Natural and artificial radioactivity levels in sediments along the Kenyan coast

Abstract

Exposures to various components of the natural background radiation in Kenya were estimated using measured activity concentrations of natural radionuclides and conversion factors. Contributions to the total effective dose include: 0.1 to 2.0 mSv.y -1 from terrestrial gamma radiation; 0.2 to 0.7 mSv.y -1 and a per capita of 0.4 mSv.y -1 from cosmic radiation; and 0.4 to 6.0 mSv.y -1 from inhalation of radon ( 222 Rn). Radon concentrations also range from 5 to 1200 Bq.m -3 in indoor air and from 1 to 410 Bq.1 -1 in drinking water. Considering the population distribution in relation to living habits of the people and to the relief and the geology in Kenya, it is concluded that the average annual effective dose in Kenya is higher than the global average. Ingestion of volcanic ash by some people, particularly pregnant women, was also identified as an additional (unusual) internal exposure pathway.

Estimation of annual effective dose and radiation hazards due to natural radionuclides in Mount Homa, southwestern Kenya

“…Gamma spectroscopy was used to determine the activities of 40 K, 226 Ra and 232 Th with a p-type intrinsic hyper pure germanium (HpGe) coaxial detector mounted vertically and coupled to a 3 kV digital high-voltage source. The HpGe detector was calibrated for energy and relative efficiency using calibration sources containing 133 Ba, 22 Na, 137 Cs, 54 Mn and 60 Co. A performance test using IAEA (15) standard reference material Soil-375, RGU, RGTh and RGK was used for checking the efficiency of the calibration of the system as done by Mustapha (11) , Hisham (12) and Achola (13) .…”

“…In Kenya, previous works have shown both low and high levels of environmental radioactivity as reported by Mustapha (11) , Hashim (12) and Achola (13) , who have determined the radionuclide content of NORM in building materials and radiation dose rates. In this study, the authors have determined the activity levels of radionuclides in rock and soil around Mount Homa area in southwestern Kenya.…”

Radioactivity in Surface Soils Around the Proposed Sites for Titanium Mining Project in Kenya

“…[10], and from Gazi [8] near the area being surveyed in the present study (Figure 1). ) is less than 50% of the global population-weighted average [10] and it is likely to be less than the country (Kenya) average, judging from results of similar surveys carried out in other parts of Kenya, e.g. Mustapha et al [7].…”

“…Detailed description of the gamma-ray spectrometer setup as well as the detector calibration procedures using the IAEA reference materials (RGU-1, RGTh-1, and RGK-1) are presented in earlier reports [7][8][9].…”

Coastal Waters

“…Potential pollution from the export processing zone, industries and mining has not been recorded, although these are activities that contribute to pollution of the coastal waters as the industries discharge untreated solid and liquid effluents into the sea (Government of Kenya, 2009Kenya, , 2010Hashim et al, 2004).…”