous and other annual plant layer) and multi-layered soil profiles (forest floor, hemi-organic and mineral layers). A high degree of variability is thus generally observed in radionuclide transfers and redistribution patterns in contaminated forests. In the long term, the soil compartment represents the major reservoir of radionuclides which can give rise to long-term plant and hence food contamination. For practical reasons, the contamination of various specific forest products has commonly been quantified using the aggregated transfer factor (T_ag in m² kg⁻¹) which integrates various environmental parameters including soil and plant type, root distribution as well as nature and vertical distribution of the deposits. Long lasting availability of some radionuclides was shown to be the source of much higher transfer in forest ecosystems than in agricultural lands. This study aimed at reviewing the most relevant quantitative information on radionuclide transfers to forest biota including trees, understorey vegetation, mushrooms, berries and game animals. For both radiocaesium and radiostrontium in trees, the order of magnitude of mean T_ag values was 10⁻³ m² kg⁻¹ (dry weight). Tree foliage was usually 2–12 times more contaminated than trunk wood. Maximum contamination of tree components with radiocaesium was associated with (semi-)hydromorphic areas with thick humus layers. The transfer of radionuclides to mushrooms and berries is high, in comparison with foodstuffs grown in agricultural systems. Concerning caesium uptake by mushrooms, the transfer is characterized by a very large variability of T_ag, from 10⁻³ to 10¹ m² kg⁻¹ (dry weight). For berries, typical values are around 0.01–0.1 m² kg⁻¹ (dry weight). Transfer of radioactive caesium to game animals and reindeer and the rate of activity reduction, quantified as an ecological half-life, reflect the soil and pasture conditions at individual locations. Forests in temperate and boreal regions differ with respect to soil type and vegetation, and a faster decline of muscle activity concentrations in deer occurs in the temperate zone. However, in wild boar the caesium activity concentration shows no decline because of its special feeding habits. In the late phase, i.e. at least a few months since the external radionuclide contamination on feed plants has been removed, a T_ag value of 0.01 m² kg⁻¹ (fresh weight) is common for ¹³⁷Cs in the muscles of adult moose and terrestrial birds living in boreal forests, and 0.03 m² kg⁻¹ (fresh weight) for arctic hare. Radiocaesium concentrations in reindeer muscle in winter may exceed the summer content by a factor of more than two, the mean T_ag values for winter ranging from 0.02 to 0.8 m² kg⁻¹ (fresh weight), and in summer from 0.04 to 0.4 m² kg⁻¹. The highest values are found in the year of initial contamination, followed by a gradual reduction. In waterfowl a relatively fast decline in uptake of ¹³⁷Cs has been found, with T_ag values changing from 0.01 to 0.002 m² kg⁻¹ (fresh weight) in the three years after the contaminating event, the rate being determined by the dynamics of ¹³⁷Cs in aquatic ecosystems.     

Foliar and root uptake of 134Cs, 85Sr and 65Zn in processing tomato plants (Lycopersicon esculentum Mill.)

Rice is a staple food in Japan and other Asian countries, and the soil-to-plant transfer factor of 137Cs released into the environment is an important parameter for estimating the internal radiation dose from food ingestion. Soil and rice grain samples were collected from 20 paddy fields throughout Aomori Prefecture, Japan in 1996 and 1997, and soil-to-polished rice transfer factors were determined. The concentrations of 137Cs, derived from fallout depositions, stable Cs and K in paddy soils were 2.5-21 Bq kg(-1), 1.2-5.3 and 5000-13000 mg kg(-1), respectively. The ranges of 137Cs, stable Cs and K concentration in polished rice were 2.5-85 mBq kg(-1) dry wt., 0.0005-0.0065 and 580-910 mg kg(-1) dry wt., respectively. The geometric mean of soil-to-polished rice transfer factor of 137Cs was 0.0016, and its 95% confidence interval was 0.00021-0.012. The transfer factor of 137Cs was approximately 3 times higher than that of stable Cs at 0.00056, and they were well correlated. This implied that fallout 137Cs, mostly deposited up to the 1980s, is more mobile and more easily absorbed by plants than stable Cs in the soil, although the soil-to-plant transfer of stable Cs can be used for predicting the long-term transfer of 137Cs. The transfer factors of both 137Cs and stable Cs decreased with increasing K concentration in the soil. This suggests that K in the soil was a competitive factor for the transfers of both 137Cs and stable Cs from soil-to-polished rice. However, the transfer factors of 137Cs and stable Cs were independent of the amount of organic materials in soils.     

