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  • Author or Editor: B. Lukšienė x
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Abstract  

A scheme of fractionation of210Pb,210Bi,210Po forms present in air aerosols based on the combination of methods of radiochemical analysis and radiometric deteemination with leaching by different agents has been developed. The ratio between the210Pb,210Bi,210Po present in the aerosol samples was determined experimentally. Carbonate of210Pb, and210Po and210Bi forms connected with oxides prevai in the aerosol component of atmospheric air.

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Abstract  

A field experiment study was performed at the rural site of South-East Lithuania. The main tasks of the study included an evaluation of the peculiarities of partition of239Pu in soluble (239Pu(NO3)4,239PuCl3) and insoluble (239PuO2) forms in soddy and forest soil horizons. The results of durable experiments (418 and 326 days) have shown that from 44.1% to 92.2% of239Pu of investigated chemical forms were accumulated in the top (0–5 cm) soil layer. Some share (5.7–39.2%) of plutonium from studied chemical forms was found in the 5–20 cm layers of studied soil samples (columns). Obtained distribution of plutonium in soil layers may be attributed to the consideration that the migration rate to the soil depth for plutonium is 0.1–1.0 cm·y−1 but for some part of plutonium 10 times higher migration rate is characteristic as well. Plutonium transfer factor (TF) to the grassland plants was calculated, the values ranged from 10−2 to 10−1.

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Abstract  

Soil and meadow grass were sampled in the whole territory of Lithuania in 1992–2000. For the laboratory experiment, spring wheat Triticum aestivum L. “Nandu” was used because its root system type is similar to that of perennial meadow grass. The 137Cs soil-to-plant transfer factor of spring wheat was determined and the results were compared with the predicted values using a compartment model of soil-to-plant transfer and with the results of the field experiment. The results of comparing the measured and calculated transfer factor using the model show rather good coincidence, however, the calculated values were overestimated. The reason for overestimation can be that the uptake rate is not influenced only by the soil-to-plant transfer. The results of the model experiment (from 0.005 m2·kg−1 to 0.053 m2·kg−1) are close to those of the field measurements for grass (from 0.013 m2·kg−1 in 1992–1995 to 0.10 m2·kg−1 in 1999–2000).

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Abstract  

The aim of this study was to investigate the change of Pu oxidation states due to interaction with aerobic bacteria and fungi at low pH under laboratory conditions. Microorganisms were isolated from samples collected from the low-level radioactive waste repository within the confines of Ignalina NPP. Abilities of the fungi (Absidia spinosa var spinosa Lendn. and Paecilomyces lilacinus Thom Samson) as well as Gram-positive bacteria (Bacillus mycoides and Micrococcus luteus) and Gram-negative bacterium I-m1 to transform the oxidation states of Pu under aerobic conditions were investigated. Oxidized and reduced Pu was tested using two radiochemical procedures. The amount of reduced and oxidized Pu was determined by measuring alpha activity after radiochemical separation. The results have shown that all bacteria and fungi can very slightly alter oxidation states of Pu due to their microbial activity. All the microorganisms tested demonstrate quite a fast process of Pu biosorption under the experimental conditions.

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