Assessment of the radionuclide concentration levels of water and sediments along the Mara River

Gasper Kachenge, Department of Mining and Mineral Processing Engineering, University of Dar es Salaam, P. O. Box 35131, TanzaniaFollow
Abubakary Salama, Department of Mining and Mineral Processing Engineering, University of Dar es Salaam, P. O. Box 35131, TanzaniaFollow
Abdalah Kileo, Tanzania Bureau of Standards (TBS), P.O. Box 9524 Dar es Salaam, TanzaniaFollow
Furaha Chuma, Tanzania Atomic Energy Commission (TAEC), P.O. Box 1585 Dodoma, TanzaniaFollow

Section

Physical Sciences

Abstract

For many years, several factors have impacted the water quality of the Mara River, including population growth, agricultural expansion, livestock keeping, mining, and industrial activities. These factors have intensified water pollution and climate change effects around the river. While previous studies have mainly focused on assessing heavy metal pollution risks on the Mara River, this study evaluates the concentration levels of radionuclides in boreholes, water, and sediments along the river and its tributaries. Naturally occurring radioactive materials, including 226Ra, ²³²Th, and ⁴⁰K, were evaluated. A high-purity germanium radiation detector (HPGe) with a coaxial detector system coupled with Gamma Vision software was used for analysis. The Minimum Detectable Activity values (MDA) and the Measured Standard Reference values (MSR) were used as benchmarks for the measurement of radionuclide concentration levels in water and sediments, respectively. The results show that the activity concentration of ²²⁶Ra in the Mara River water and its tributaries exceeded the MDA value of 0.37 ± 0.10 Bq L⁻¹, while ²³²Th was not detected. In borehole water, the activity concentrations of ⁴⁰K, ²²⁶Ra, and 232Th were observed to be above the MDA values of 0.37 ± 0.1 Bq L⁻¹, 0.16 ± 0.07 Bq L⁻¹, and 0.27 ± 0.03 Bq L⁻¹, respectively. For sediments, the concentration of 226Ra was above the MSR of 18.9 ± 0.71 Bq kg-1. The concentrations for 40K and 232Th were observed to be below the MSR of 418.8 ± 13.7 Bq Kg-1 and 429.4 ± 12.9 Bq Kg-1, respectively. Based on the results, it was revealed that there was a presence of radionuclides in water due to higher concentration levels of 226Ra, 40K, and 232Th, while in sediments, only 226Ra was above the limit. The findings are instrumental in developing mitigation strategies to minimize health risks associated with radionuclide exposure, ensuring the long-term sustainability of the Mara River as a vital water resource. The data generated from this study provide a valuable tool for environmental management planning and policymaking aimed at reducing health risks linked to radionuclides.

Recommended Citation

Kachenge, Gasper; Salama, Abubakary; Kileo, Abdalah; and Chuma, Furaha (2026) "Assessment of the radionuclide concentration levels of water and sediments along the Mara River," Tanzania Journal of Science: Vol. 52: Iss. 3, Article 1.
Available at:https://doi.org/10.65085/2507-7961.2133