Soil fertilisation with Cs-137-contaminated and uncontaminated wood ash as a countermeasure to reduce Cs-137 uptake by forest plants

The purpose of present study was to find out whether wood ash with a high pH value and neutralizing capacity reduces Cs-137 uptake by forest plants many years after the radionuclide fallout. The effects of one-time point fertilisation with Cs-137-contaminated and uncontaminated wood ash alone or in combination with KCl on Cs-137 transfer from soil to young leaves and green shoots of various dwarf shrubs and tree species were examined in a long-term fertilisation experiment (2012-2021) conducted in Bazar mixed forest, around 70 km from Chernobyl nuclear power plant. The results indicated minor effects of soil fertilisation, although there were differences between Cs-137 uptake by species and years. Soil amendment with Cs-137-contaminated wood ash generally did not affect Cs-137 uptake by young shoots and leaves of plants over the growing season in the first year and only slightly decreased Tag for Cs-137 in the following years. The effect of a single application of Cs-137-uncontaminated wood ash on reducing Cs-137 uptake by plants was generally negligible. Application of Cs-137-contaminated wood ash in combination with KCl reduced plant Cs-137 uptake by about 45%, however, such reduction was only significant in some years for bilberry berries, young leaves and green shoots of lingonberry and alder buckthorn. Thus application of wood ash to Cs-137-contaminated forest soil many years after radionuclide fallout generally does not reduce Cs-137 uptake by forest vegetation in a mixed forest ecosystem and this countermeasure should be applied with caution

Long-term field and laboratory leaching tests of cemented radioactive wastes

Experiments with real and simulated radioactive cementitious wasteforms were set up to compare the leaching behaviour of cementitious wasteforms containing nuclear power plant operational waste in field and laboratory test conditions. Experiments revealed that the average annual Cs-137 leach rate in deionised water was about thirty-five times greater compared with the measured average value for the 1st year of the field test. Cumulative leached fraction of Cs-137 for 1st year (3.74%) was close to values reported in literature for similar laboratory experiments in deionised water, however more than two orders of magnitude higher than the 1st year leached fraction of Cs-137 in the repository test (0.01%). Therefore, to compare field and laboratory test results, a scaling factor is required in order to account for surface to volume factor difference, multiplied by a temperature factor and a leach rate decrease coefficient related to the ground water composition. (C) 2011 Elsevier B.V. All rights reserved

Factors influencing the accumulation of fallout cesium-137 in mule deer

May 1965.Includes bibliographical references (pages 131-142).Author's name on piece is Floyd Ward Whicker.Covers not scanned.Print version deaccessioned 2021.This investigation was concerned with factors influencing the accumulation of fallout cesium-137 in a wild population of mule deer, Odocoileus hemionus, in the Cache la Poudre drainage of north-central Colorado. Air, precipitation, soils, twelve deer forage species, and deer were sampled periodically from various elevations within the study area over a three year period. Experimental sampling designs were primarily factorial with sufficient replication to allow statistical treatment of data. Materials were assayed for Cs-137 using the technique of gamma-ray spectrometry. Air concentrations of Cs-137 were maximal in 1963. Concentrations were significantly higher during spring and early summer months of each year. Maximum deposition of Cs-137 by precipitation in 1964 occurred during April, May, and June. Measurable quantities of fallout were transported by dust, pollens, and other air-borne debris during dry, windy periods. The majority of Cs-137 in soils was located in the 0-1 inch layer. Soil radio activity generally increased with elevation and associated higher average precipitation rates. Maximum vegetational levels of Cs-137 were observed in 1963. Species collected during the summer and fall above 8,500 feet were generally higher in cesium than species collected during the winter and spring from lower elevations. Significant differences between species growing on the same plots were found. Significant differences in Cs-137 concentrations of given species between locations were also encountered. The location effect was attributed mostly to phenomena associated with elevation. Leaves were generally higher in Cs-137 than stems. Maximum levels of Cs-137 in deer were observed in 1963. Maximum levels within years occurred during the summer months in animals collected above 8,500 feet elevation. Regression analyses of muscle Cs-137 versus elevation indicated significant correlations. Evidence indicated a high degree of correlation between Cs-137 levels in vegetation and deer. It was concluded that the degree of foliage contamination and food habits were the most important factors contributing to Cs-137 burdens in deer. A Cs-137/K discrimination factor between the diet and muscle of 0.9 was estimated from the rumen samples. Neither sex nor age produced statistically significant variations in muscles Cs-137. Inhalation, the drinking of surface waters, and the ingestion of snow were minor sources of Cs-137 intake by deer in comparison to the ingestions of forage

Chernobyl still with us : (137)Caesium activity contents in seabed sediments from the Gulf of Bothnia, northern Baltic Sea

