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

Interception and retention of wet-deposited radiocaesium and radiostrontium on a ley mixture of grass and clover

The aims of this study were to assess the potential radioactive contamination of fodder in the case of accidental radionuclide fallout, and to analyse the relationship between interception and retention of radionuclides as a function of biomass and Leaf Area Index (LAI). The interception and the retention of wet deposited 134Cs and 85Sr in ley (a mixture of grass and clover) were measured after artificial wet deposition in a field train in Uppsala (eastern central Sweden). The field trial had a randomised block design with three replicates. 134Cs and 85Sr were deposited at six different growth stages during two growing seasons (20101 and 2011) using a rainfall simulator. The biomass was sampled in the centre of each parcel 2 to 3 h after deposition and at later growth stages (1 to 5) during the growing season. The above ground biomass and LAI were measured as well. The interception of radionuclides by the ley was largest at the late growth stages; the spike and tassel/flowering (code 5:6) in the 1st year, and at flowering/initial flowering (code 6:5) in the 2nd year. There was a correlation between radionuclide interception and above ground biomass, as well with LAI, for both radionuclides in both years. The highest activity concentrations of both radionuclides were measured after deposition at the late growth stages and were found to be higher in the 2nd year. There weathering half-lives were shorter at the earlier growth stages than at the later growth stages for both radionuclides. For the magnitude of deposition chosen in our experiment, it can be concluded that the above ground biomass is a good predictor and the LAI a more uncertain predictor of the interception of radiocaesium and radiostrontium by ley grass and clover

The distribution of Cs-137, 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 vulgaris 137Cs 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 ¼ 0.50). The strongest correlations were revealed between 137Cs and Rb (r¼ 0.89), and between 137Cs and stable Cs (r ¼ 0.84). This suggests similarities between 137Cs and Rb in uptake and relocation within the Sphagnum, but that 137Cs differs from K

Erfarenheter och motåtgärder inom jordbruket i Jämtlands län efter Tjernobylnedfallet

This report deals with various aspects, on countermeasures taken to diminish the impact of the Chernobyl accident, in critical fallout areas of Jämtland county, in order to reduce the contamination of the farmers produce and food stuff items with Cs-137 in the years 1986 – 1992. At the time of the Chernobyl radioactive fallout in Sweden the growing season had not yet started in Jämtland county (middle east Sweden), where two moun-tainous agriculture areas were critically contaminated with Cs-137. There was thus time for consideration if these areas, sensible for transfer of Cs-137 to crops, could be used for further agricultural produce, or had to be excluded. According-ly, the Swedish government delegated to Swedish radiation safety authority (SSI) to set up acceptable limits for contents Cs-137 in food stuff items, and to inform regional authorities (Agricultural boards) to facilitate the accomplishment of investigations and field research, which effectively could decrease the transfer of Cs-137 to agricultural crop and animal products. In Jämtland county, agriculture animal and soil advisers were to take part in the direct information of the farmers. Agr Dr I. Bjäresten, animal adviser, is initiator and head author of the report. She was much engaged on all levels of developing and testing the countermeasures to be employed by the farmers, and especially so in the years 1986 and 1987. Agr B. Jönsson, soil adviser is author of the supple-ment, where he re-ports about soil conditions and experiences from the field con-tamination areas investigated in years 1986-1990. Docent K. Rosén, research scientist in radioecology and soil sciences, SLU, is a staff member of research teams on the Jämtland county. He was engaged to get the report published. The report comprises a description of steps taken between the national authori-ties and the Jämtland county administration board in the unexpected situation after the Chernobyl serious fallout. The administration board made many delega-tions to the regional farming advisers, of which the latter in turn cooperated with the farmers concerned, of the “mysterious” radioactive fallout on their fields, and with university departments working with radioecology in Sweden. Their task was to estimate effective decrease of the different countermeasures recommend-ed and to a great extent implemented by the farmers on field and animal levels. The report can be considered as a narrative or account of experiences obtained by Bjäresten during her work with suitable countermeasures to decrease conta-mination of plant and animal products from the contaminated area considered

Accumulation of wet-deposited radiocaesium and radiostrontium by spring oilseed rape (Brássica napus L.) and spring wheat (Tríticum aestívum L.)

The accumulation of 134Cs and 85Sr within different parts of spring oilseed rape and spring wheat plants was investigated, with a particular focus on transfer to seeds after artificial wet deposition at different growth stages during a two-year field trial. In general, the accumulation of radionuclides in plant parts increased when deposition was closer to harvest. The seed of spring oilseed rape had lower concentrations of 85Sr than spring wheat grain. The plants accumulated more 134Cs than 85Sr. We conclude that radionuclides can be transferred into human food chain at all growing stages, especially at the later stages. The variation in transfer factors during the investigation, and in comparison to previous results, implies the estimation of the risks for possible transfer of radionuclides to seeds in the events of future fallout during a growing season is still subjected to considerable uncertainty

The effect of immersive virtual reality on proximal and conditioned threat

Virtual reality lets the user be immersed in a 3-dimensional environment, which can enhance certain emotional responses to stimuli relative to experiencing them on a flat computer screen. We here tested whether displaying two different types of threats in immersive virtual reality enhanced threat related autonomic responses measured by skin conductance responses (SCRs). We studied innate and learned threat responses because these types of threats have been shown to depend on different neural circuits in animals. Therefore, it is possible that immersive virtual reality may modulate one of these threats but not the other. Innate threat responses were provoked by the sudden appearance of characters at proximal egocentric distance, which were compared to the sudden appearance of distant characters (proximal threat). Learned threat responses were studied by conditioning two of the characters to an electric shock (conditioned threat) and contrasting SCRs to these characters with SCRs to two other characters that were never paired with shock. We found that displaying stimuli in immersive virtual reality enhanced proximal threat responses but not conditioned threat responses. Findings show that immersive virtual reality can enhance an innate type of threat responses without affecting a learned threat response, suggesting that separate neural pathways serve these threat responses. This article is licensed under a Creative Commons Attribution 4.0 International License, http://creativecommons.org/licenses/by/4.0/.</p