Temporal and spatial distribution of Cs in Eastern Mediterranean Sea. Horizontal and vertical dispersion in two regions

Caesium-137 activity concentration in the water columns of the Gulf of Patras (Central Greece) and the North-Eastern Aegean Sea (easterward to Lemnos Island) was investigated in selected sampling stations during the period September 2004–June 2006. The methodology followed was based on the sorption of caesium (Cs) on cotton wound cartridge filters impregnated by Cu₂[Fe(CN)₆] via in-situ pumping. In terms of the horizontal and vertical records, the activity concentrations of ¹³⁷Cs in the Gulf of Patras ranged between 1.2 and 6.7 Bq m⁻³, depending on the sampling period and the prevailing physicochemical regime at the sampling station. The general pattern of the decreased activity concentrations of ¹³⁷Cs with increasing depth was reversed in the Gulf of Patras during the cold period attributed to the prevailing advective processes of the area. The activity concentrations of ¹³⁷Cs in the North-Eastern Aegean Sea ranged from 2.6 to 12.8 Bq m⁻³, whereas significant stratified curves were observed during the warm period and also, in one station during the cold period. In terms of temporal variation, the discharges in the Gulf of Patras resulted in enhanced levels of ¹³⁷Cs, whereas in the North Aegean Sea the incoming water masses form the Black Sea had an apparent influence throughout the year by increasing the ¹³⁷Cs levels, hence presenting a weak seasonal variation. Comparing the two studied areas, one could say that the North Aegean Sea, as an open sea environment, presented higher concentrations due to the influence of the Black Sea water masses. The estimated inventories of ¹³⁷Cs in the Gulf of Patras ranged 0.25 ± 0.03–0.79 ± 0.03 kBq m⁻², whereas in the North-Eastern Aegean Sea they ranged 0.33 ± 0.02–0.92 ± 0.03 kBq m⁻².     

Global transport rates of Cs and Pu originating from the Nagasaki A-bomb in 1945 as determined from analysis of Canadian Arctic ice cores

Recent advancements in analytical technology make it possible for artificial radionuclides released from nuclear explosions to be detected in Arctic ice core layers. The fission product, ¹³⁷Cs, and the unexpended fission material, ^239+240Pu, originating from the Nagasaki A-bomb of August 1945, were measured by collecting 10 ice cores on the Agassiz ice cap, Ellesmere Island, Canada. The deposition rates were 0·020 mBq cm^-2 for ¹³⁷Cs and 0·0016 mBq cm^-2 for ^239+240Pu, originating from Nagasaki. Assuming the radionuclides, excluding the amount fissioned from the explosion and deposi-ted as local fallout, are deposited evenly throughout the Northern Hemisphere, 67% of the expected amount of ¹³⁷Cs reached the Arctic while 1·1% of ^239+240Pu reached the Arctic. The results suggest that different transport mechanisms exist for various contaminants in the global transport system.     

Soil redistribution rate and its relationship with soil organic carbon and total nitrogen using Cs technique in a cultivated complex hillslope in western Iran

The spatial pattern of soil redistribution rate was investigated using cesium-137 (¹³⁷Cs) within a cultivated complex hillslope in western Iran. The relationship between soil redistribution rate and soil organic carbon and total nitrogen pattern were studied using co-regionalization analysis. Ninety-one soil cores were sampled for ¹³⁷Cs, total nitrogen, and soil organic carbon measurements. The simplified mass balance model estimated a gross erosion rate of 29.8 t ha⁻¹ yr⁻¹ and a net soil deposition rate of 21.8 t ha⁻¹ yr⁻¹; hence, a net soil loss rate of 8 t ha⁻¹ yr⁻¹. This magnitude of soil erosion rate is higher than the acceptable rate in semiarid regions. Co-regionalization analysis and co-dispersive coefficients among the selected variables showed that only a small fraction of the variability in total nitrogen and soil organic carbon could be explained by soil redistribution and that the remaining might be the result of different management practices by local farmers.     