Anthropogenic radionuclides are among those human impacts, which can be seen widely in the marine and terrestrial ecosystems. Fallout from the 1986 Chernobyl nuclear power plant accident has rendered the Baltic Sea as the most polluted marine body in the world with respect to Cs-137. This research investigated sediment cores from 56 sites around the Gulf of Bothnia, Baltic Sea. Radioactivity from Cs-137 in sediments has generally declined due to natural/radioactive decay of Cs-137 over the last decades. However, Cs-137 contents in subsurface sediments remain at elevated levels compared to pre-Chernobyl levels. The highest Cs-137 activity contents in subsurface sediments (>4000 Bg kg(-1)) occur in coastal areas including estuaries. These areas often experience severe anthropogenic pressure. The southern Bothnian Sea, Kvarken archipelago, and southern Bothnian Bay all show elevated Cs-137 values in subsurface sediments. Sedimentary Cs-137 can also help constrain recent rates of sedimentation. Post-Chernobyl sedimentation rates in the Gulf of Bothnia varied from 0.1 to 4.8 cm/year with an average sedimentation rate of 0.54 cm/year.Peer reviewe

Study of Cs-137 Dispersion by the Fukushima Nuclear Power Plant Accident through Radioactivity Analysis of Mosses

The dispersion of Cs-137 by the Fukushima Daiichi Nuclear Power Plant accident (Fukushima accident)was studied through a radioactivity analysis of more than 120 samples of mosses. Moss is a plant that grows abundantly any area of Japan. It was reconfirmed that mosses have an extremely higher ability to retain Cs-137 than other plants. The reason is considered to be that the moss absorbs Cs-137 in rainwater directly into the body not through the rhizoids from the soil. The difference in Cs-137 retention between different types of mosses is small. It is also easy to estimate the fallout value as the Cs-137 deposition in a unit of Bq/m2 because the moss forms two-dimensional colony.Mosses around eastern Fukushima Prefecture were collected and their radioactivity was analyzed. It was revealed that the radioactivity analysis of mosses is useful for obtaining the map of Cs-137 deposition transported from the nuclear power plant. The Cs-137 deposition map supports the estimation that the plume from the Fukushima Nuclear Power Plant transported to the Koriyama City via the Kawauchi Village in the morning of March 15, 2011, and transported again to the Koriyama City via the Iitate Village and the Fukushima City in the afternoon

ANALYSIS OF CS-137 TO CS-134 ACTIVITY RATIO FOR FAILED FUEL EXPOSURE ESTIMATION

The Cs-134 to Cs-137 activity ratio of the Cs-134 and Cs-137 fission products released from failed fuel rods into primary coolant is very useful to identify the exposure along with the fuel batch of the failed fuel. The calculated and measured Cs-137 to Cs-134 radioactivity ratios of failed BWR and PWR fuels are compared and analyzed for better understanding of their relationship.  Moreover, the impacts of power uprate and fuel reload outage on calculated Cs-137 to Cs-134 activity ratios are studied and the physics behind the impacts are provided

Transfer of river-discharged Cs-137 in estuaries : a case study from Vefsna river and the Vefsnfjord in Nordland, Norway

