Abstract
A thorough knowledge of the behavior of long-lived radionuclides in the biosphere is needed for the safety assessment of deep underground nuclear waste repositories. Soils support terrestrial food chains and are thus a key compartment in the determination of transfers of radionuclides to Man. Tyre prediction of soil-to-plant transfers is based on the characterization of the phyto-availability of radionuclides in soils by taking into account all the transfer processes inside the soil profile. The aim of this study was to predict phyto-availability of radionuclides in cultivated soils. The phyto-availability of two radionuclides varying in their mobility, {sup 63}Ni and {sup 99}Tc, was studied a the level of the sieved soil sample and of the cultivated soil profile. Three soils showing contrasted hydraulic and physico-chemical properties were sampled in order to isolate undisturbed soil cores (50 cm x 50 cm): a rendzina, a clayey colluvial soil and a sandy-loam acidic soil. The cores were placed in a greenhouse and equipped with porous cups and leachate collectors in order to sample soil solution and drainage water. The first year, maize (Zea mays L.) was grown and irrigated. Soils were contaminated once on the surface by irrigation at the beginning of the summer
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Citation Formats
Denys, S.
Prediction of the phyto-availability of two radionuclides ({sup 63}Ni and {sup 99}Tc) in soils; Prediction de la phytodisponibilite de deux radionucleides ({sup 63}Ni et {sup 99}Tc) dans les sols.
France: N. p.,
2001.
Web.
Denys, S.
Prediction of the phyto-availability of two radionuclides ({sup 63}Ni and {sup 99}Tc) in soils; Prediction de la phytodisponibilite de deux radionucleides ({sup 63}Ni et {sup 99}Tc) dans les sols.
France.
Denys, S.
2001.
"Prediction of the phyto-availability of two radionuclides ({sup 63}Ni and {sup 99}Tc) in soils; Prediction de la phytodisponibilite de deux radionucleides ({sup 63}Ni et {sup 99}Tc) dans les sols."
France.
@misc{etde_20485102,
title = {Prediction of the phyto-availability of two radionuclides ({sup 63}Ni and {sup 99}Tc) in soils; Prediction de la phytodisponibilite de deux radionucleides ({sup 63}Ni et {sup 99}Tc) dans les sols}
author = {Denys, S}
abstractNote = {A thorough knowledge of the behavior of long-lived radionuclides in the biosphere is needed for the safety assessment of deep underground nuclear waste repositories. Soils support terrestrial food chains and are thus a key compartment in the determination of transfers of radionuclides to Man. Tyre prediction of soil-to-plant transfers is based on the characterization of the phyto-availability of radionuclides in soils by taking into account all the transfer processes inside the soil profile. The aim of this study was to predict phyto-availability of radionuclides in cultivated soils. The phyto-availability of two radionuclides varying in their mobility, {sup 63}Ni and {sup 99}Tc, was studied a the level of the sieved soil sample and of the cultivated soil profile. Three soils showing contrasted hydraulic and physico-chemical properties were sampled in order to isolate undisturbed soil cores (50 cm x 50 cm): a rendzina, a clayey colluvial soil and a sandy-loam acidic soil. The cores were placed in a greenhouse and equipped with porous cups and leachate collectors in order to sample soil solution and drainage water. The first year, maize (Zea mays L.) was grown and irrigated. Soils were contaminated once on the surface by irrigation at the beginning of the summer season. After harvest, in early October, winter wheat (Triticum aestivum L.) was sawn. The cores were again contaminated in March: once in the case of {sup 63}Ni and three tinges for {sup 99}Tc. Transfers of radionuclides to water and aerial parts of crops were monitored throughout the two-year experiment. Results showed that the phyto-availability of radionuclides can be estimated from that of chemical or isotopic analogues ire the case of simple or multiple contamination. {sup 63}Ni is diluted in the pool of isotopically exchangeable Ni{sup 2+} ions in the soils. {sup 99}TcO{sub 4}- is diluted in the pool of available NO{sub 3}- ions. Radionuclides stayed in the upper layer of the soils until harvest