Abstract
In a greenhouse experiment, some features of Tritium migration from an aqueous feeding solution to white willow (Salix alba L.) habitat components and isotopic effects of hydrogen during the willow growth have been studied. A number of rate constants for tritiated water diffusion through pores, cell membranes and uptake through the root system (k = (8.44±0.03)•10-7 s-1); 3H/1H isotopic exchange in OH- groups of organic substances (k = 5.07•10-7); ,isotopic lightening, during photosynthesis (k = 5.00•10-8) were calculated from the experimental data. The rate constant of tritium transfer through the root system to intercellular sap of plants is 2.17±1.45•10-6 s-1. The tritium distribution between the feeding solution and the intercellular sap has come to equilibrium within 1-2 weeks. The fractionation factor (α) is 0.88-0.94 and does not depend on the concentration of 3H in the feeding solution. The rate constant of transformation of tritium into organically bound species is 8.6±3.0•10-7 s-1. The equilibrium has set from 4 to 11 weeks, α = 0.17-0.19 and does not depend on 3H concentration in the feeding solution. At the same time, strong isotopic effect of ,lightening, of the feeding solution, probably owing to transpiration, has been observed. The rate constant value of Tritium transpiration calculated from the experimental data is 2.67±0.27•10-8 s-1. The rate of tritium removal due to transpiration is proportional to its concentration in the feeding solution. The factor of tritium fractionation during transpiration is 1.35±0.08.
Highlights
Numerous studies conducted in the affected area of radioactive waste storage facilities showed that Tritium accumulates in various tree tissues in significant quantities [1,2,3,4,5,6].In living wood, tritium is concentrated in free water which is a part of plant intercellular sap, and in organic matter of plants by replacement of protons of ≡СН and ≡СОН groups for tritium
Tritium is concentrated in free water which is a part of plant intercellular sap, and in organic matter of plants by replacement of protons of ≡СН and ≡СОН groups for tritium
All water samples including the feeding solution from both containers were rectified with the addition of the oxidizer
Summary
Numerous studies conducted in the affected area of radioactive waste storage facilities showed that Tritium accumulates in various tree tissues in significant quantities [1,2,3,4,5,6].In living wood, tritium is concentrated in free water which is a part of plant intercellular sap (in the form of tritiated water H–O–T), and in organic matter of plants (cellulose, lignin etc.) by replacement of protons of ≡СН and ≡СОН groups for tritium. Numerous studies conducted in the affected area of radioactive waste storage facilities showed that Tritium accumulates in various tree tissues in significant quantities [1,2,3,4,5,6]. The rate and features of Tritium accumulation in natural plants within the area adjacent to radioactive waste storage facilities and nuclear power plants were not evaluated clearly because of the multifactor powerful and uncontrolled influence of the atmospheric precipitates, groundwater, solar radiation and winds. The difference between Tritium and Protium masses caused fractionation in chemical and physical processes. This leads to enrichment with a heavy isotope of one fraction in contrast to another fraction.
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