Activity Concentration Levels of Natural Radionuclides in the Sediment Samples from Rosterman Gold Mine, Lurambi Sub – County, Kakamega County, Kenya

Abstract

Rosterman, located in Lurambi sub - county, Kakamega County, Western Kenya consists of gold mining that is done locally (artisanal gold mining). The activity concentration of 238U, 232Th and 40K in sediment samples from the wastes of gold mining were determined by gamma ray spectrometry using NaI (Tl) detector and decomposition of measured gammaspectra. As a measure of radiation hazard to the general population, gamma radiation dose rates were also evaluated. The average activity concentrations of 238U, 232Th and 40K were 85±2.24, 114±5.78and 260±12.18Bqkg-1, respectively. The mean absorbed dose rate in air was 52.5±4.2nGyh-1 while the annual average effective dose rate for indoor and outdoor were 0.4±0.02 and 0.3±0.01mSvy-1 respectively. The absorbed dose rate due to gamma radiation from naturally occurring radioactive materials was below the global average value of 60 nGyh-1. Hence, mining of gold at Rosterman has minimal hazardous health implicationto the general public.