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.
Highlights
Sand mining is a well-known and booming economic activity in various regions of Kenya such as Machakos County [1]. is is as a result of the rapid economic expansion in most of the neighbouring cities and towns such as Nairobi, ika, and Machakos, which has in turn resulted in an increased demand for the commodity in the construction industry
Despite the continued harvesting and use of the construction sand from Ekalakala, there is no information about the radioactivity levels of the sand and possible health effects associated with continuous exposure of the sand harvesters as well as inhabitants of houses built using this sand
In Kiambu County, River ika combines with River Sagana to form River Chania in ika which in turn stretches to River Ianguni in Machakos County and to Ekalakala River which pours its waters into Masinga dam
Summary
Sand mining is a well-known and booming economic activity in various regions of Kenya such as Machakos County [1]. is is as a result of the rapid economic expansion in most of the neighbouring cities and towns such as Nairobi, ika, and Machakos, which has in turn resulted in an increased demand for the commodity in the construction industry. Sand mining is a well-known and booming economic activity in various regions of Kenya such as Machakos County [1]. 238U 232Th 40K Figure 1: Comparison of the specific activity of 238U, 232 , and 40K obtained in this study with values obtained in other parts of Kenya and the world. E results from this study seeks to provide knowledge and data on exposure levels associated with radionuclides in the construction sand and avail the baseline information for future monitoring of the construction sand. This study acts as an eye opener to both the residents and local authorities to know that sand harvesting can attract more serious implications if not well monitored
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