Biomedical subjects

T Sauras

Publications and source records attributed to T Sauras.

3 recordsLinked to original sources

PubMed2001

Interception, retention and translocation under greenhouse conditions of radiocaesium and radiostrontium from a simulated accidental source.

The behaviour of radioactive aerosols released from a severely damaged nuclear reactor and deposited on cereals was simulated under controlled conditions. 137Cs- and 90Sr-labelled aerosols were generated by volatilisation at high temperature of an artificially spiked pellet of depleted UO2. After cooling and maturation the aerosols were allowed to deposit on spring wheat (Triticum aestivum L. var. Arbon) cultures grown on lysimeters under greenhouse conditions. At the time of contamination the wheat plants were at different stages of development, from early vegetative growth (two leaves) until nearly mature (end of flowering). The estimated interception coefficient (micro) amounted to 13.1 m2 kg(-1); such a high value may be explained by the experimental conditions that created an over-saturated atmosphere during the contamination process and wet leaf surfaces. The first simulated rain, applied 6 days after the contamination, removed four times more 137Cs (54%+/-12 of the intercepted radionuclides) than 90Sr (15%+/-20) from the aerial parts. At harvest approximately 2% of the Sr and less than 1% of the Cs initially intercepted by the aerial parts is recovered for plants contaminated during the early development stages. A significantly higher proportion of the intercepted activity is still present for plants contaminated in the late development stages. The translocation to grains (TLF) increases when deposit occurs closer to the mature stage of the plant. The initial decrease of TLF values that we observed for strontium contamination in the earliest development stages is most probably due to the contribution of root uptake. Ploughing and re-sowing after the first rain, applied as a countermeasure reduced the 137Cs content in leaves and stems at harvest approximately 3 times but had no effect on the 90Sr content in vegetative organs. It reduced the 137Cs-contamination level in edible parts (grain) by a factor of 2 compared to the unploughed control, but doubled the 90Sr content.

Aerosols↗

PubMed2001

A soil sampling strategy for mapping trace element concentrations in a test area.

A sampling strategy, based on previous knowledge of a test area, was compared with a Reference Sampling in the frame of the EU-funded CEEM project. The aim was a comparison of sampling strategies for the drafting of concentration maps for a set of trace elements (Cd, Pb, Cu and Zn), with three-dimension information that can be used for risk assessment. The main constraint was that only 15 soil samples were to be analysed. The test area (in Dornach, Switzerland) included different soil types and land uses (forest, arable land and permanent grasslands). The sampling strategy proposed defined strata on the basis of land use, then applying a systematic regular sampling within each stratum. A composite sample was formed from each individual sample. In forests, H and Ah horizons were taken separately. In arable lands, a depth within the ploughed layer (0-15 cm) was analysed. In grasslands, samples were taken at two depths (0-10 and 10-20 cm) to provide information on the vertical variability. The comparison of the results obtained with those derived from the Reference Sampling allowed us to estimate if the information obtained from the proposed sampling strategy was sufficiently representative for an assessment of the level of elements considered. It was concluded that recommendations on sampling strategy depend on the interaction pattern of the element. In this case, for mobile trace elements, such as Cd, the information derived from sampling of two soil layers was not as important as that for the rest of metals studied that accumulated in the upper layer. If the H horizons in forests was not considered this led to unreliable predictions of the concentration levels, since the concentrations in H and Ah horizons differed irrespective of whether they were expressed in mg kg(-1) (the H horizon was enriched in those trace elements, except for Cd) and in mg m(-2) (the low bulk density of the H horizon led to a lower trace element level than in Ah horizon). Finally, in undisturbed systems such as grasslands, sampling 0-10 cm instead of 0-20 cm is recommended to prevent dilution of the concentration of trace elements.

Agriculture↗

PubMed2001

Soil- and plant-based countermeasures to reduce 137Cs and 90Sr uptake by grasses in natural meadows: the REDUP project.

The effectiveness of a set of soil- and plant-based countermeasures to reduce 137Cs and 90Sr transfer to plants was tested in natural meadows in the area affected by Chernobyl fallout. Countermeasures comprised the use of agricultural practices (disking + ploughing, liming and NPK fertilisation), addition of soil amendments and reseeding with a selection of grass species. Disking + ploughing was the most effective treatment, whereas the K fertiliser doses applied were insufficient to produce a significant increase in K concentration in soil solution. The application of some agricultural practices was economically justifiable for scenarios with a high initial transfer, such as 137Cs-contaminated organic soils. The use of soil amendments did not lead to a further decrease in transfer. Laboratory experiments demonstrated that this was because of their low radionuclide sorption properties. Finally, experiments examining the effect of plant species on radionuclide transfer showed that both transfer and biomass can depend on the plant species, indicating that those with high radionuclide root uptake should be avoided when reseeding after ploughing.

Agriculture↗