Contribution to the study of depth profile of soil radioactivity as a function of land use
Description
The aim of this work is to study the depth profile of soil radioactivity. Results show that profiles of potassium-40, uranium-238 and thorium-232 vary according to the depth. For the rice field study site, minimum concentrations are respectively 89 ±10 Bq.Kg-1, 11±1 Bq.Kg-1 and 46 ±3 Bq. Kg-1 which are situated within the ploughing depth 0-30 cm. The maximum values are 220 ±8 Bq.Kg-1, 16 ±1 Bq.Kg-1 et 57 ±3 Bq.Kg-1 and located under the ploughing depth. The low activity within the ploughing depth can be explained by radionuclide transfer from soil to plants. Results from cultivated field and uncultivated field show that beryllium-7 profile decreases exponentially with depth. The maximum values are 51 ± 11 Bq.Kg-1 for cultivated site and 49 ±5 Bq.Kg-1 for uncultivated site, within 0-1 cm of soil subsurface. Relaxation depth are 2,56 Kg.m-2 for cultivated field and 2,85 Kg.m-2 for uncultivated field. Therefore, relaxation depth depends on soil use. The beryllium-7 inventories are 224 +-56 Bq.m-2 and 204+-40 Bq.m-2 respectively. Beryllium-7 variation is related to short term soil loss caused by rainfall events. Then, beryllium-7 allows studying short term erosion. But measurement accuracy needs to be improved.
Availability note (English)
Available at Madagascar INSTN, B.P. 4279 Antananarivo (Madagascar)Abstract (French)
Le but de ce travail est d'etudier le profil en profondeur de la radioactivite en fonction de l'utilisation des sols. Les resultats montrent que les profils du potassium-40, de l'uranium-238 et du thorium-232 varient avec la profondeur. Pour le site riziere, les teneurs minimales sont respectivement de 89 ±10 Bq.Kg-1, 11±1 Bq.Kg-1 et 46 ±3 Bq. Kg-1 et se trouvent au niveau de la couche labouree, de 0 a 30 cm. Les teneurs maximales sont de 220 ±8 Bq.Kg-1, 16 ±1 Bq.Kg-1 et 57 ±3 Bq.Kg-1 et se situent en dessous de la couche de labour. L'appauvrissement des teneurs de ces trois radionucleides dans la couche labouree s'explique par le phenomene du transfert de ces radionucleides du sol vers les plantes. Les resulats issus des deux autres sites, champ cultive et champ non cultive montrent que le profil du beryllium-7 decroit exponentiellement avec la profondeur. Les teneurs maximales sur ces deux sites sont respectivement de 51 ± 11 Bq.Kg-1 et 49 ±5 Bq.Kg-1, et situees entre 0 et 1 cm de la surface. Les profondeurs de relaxations sont de 2,56 Kg.m-2 pour le champ cultive et de 2,85 Kg.m-2 pour le champ non cultive. Ainsi, la profondeur de relaxation depend de l'utilisation des sols. Son inventaire est de 224 +-56 Bq.m-2 pour le champ cultive et de 204+-40 Bq.m-2 pour le champ non cultive. La variation de ce dernier etant fonction de la perte en terre liee a un evenement court, l'utilisation de beryllium-7 avec des donnees pluviometriques permettrait de faire l'etude de l'erosion des sols a court terme. Mais il faut ameliorer la precision des mesures.Additional details
Additional titles
- Original title (French)
- Contribution a l'etude du profil en profondeur de la radioactivite en fonction de l'utilisation des sols
Publishing Information
- Publisher
- Madagascar INSTN
- Imprint Place
- Antananarivo (Madagascar)
- Imprint Pagination
- [60 p.]
INIS
- Country of Publication
- Madagascar
- Country of Input or Organization
- Madagascar
- INIS RN
- 41112721
- Subject category
- S54: ENVIRONMENTAL SCIENCES;
- Resource subtype / Literary indicator
- Thesis, Non-conventional Literature
- Descriptors DEI
- BERYLLIUM 7; GAMMA SPECTROSCOPY; NATURAL RADIOACTIVITY; POTASSIUM 40; RADIATION MONITORING; RADIOACTIVITY; RADIONUCLIDE MIGRATION; SITE CHARACTERIZATION; SOILS; THORIUM 232; URANIUM 238
- Descriptors DEC
- ACTINIDE NUCLEI; ALKALINE EARTH ISOTOPES; ALPHA DECAY RADIOISOTOPES; BERYLLIUM ISOTOPES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; ENVIRONMENTAL TRANSPORT; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; HEAVY NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LIGHT NUCLEI; MASS TRANSFER; MONITORING; NANOSECONDS LIVING RADIOISOTOPES; NUCLEI; ODD-ODD NUCLEI; POTASSIUM ISOTOPES; RADIOACTIVITY; RADIOISOTOPES; SPECTROSCOPY; SPONTANEOUS FISSION RADIOISOTOPES; THORIUM ISOTOPES; URANIUM ISOTOPES; YEARS LIVING RADIOISOTOPES
Optional Information
- Notes
- 23 refs., 9 tabs., 12 figs.,
- Funding organization
- Madagascar INSTN, Antananarivo (Madagascar)