Author(s)

Willis Ougo Aguko, Robert Kinyua, John Gitonga Githiri

Physics Department, School of Physical Sciences, College of Pure & Applied Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.

The main aim of investigating activity concentrations together with distribution of radionuclides naturally in soil from Kargi was to evaluate radiological health hazard together with environmental radioactivity. Research shows radionuclides as one source of exposure due to radiation with detrimental effects health wise for populations found in areas considered high background radiation. After collecting 117 soil samples from the area, analysis was done in order to measure their natural radioactivities due to ⁴⁰K, ²³²Th and ²²⁶Ra radionuclides. Measurements method of gamma spectrometry employing a high purity germanium (HPGe) detector was employed basically to evaluate the radiological hazard of radioactivities. For ⁴⁰K, ²³²Th and ²²⁶Ra, mean calculated activities were 353.19 ± 110.07, 7.98 ± 3.98 and 7.37 ± 2.60 Bq·kg ^-1 respectively. Mean values of absorbed and effective dose rates, external and internal hazard indices together with radium equivalent activity were 23.82 ± 6.59 nGy·h ^-1 and 0.14 ± 0.04 mSv·y ^-1, 0.12 ± 0.03 and 0.14 ± 0.04 and 45.90 ± 12.65 Bq·kg ^-1 respectively. Comparing with approved global values, the values were found to be below the given global limits. Evidence of involvement of metasomatic activity of the radioelements or fractionation during weathering is seen as calculations give a higher value Th/U. Excess cancer risk, calculated from the samples showed lower values as compared to global standard values hence minimal chance of getting cancer disease. The area is safe from cancer causing radionuclides.

Kargi-Marsabit, Nuclear Science, Gamma-Ray Spectrometry, Lifetime Cancer Risk, Activity

Aguko, W. , Kinyua, R. and Githiri, J. (2020) Natural Radioactivity and Excess Lifetime Cancer Risk Associated with Soil in Kargi Area, Marsabit-Kenya. Journal of Geoscience and Environment Protection, 8, 127-143. doi: 10.4236/gep.2020.812008.