Natural and artificial radioactivity determination of some medicinal plants

Several medicinal plants used in Italy were analysed to determine natural and artificial radioactivity in those parts (leaves, fruits, seeds, roots, peduncles, flowers, barks, berries, thallus) used generally as remedies. The radionuclides were determined by alpha (²³⁸U, ²¹⁰Po) and gamma (²¹⁴Pb-Bi, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs) spectrometry. ²³⁸U ranged between <0.1 and 7.32 Bq kg_dry⁻¹; ²¹⁰Po between <0.1 and 30.3 Bq kg_dry⁻¹; ²¹⁴Pb-²¹⁴Bi between <0.3 and 16.6 Bq kg_dry⁻¹; ²¹⁰Pb between <3 and 58.3 Bq kg_dry⁻¹; ⁴⁰K between 66.2 and 3582.0 Bq kg_dry⁻¹; ¹³⁷Cs between <0.3 and 10.7 Bq kg_dry⁻¹. The percentage of ²¹⁰Po extraction in infusion and decoction was also determined; the arithmetical mean value of percentage of ²¹⁰Po extraction resulted 20.7 ± 7.5.     

Plutonium as a chronomarker in Australian and New Zealand sediments: a comparison with Cs

The construction of high resolution chronologies of sediment profiles corresponding to the last 50-100 years usually entails the measurement of fallout radionuclides ²¹⁰Pb and ¹³⁷Cs. The anthropogenic radionuclide, ¹³⁷Cs, originating from atmospheric nuclear weapons testing can provide an important “first appearance” horizon of known age (1954-1955), providing much-needed validation for the sometimes uncertain interpretations associated with ²¹⁰Pb geochronology. However, while ¹³⁷Cs usually provides a strong signal in sediment in the northern hemisphere, total fallout of ¹³⁷Cs in the southern hemisphere was only 25% that of the north and the low activities of ¹³⁷Cs seen in Australian and New Zealand sediments can make its horizon of first appearance somewhat arguable. Low ¹³⁷Cs fallout also limited the size of the 1963-1964 fallout peak, a peak that is usually seen in northern hemisphere sediment profiles but is often difficult to discern south of the equator.This paper shows examples of the use of nuclear weapons fallout Pu as a chronomarker in sediment cores from Australia (3 sites) and New Zealand (1 site). The Pu profiles of five cores are examined and compared with the corresponding ¹³⁷Cs profiles and ²¹⁰Pb geochronologies. We find that Pu has significant advantages over ¹³⁷Cs, including greater measurement sensitivity using alpha spectrometry and mass spectrometric techniques compared to ¹³⁷Cs measurements by gamma spectrometry. Moreover, Pu provides additional chronomarkers associated with changes in the Pu isotopic composition of fallout during the 1950s and 1960s. In particular, the ²³⁸Pu/^239+240Pu activity ratio shows distinct shifts in the early 1950s and the mid to late 1960s, providing important known-age horizons in southern hemisphere sediments. For estuarine and near-shore sediments Pu sometimes has another significant advantage over ¹³⁷Cs due to its enrichment in bottom sediment relative to ¹³⁷Cs resulting from the more efficient scavenging of dissolved Pu in seawater by sediment particles.     

The distribution of Cs, K, Rb and Cs in plants in a Sphagnum-dominated peatland in eastern central Sweden

We record the distribution of ¹³⁷Cs, K, Rb and Cs within individual Sphagnum plants (down to 20 cm depth) as well as ¹³⁷Cs in vascular plants growing on a peatland in eastern central Sweden. In Calluna vulgaris¹³⁷Cs was mainly located within the green parts, whereas Andromeda polifolia, Eriophorum vaginatum and Vaccinium oxycoccos showed higher ¹³⁷Cs activity in roots. Carex rostrata and Menyanthes trifoliata showed variable distribution of ¹³⁷Cs within the plants. The patterns of ¹³⁷Cs activity concentration distribution as well as K, Rb and Cs concentrations within individual Sphagnum plants were rather similar and were usually highest in the capitula and/or in the subapical segments and lowest in the lower dead segments, which suggests continuous relocation of those elements to the actively growing apical part. The ¹³⁷Cs and K showed relatively weak correlations, especially in capitula and living green segments (0-10 cm) of the plant (r = 0.50). The strongest correlations were revealed between ¹³⁷Cs and Rb (r = 0.89), and between ¹³⁷Cs and stable Cs (r = 0.84). This suggests similarities between ¹³⁷Cs and Rb in uptake and relocation within the Sphagnum, but that ¹³⁷Cs differs from K.     