due to the high evapotranspiration rate of maize. Transfer to crops was different among soils and reached 70% for {sup 99}Tc and 0.4% for {sup 63}Ni, thus confirming the values obtained in pot experiments. Hence, leaching of radionuclides in the profile had a negligible effect on the soil-to-plant transfer. During the second year, uptake of {sup 99}Tc and {sup 63}Ni from repeated contamination was similar to that from a single contamination. During culture, competition between TcO{sub 4}- and NO{sub 3}- ions for root absorption was verified at the soil core level. Measurement of the phyto-availability of radionuclides can be based on the use of classical methods applied to sieved soil samples. K{sub d}, and CR values for {sup 63}Ni and {sup 99}Tc obtained in such conditions could be used to map phyto-availability for specific sites. Such maps could be powerful tools for the selection of site-specific transfer parameters values of safety assessment models. (author)}
place = {France}
year = {2001}
month = {Oct}
}
title = {Prediction of the phyto-availability of two radionuclides ({sup 63}Ni and {sup 99}Tc) in soils; Prediction de la phytodisponibilite de deux radionucleides ({sup 63}Ni et {sup 99}Tc) dans les sols}
author = {Denys, S}
abstractNote = {A thorough knowledge of the behavior of long-lived radionuclides in the biosphere is needed for the safety assessment of deep underground nuclear waste repositories. Soils support terrestrial food chains and are thus a key compartment in the determination of transfers of radionuclides to Man. Tyre prediction of soil-to-plant transfers is based on the characterization of the phyto-availability of radionuclides in soils by taking into account all the transfer processes inside the soil profile. The aim of this study was to predict phyto-availability of radionuclides in cultivated soils. The phyto-availability of two radionuclides varying in their mobility, {sup 63}Ni and {sup 99}Tc, was studied a the level of the sieved soil sample and of the cultivated soil profile. Three soils showing contrasted hydraulic and physico-chemical properties were sampled in order to isolate undisturbed soil cores (50 cm x 50 cm): a rendzina, a clayey colluvial soil and a sandy-loam acidic soil. The cores were placed in a greenhouse and equipped with porous cups and leachate collectors in order to sample soil solution and drainage water. The first year, maize (Zea mays L.) was grown and irrigated. Soils were contaminated once on the surface by irrigation at the beginning of the summer season. After harvest, in early October, winter wheat (Triticum aestivum L.) was sawn. The cores were again contaminated in March: once in the case of {sup 63}Ni and three tinges for {sup 99}Tc. Transfers of radionuclides to water and aerial parts of crops were monitored throughout the two-year experiment. Results showed that the phyto-availability of radionuclides can be estimated from that of chemical or isotopic analogues ire the case of simple or multiple contamination. {sup 63}Ni is diluted in the pool of isotopically exchangeable Ni{sup 2+} ions in the soils. {sup 99}TcO{sub 4}- is diluted in the pool of available NO{sub 3}- ions. Radionuclides stayed in the upper layer of the soils until harvest due to the high evapotranspiration rate of maize. Transfer to crops was different among soils and reached 70% for {sup 99}Tc and 0.4% for {sup 63}Ni, thus confirming the values obtained in pot experiments. Hence, leaching of radionuclides in the profile had a negligible effect on the soil-to-plant transfer. During the second year, uptake of {sup 99}Tc and {sup 63}Ni from repeated contamination was similar to that from a single contamination. During culture, competition between TcO{sub 4}- and NO{sub 3}- ions for root absorption was verified at the soil core level. Measurement of the phyto-availability of radionuclides can be based on the use of classical methods applied to sieved soil samples. K{sub d}, and CR values for {sup 63}Ni and {sup 99}Tc obtained in such conditions could be used to map phyto-availability for specific sites. Such maps could be powerful tools for the selection of site-specific transfer parameters values of safety assessment models. (author)}
place = {France}
year = {2001}
month = {Oct}
}