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Doctorat
Afrique du Sud
2021
Evaluation of primordial radionuclides and health impacts in soil, groundwater and food crops from the lower Swakop river, Namibia
Titre : Evaluation of primordial radionuclides and health impacts in soil, groundwater and food crops from the lower Swakop river, Namibia
Auteur : Amakali, Gideon
Université de soutenance : North-West University
Grade : Doctor of Philosophy in Science with Radiation Science 2021
Résumé partiel
Primordial radionuclides ; 238U, 232Th and 40K are found ubiquitously in varying
concentrations in environmental media. The exploration and mining related activities
have the potential to redistribute and concentrate primordial radionuclides to locations
accessible to members of the public. These radionuclides are the significant contributor
to the radiation doses received by humankind through various exposure pathways. The
Swakop river community and environmental activists expressed concern over possible
contamination of alluvial sand used in the construction industry and agricultural croplands
in the lower Swakop river due to uranium mining related activities in the surrounding
areas. This has motivated for the study to evaluate the primordial radionuclides in
groundwater, soil and food crops in the lower Swakop river and possible associated
health impacts. The study has also considered the portion of the Khan river that traversing
between the uranium mining activities before confluent with the Swakop river. A total of
63 soil samples were subjected to high purity germanium (HPGe) detector gamma
spectroscopic technique for the identification and quantification of primordial
radionuclides present. Inductive Coupled Plasma Mass Spectrometry (ICP-MS)
technique was used for the identification and quantification of total elements of U, Th and
K in water and food crops samples. The average activity concentrations of 238U in soil
samples across the study area were found to vary from 69.19±4.48 to 532.09±11.90
Bq.kg-1
. The average activity concentrations of 232Th in soil samples varied from
59.07±1.11 to 211.56±1.85 Bq.kg-1
, while for 40K were from 568.73±12.66 to
982.74±24.56 420 Bq.kg-1
. The activity concentrations of 40K and 238U in groundwater
along the Swakop river were varied from 737.66 to 2475.98 mBq.l-1 and 0.161 to 1116.47
mBq.l-1 with average values of 1449.22±181.85 and 313.43±127.62 mBq.l-1
, respectively,
while 232Th was below the detection limit of the technique used. The average activity
concentrations for 238U, 232Th and 40K in the groundwater samples collected from the
Khan river were 1282.55±230.04 mBq.l-1
, 0.167±0.09 mBq.l-1 and 1505.02±153.16 mBq.l1
, respectively
Page publiée le 15 avril 2022