Activity concentration of natural radionuclides in sediments of Bree, Klein-Brak, Bakens, and uMngeni rivers and their associated radiation hazard indices

Abstract

A hyper-pure germanium (HPGe) detector was used to measure the activity concentrations in sediment samples of rivers in South Africa, and the associated radiological hazard indices were evaluated. The results of the study indicated that the mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the sediment samples from the oil-rich areas are 11.13, 7.57, 22.5 $Bq.k{g}^{-1}$; 5.51, 4.62, 125.02 $Bq.k{g}^{-1}$ and 7.60, 5.32, 24.12 $Bq.k{g}^{-1}$ for the Bree, Klein-Brak and Bakens Rivers, respectively. In contrast, the control site (UMngeni River) values were 4.13, 3.28, and 13.04 $Bq.k{g}^{-1}$ for ²²⁶Ra, ²³²Th, and ⁴⁰K. The average excess lifetime cancer risks are 0.394 × ${10}^{-3}$, 0.393 × ${10}^{-3}$, 0.277 × ${10}^{-3}$ and 0.163 × ${10}^{-3}$ for sediment samples at Bree, Klein-Brak, Bakens, and uMngeni rivers. All obtained values indicated a significant difference between the natural radionuclide concentrations in the samples from the rivers in oil-rich areas compared to those of the non-oil-rich area. The values reported for the activity concentrations and radiological hazard indices were below the average world values; hence, the risk of radiation health hazard was negligible in all study areas.

Keywords:

• concentrations
• hazard indices
• natural radionuclides
• radiation
• sediments

ACKNOWLEDGEMENTS

The authors are grateful to iThemba LABS, Capetown, South Africa, most notably Dr Peane Maleka and Mistura B. Ajani, for giving us access to their Environmental Research Laboratory (ERL) to measure the radioactivity levels in the samples. They were supportive during the analysis of the samples. Acknowledgements are also extended to the research farm's technical staff and the School of Life Sciences, University of KwaZulu–Natal Pietermaritzburg campus, for their professional contributions.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).