Fractionation of 137Cs and Pu in natural peatland

• Published in: Journal of environmental radioactivity Vol. 134; pp. 14 - 20
• Main Authors: Mihalík, Ján, Bartusková, Miluše, Hölgye, Zoltán, Ježková, Tereza, Henych, Ondřej
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-08-2014; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Cesium; Ecotoxicology, biological effects of pollution; Fundamental and applied biological sciences. Psychology; Peat; Plutonium; Sequential extraction; Sphagnum; Terrestrial environment, soil, air; Vertical distribution; Cesium; Sequential extraction; Plutonium; Peat; Vertical distribution; Sphagnum; Radioactive pollution; Bryophyta; Concentration; Radioisotope; Soil pollution; Sphagnobrya; Soils; Vegetation
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2014.02.015

High Cs-137 concentrations in plants growing on peatland inspired us to investigate the quantity of its bioavailable fraction in natural peat. Our investigation aims to: a) estimate the quantity of bioavailable Cs-137 and Pu present in peat, b) verify the similarity of Cs-137 and K-40 behaviours, and c) perform a quantification of Cs-137 and Pu transfer from peat to plants. We analysed the vertical distribution of Cs-137 and Pu isotopes in the peat and their concentrations in plants growing on these places. Bioavailability of radionuclides was investigated by sequential extraction.
Sequential analyses revealed that it was the upper layer which contained the majority of Cs-137 in an available form while deeper layers retained Cs-137 in immobile fractions. We can conclude that 18% of all Cs-137 in the peat is still bioavailable. Despite of the low quantity of bioavailable fraction of Cs-137 its transfer factor reached extremely high values. In the case of Pu, 64% of its total amount was associated with fulvic/humic acids which resulted in the high transfer factor from peat to plants. 27 years after the Chernobyl nuclear accident, the significant part of radionuclides deposited in peatland is still bioavailable.
•Decrease of exchangeable 137Cs and its increase in residual fraction with depth.•High 137Cs transfer factor contrary to its low quantity in bioavailable fractions.•Fulvic/humic acids are a more effective carrier for Pu than for Cs.