[en] A review of the published literature describing ¹³⁷Cs transfer to fungi was carried out, summarising the collated data to determine factors controlling transfer and identify an appropriate modelling approach to predict future contamination. ¹³⁷Cs transfer ratios (TR) are derived for fungi species collected within Europe and the CIS. Considerable variability in TRs is demonstrated, with TRs varying between <0.001 and >10 m² kg^-1 across all species and over three orders of magnitude for individual species (e.g. Boletus badius). Generally, meta-information (such as habitat and soil attributes) is poorly reported in the literature so that classification of the TR is limited to the effect of nutritional type (P<0.025) in the order mycorrhizal>saprophytic∼parasitic. Analysis of the literature data set (a heterogeneous source) suggests that there is no statistical evidence to indicate a decrease in TRs for 10 years after the Chernobyl accident. Spatial analysis of a data set for Belgium indicates variability in ¹³⁷Cs transfer within a sampling location, such that fruitbodies collected over a scale of approximately 5 km would show activities as variable as those collected over a much larger scale (∼ or>50 km). Therefore, it is proposed that the collated data sets for individual species can be used to derive 'best estimates' for the parameters describing the distribution of TRs. These can then be used to estimate an 'effective' TR, which, when combined with local soil deposition level and frequency and effect of culinary practices, can give an estimate of the activity of fungi consumed by the general population

[en] Available data have been analysed to test the hypothesis that both ³H and ¹⁴C transfer in mammals can be accounted for by an understanding of metabolism. Data obtained from various ¹⁴C and ³H experiments with rats and sheep have been analysed to assess the multi-component retention function of various organs and identify any relationship between half-times and component contribution. Our hypothesis was that component half-times for ¹⁴C and ³H are similar after intakes of organic compounds. Similarities in the tritium and carbon dynamics between rat and sheep were observed supporting the hypothesis. For fast and slow components of muscle half-time allometric relationships have been derived. The results obtained could be used in the development of a human biokinetic model. (author)

[en] Current farming practice in upland areas of Cumbria, England, affected by Chernobyl fallout is to remove lambs to lowland pastures for fattening prior to slaughter. The radiocaesium (137Cs and 134Cs) burden of lambs is rapidly lost via excreta deposited on the pasture. This may increase the radiocaesium activities in vegetation of these pastures. Studies were performed to assess the radioecological consequences of this practice. Results obtained from experiments were used to calibrate a soil/vegetation model which was used to predict long-term radiocaesium behavior

[en] The energy dependence of the neutron response of a liquid-NE213-scintillator cell was measured. (HSI)

[en] Preliminary predictions of the ¹³⁷Cs contamination of upland lambs in west Cumbria resulting from the Windscale and Chernobyl accident are presented. The predictions are made using the RUINS model and are tentative, particularly for the Windscale accident given the paucity of data available with which the model can be tested. In west Cumbria in the first year after each accident the Windscale fire is concluded to have resulted in higher ¹³⁷Cs activity concentrations of upland sheep for human consumption than the Chernobyl accident. This was principally due to the timing of the accidents, but could have been exacerbated significantly by differences in farming practice. However, deposition from the Chernobyl accident was more widespread therefore affecting a greater number of sheep. (author)

[en] In-air and in-phantom neutron spectra have been measured between 10 and 60 MeV for two field sizes on the Clatterbridge cyclotron by unfolding the response of a specially built NE213 scintillator. The in-phantom measurements show distinct spectral hardening with depth, which is reflected in changes in the spectrum-averaged mean neutron energy. These findings are confirmed using Monte Carlo calculations. (author)

[en] The protection of biota from ionising radiations needs reliable predictions of radionuclide dynamics in wild animals. Data specific for many wild animals radionuclide combinations is lacking and a number of approaches including allometry have been proposed to address this. However, for ¹⁴C and tritium, which are integral components of animals tissues and their diets, a different approach is needed in the absence of experimental data. Here we propose a metabolically based model which can be parameterized predominantly on the basis of published metabolic data. We begin with a metabolic definition of the ¹⁴C and OBT loss rate (assumed to be the same) from the whole body and also specific organs, using available information on field metabolic rate and body composition. The mammalian body is conceptually partitioned into compartments (body water, viscera, adipose, muscle, blood and remainder) and a simple model defined using net maintenance and growth needs of mammals. Intake and excretion, and transfer to body water are modelled using basic metabolic knowledge and published relationships. The model is tested with data from studies using rats and sheep. It provides a reliable prediction for whole body and muscle activity concentrations without the requirement for any calibration specific to ³H and ¹⁴C. Predictions from the model for representative wild mammals (as selected to be reference organisms within international programmes) are presented. Potential developments of a metabolic model for birds and the application of our work to human food chain modelling are also discussed. (author)

[en] A sward will often have significant amounts of soil adhered to the vegetation surfaces which will be ingested by grazing animals. If the soil is contaminated by radioactive fallout then it can serve as a dietary source of radionuclides, in addition to any root uptake by the plants. This study is an attempt to quantitatively assess the importance of soil adhesion as a source of radiocaesium to sheep using the RUINS model which simulates radiocaesium transfer in grazing systems. The method of simulating the contamination of vegetation surfaces used by the RUINS model is described, and the importance of the availability of radiocaesium associated with adhered soil relative to plant incorporated radiocaesium discussed. Two sets of simulations are presented : one in which the soil is treated as a medium providing a uniform availability of radiocaesium, and the second in which account is taken of the partitioning of radiocaesium in the soil between 'fixed' and 'labile' phases. (author)

[en] The uptake into vegetation of radiocaesium originating from the Chernobyl accident and from previous sources was compared at two upland sites in west Cumbria during November/December 1989. Both sites were in an area where restrictions are in place on the movement and slaughter of sheep due to high radiocaesium activities, and were known to have received comparatively high levels of deposition from both the 1957 Windscale accident and weapons fallout. The proportion of Chernobyl derived radiocaesium in the total radiocaesium inventory at each site was estimated using a ¹³⁴Cs:¹³⁷Cs ratio of 0.53 in Chernobyl fallout. Aged radiocaesium, mostly present for over 20 years, accounted for 59 ± 2.3 and 44 ± 2.8% (mean ± SE) of the ¹³⁷Cs deposit at the two sites. Initially, after the Chernobyl accident, the transfer of the recently deposited radiocaesium was reported to be greater than that of aged deposits. However, four years after the accident, the extent of transfer of Chernobyl radiocaesium from the top 4 cm of soil to vegetation is now similar to that of the aged radiocaesium. The similarity in behaviour of Chernobyl derived and aged radiocaesium suggests that future reductions in radiocaesium levels in vegetation, and therefore in sheep, will be slow. (author)

[en] A mechanistic model was developed to simulate the transport of radio-Cs in soils and its subsequent uptake by vegetation. The soil parameters in the model have been 'calibrated' by a process of parameter estimation by fitting model results to experimental data on the radio-Cs distribution in the soil profile. The experiment was used was not originally designed for this purpose and the data was non-ideal. Nevertheless it proved a useful initial test of the model. The experiment carried out at ITE Merlewood was intended to study the recycling of radio-Cs deposited by contaminated sheep faeces. Separate experiments were conducted to measure the rate at which radio-Cs is removed from faeces and it was therefore possible to determine source terms for the model. The cumulative rate of uptake by the vegetation was measured and at the end of the experiment the distribution of radio-Cs within the soil profile determined. (author)