Cs,Co and K uptake by lettuce plants in two distributions of soil contamination

¹³⁷Cs and ⁶⁰Co, two of the radionuclides more representative of discharges from nuclear facilities, are of interest for radiological protections because of their great mobility in biosphere and affinity with biological systems. The aim of the present work is the investigation of the possible influence of the vertical distribution of ¹³⁷Cs and ⁶⁰Co in soil upon their uptake by lettuce as function of plant's growth. An experiment ad hoc has been carried out in field conditions. The results show that (i) the transfer of ¹³⁷Cs and ⁶⁰Co from soil to lettuce is independent by their distribution in soil, (ii) the soil–plant transfer factors of ¹³⁷Cs and ⁶⁰Co show a similar trend vs. growth stage, (iii) the ⁴⁰K transfer factor trend is different from those of anthropogenic radionuclides, and (iv) ¹³⁷Cs and ⁶⁰Co specific activities are about 1 Bq/kg, in the mature vegetable with soil activity from 9 to 21 kBq/m².     

Level and origin of 129I and 137Cs in lichen samples (Cladonia alpestris) in central Sweden

Lichen is a symbiosis between algae and fungi. They have for decades been used as bioindicators for atmospheric deposition of heavy metals, organic compounds and radioactive elements. Especially the species Cladonia alpestris and Cladonia rangiferina are important for the food chain lichen-reindeer-man.The concentration of ¹²⁹I was determined in lichen samples (Cladonia alpestris) contaminated by fallout from atmospheric nuclear tests explosions and the Chernobyl accident. The samples were collected at Lake Rogen District (62.3°N, 12.4°E) in central Sweden in the periods 1961-1975 and 1987-1998, and analysed with accelerator mass spectrometry (AMS) at CNA (Seville) to study its distribution in different layers. Data on the ¹³⁷Cs activity measured previously were also included in this study. The ¹²⁹I concentration ranged from (0.95 ± 0.13) × 10⁸ at g⁻¹ in 1961 in the uppermost layer to (14.2 ± 0.5) × 10⁸ at g⁻¹ in 1987 in deepest layer. The ¹²⁹I/¹³⁷Cs atom ratio ranged between 0.12 and 0.27 for lichen samples collected in the period 1961-1975, indicating weapons tests fallout. For lichen samples collected between 1987 and 1998 the behaviour of ¹³⁷Cs concentrations reflected Chernobyl fallout. The concentrations of the two radionuclides followed each other quite well in the profile, reflecting the same origin for both.From the point of view of the spatial distribution in the lichen, it appears that ¹²⁹I was predominantly accumulated in the lowest layer, the opposite to ¹³⁷Cs for which the highest amounts were detected systematically in the topmost layer of lichen. This vertical distribution is important for radioecology because lichen is the initial link in the food chain lichen-reindeer-man, and reindeer only graze the upper parts of lichen carpets.     

Evidence of the radioactive fallout in the center of Asia (Russia) following the Fukushima Nuclear Accident

It was recently reported that radioactive fallout due to the Fukushima Nuclear Accident was detected in environmental samples collected in the USA and Greece, which are very far away from Japan. In April-May 2011, fallout radionuclides (¹³⁴Cs, ¹³⁷Cs, ¹³¹I) released in the Fukushima Nuclear Accident were detected in environmental samples at the city of Krasnoyarsk (Russia), situated in the center of Asia. Similar maximum levels of ¹³¹I and ¹³⁷Cs/¹³⁴Cs and ¹³¹I/¹³⁷Cs ratios in water samples collected in Russia and Greece suggest the high-velocity movement of the radioactive contamination from the Fukushima Nuclear Accident and the global effects of this accident, similar to those caused by the Chernobyl accident.     

Influence of fertilizing on the Cs soil–plant transfer in a spruce forest of Southern Germany

Fertilization with 2.5 t/ha limestone: (83% CaCO₃, 8% MgO, 6% K₂O, 3% P₂O₅) reduces the ¹³⁷Cs transfer from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by a factor of 2–5 during at least 11 years as measured by the aggregated transfer factor T_ag. In 1997 and 2006 these results were confirmed by additional measurements of the ¹³⁷Cs transfer factor TF, related to the root zone (O_h horizon), which were explained by the selective sorption of ¹³⁷Cs in the root zone by measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP > 179 meq/kg) and non-fertilized soils (RIP < 74 meq/kg).