Assessment of Levels of Natural Radioactivity in Sand Samples Collected from Ekalakala in Machakos County, Kenya

Abstract

Construction sand is naturally polluted with radionuclides of terrestrial origin. In this study, specific activities of 238U, 232Th, and 40K in 30 sand samples collected along the Ekalakala River, Machakos County, Kenya, were measured using a high-purity germanium γ-ray spectrometer. The specific activities ranged between 9.7 Bqkg−1 and 24.0 Bqkg−1, 11.5 Bqkg−1 and 26.2 Bqkg−1, and 820 Bqkg−1 and 1850 Bqkg−1 for 238U, 232Th, and 40K, respectively. While the mean specific activities for 238U and 232Th were less than half of the world average values of 33 Bqkg−1 and 45 Bqkg−1, respectively, the average specific activity of 40K was significant since it was three times the global mean value of 420 Bqkg−1. A calculated absorbed radiation dose rate for the sand varied between 46.8 nGyh−1 and 94.2 nGyh−1 with a mean of 68.5 ± 13.3 nGyh−1. This is not significantly different from the world average dose rate of 60 nGyh−1 for geological samples. The AEDR and Hex had maximum values of 0.29 mSvy−1 and 0.52, respectively, both within the recommended limits of radiation exposure for members of the general public. Based on these results, the sand from Ekalakala River does not pose significant health implication to the sand harvesters as well as the inhabitants of the houses constructed using this sand.

Natural Radioactivity in Soil and Bitumen in Al-Marj Spring and Abu-Jir Village, Anbar, Western Iraq

“…4. 232 Th has a good positive correlation with 40 K (r= 0.89), that be owing to the fact the radionuclides develop from the same rock formation (Munyao et al, 2020), which is illite due to potassium in its structure as the main constitute. While 226 Ra has a poor positive correlation with 232 Th and 40 K, that means the source of 226 Ra from ascending fluids as a result of its high mobility, that transport 226 Ra from source rock and adsorption on clay minerals and organic matter.…”