Gamma Ray Spectrometric Analysis of Sand Samples from Selected Beaches along Kenyan Coastline.

In this study, the activity concentration levels of 238U, 232Th, and 40K in sand samples collected from Shanzu, Nyali, Kenyatta, Tiwi, Shelly, and Diani beaches selected along the Kenyan coastline were determined using a gamma ray spectrometer with a NaI(Tl) detector. The average activity concentrations of 238U, 232Th, and 40K in sand samples were analyzed as 87 ± 4, 98 ± 4, and 1254 ± 62 Bq/kg, respectively. Also, radium equivalent (Raeq) activity and internal (H in) and external (H ex) hazard index were calculated to assess the radiological hazards associated with the use of sand samples as building materials. The average values of Raeq, H in, and H ex were found as 327 ± 16 Bq/kg, 0.98, and 0.72, respectively. The average values of outdoor and indoor annual effective dose rates were estimated as of 0.23 and 0.63 mSv/y, respectively, which are below maximum recommended limit of 1 mSv/y. Generally, these results indicate no significant radiological health hazards for the studied beaches.

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

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.