Several decades after the Chernobyl accident, it is still detectable activities of Cs-137 in the environment. Norway was highly affected by radioactive fallout, where one of the locations that received the highest doses of Cs-137 was Nordland county. Recent studies have shown that the Vefsnfjord is amongst the fjords in Norway with highest activity of Cs-137. The Vefsna river feeds into the Vefsnfjord, creating an estuarine environment with a brackish surface layer, and an increasing salinity gradient outward the fjord. In this work, Cs-137 in the estuarine environment has been studied in water, sediments, and biota to identify changes in speciation, mobility, and bioavailability of Cs-137 outward the Vefsnfjord with increased salinity and distance to the river outlet. The activity concentration of Cs-137 in water decreased as the salinity increased, from 4.0 ± 0.6 Bq/m3 to 3.0 ± 0.2 Bq/m3. By performing in situ fractionation of water and measuring activity of Cs-137 using HPGe-detector, it was reviled that the dominating specie was LMM in both freshwater and seawater, with low activity concentration of colloids (<0.86 ± 0.14 Bq/m3) and particles (0.55 ± 0.087 Bq/m3) in freshwater. Cs-137 associated with river discharged colloids and particles was only identified in the lowest salinity in the estuary (5 PSU) and was lower than estimated by dilution. On the contrary, activity concentration of LMM species was slightly increased in low salinity seawater compared with the riverine water and, and higher than estimated by dilution, likely caused by remobilization from river transported colloids and particles. Grain size analysis of surface sediments showed that the riverine sediments mostly consisted of sand (>90%), while silt (45-86%) was the dominating size fraction in marine sediments. The content of clay was generally low (0.03-2%). The mineral structure was established by performing XRD analysis, where the silt samples consisted mostly of quartz and albite, while clay contained muscovite. The activity concentration of Cs-137 in sediments increased with increased distance outwards the fjord (from 35 ± 1.5 Bq/kg to 152 ± 6.0 Bq/kg), which can be explained by reduced content of sand, while the content of silt increased. Results show that the activity concentration of Cs-137 in sand was low (<66 ± 7.3 Bq/kg), while the activity concentration of Cs-137 in silt was higher, especially in the riverine sediments (529 ± 16 Bq/kg). However, the highest activity concentration of Cs-137 was found in riverine clay (3631 ± 28 Bq/kg). While it was no significant change activity concentration of Cs-137 in sand from marine sediments compared to riverine sediments, a significant reduction in activity concentration was observed for silt and clay. Sequential extraction of silt and clay from riverine- and marine sediments showed that Cs-137 was irreversibly bound to both silt and clay, as 42-58% of Cs-137 was extracted with 7 M nitric acid, while the remaining Cs-137 was left in the residue. Cs-137 bound to silt showed somewhat higher mobility than Cs-137 bound to clay, but it was no significant difference in mobility between riverine sediments and marine sediments. Apparent Kd values for Cs-137 showed an increasing trend for sediments (total) with increased distance out the fjord from (7.4± 0.99) ·103 L/kg to (2.6± 0.26) ·104 L/kg. The Kd was high for silt ((1.1 ± 0.15)·105 L/kg) and clay ((5.5 ± 0.74) ·105 L/kg) from riverine sediments, but a significant decrease in Kd was observed for silt and clay in brackish water. However, based on the results from sequential extraction, it is unlikely that remobilization of Cs-137 from silt and clay is the cause of decreased Kd in marine sediments. The biological uptake of Cs-137 was studied in seaweed (F.vesiculosus, L.digitata) and blue mussels (M.edulis) from various locations in the Vefsnfjord. However, the activity concentration in seaweed was low (0.65 ± 0.04 Bq/kg – 1.04 ±0.04 Bq/kg), and under the detection limit (<0.17 Bq) in blue mussels. The BCF in seaweed (171 ± 21 L/kg - 247 ± 25 L/kg) was higher than reported in IAEA handbooks. The highest activity concentration and BCF was obtained in a mixed sample containing seaweed from the inner parts of the fjord, suggesting that the uptake was higher in low salinity water. Based on the obtained results in this study, it can be established that the speciation of Cs-137 in freshwater from river Vefsna change upon mixing with seawater from the Vefsnfjord. LMM species is likely to have remobilized from suspended particles and colloids originating from the Vefsna river. Surface sediments, however, seems not to be a significant contributor to remobilisation of LMM species. Further, LMM Cs-137 was prone to biological uptake, such as seaweed. The results highlight the importance of obtaining knowledge about the processes affecting the speciation, mobility and biological uptake of radionuclides, in order to predict the transfer of radionuclides in estuaries and coastal areas.Flere tiår etter Tsjernobylulykken er det fortsatt målbare aktivitetsnivåer av Cs-137 in miljøet. Norge var sterkt påvirket av radioaktivt nedfall, og et av områdene som mottok de høyeste dosene var Nordland fylke. Nyere studier viser at Vefsnfjorden er en av fjordene i Norge med høyest aktivitet av Cs-137. Elven Vefsna munner ut i Vefsnfjorden og danner et estuar med et øvre brakkvannslag, og en økende saltgradient utover fjorden. I dette arbeidet har Cs-137 i vann, sedimenter og biota blitt undersøkt for å identifisere endringer i tilstandsformer, mobilitet og biotilgjengelighet med økt salinitet og avstand fra elvemunningen.M-K

Distribution of cesium-137 in reindeer

The influence of the Chernobyl accident in 1986 on the Finnish reindeer herding area was much smaller than the effects of the nuclear bomb tests in the 1960s. Only in one small area somewhat more Cs-137 was deposited than in the rest of the reindeer herding area. From that area 20 reindeer were chosen for investigation of the distribution of Cs-137. All tissues, organs, the skeleton, digestive tract, hide, head and hooves were sampled quantitatively. Three reindeer were pregnant and also the foetuses were studied. The Cs-137 amounts were determined by gammaspectrometric measurements. The results showed that the differences in the Cs-137 concentrations between muscle tissue from different parts of an individual reindeer were not more than 10 percent. Thus it is not essential from which part of the reindeer meat samples for surveillance purposes are taken. The concentration of Cs-137 in edible tissues other than muscle was lower except in the kidneys and scapula cartilage