IMPACT OF RAPID WARMING ON THE TRANSFER OF 60Co, 137Cs AND 54Mn FROM SOIL TO GRASS AND WITHIN THE FOOD CHAIN
Miryana Varbeva, Petya Kovacheva
Received: 29 FEB 2016,
Received revised: 22 APR 2016,
Accepted: 30 APR 2016,
Published online: 26 DEC 2016
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Rapid changes of the environmental temperature can alter soil characteristics and influence the migration ability and bioavailability of the radionuclides. Elucidation of the effects of extreme weather conditions on the transfer factors of radionuclides in different soil types is especially important for adequate risk assessment after radioactive contamination. This paper presents the impact of a rapid increase of environmental temperature for a period of one month on the bioaccumulation of 60Co, 137Cs and 54Mn from three soil types to orchard grass. The experiment was performed by soil samples, taken from the surface soil layer 0-10 cm of Albic cambisol, Calcaric chernozem and Gleyic fluvisol soils (classified according to World Reference Base for Soil Resources/FAO) from Bulgaria. The samples were contaminated by a radioactive solution of 60Co, 137Cs and 54Mn, separated into two subsamples and stored during one month at two temperature regimes: 15 оС and 40 оС by using of a climate chamber. Afterwards, the soils were planted with orchard grass and stored at 15 oC during two weeks until growing and the transfer factors were determined. The results showed that rapid warming during one month after radioactive contamination caused a decrease of the transfer of 137Cs from all studied soils to orchard grass. The decrease of the transfer factors of 60Co and 54Mn from the soil with high cation-exchange capacity, higher quartz and muscovite content was determined, while the increase of the transfer factors of 60Co and 54Mn from the soil with very low cation-exchange capacity and lower content of quartz and micaceous minerals was registered. Prognostic maximum specific activities of the radionuclides in the investigated soils, at which milk and meat are harmless to be consumed, were calculated referring to the obtained data.
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