Evaluation of Radioactive Metals in Surface Soil from an Artisanal Gold Mining Area, Migori, Kenya

Abstract

Despite the fact that mining for gold causes serious radioactive concerns, there is a scarcity of radiological data in surface soils from artisanal gold mining area in Migori, Kenya. In this study, radioactive metals in 39 surface soil samples collected from gold mine sites were analysed using inductively coupled plasma-mass spectrometry (ICP-MS) in Bureau Veritas Laboratory, Canada. The obtained mean activity concentrations of 238U, 232Th, 137Cs, 40K and 226Ra were 11.34± 3, 25.49 ± 3, 17.27 ± 0.6, 58.25± 4.7, 25± 4Bq/kg, respectively. The estimated average of absorbed dose rate in air (nGy/h), annual effective dose (μSv/y), radium equivalent activity (Bq/kg), external hazard index, internal hazard index, and lifetime cancer risks (1/Sv) were 66.9 ± 1.1, 89.3.3 ±4.6, 129.1 ±5.1, 0.37±0.01, 0.45 ± 0.02, 2.95×10-4±1.4x10-5, respectively. The mean values of the radium equivalent activity, external hazard index, and internal hazard index were all within safe ranges. The Pearson linear coefficient was also used to examine the relationships between radionuclides in surface soil samples. At the 0.05 significance level, 238U was slightly positively associated with 232Th, 226Ra and 137Cs while at t the 0.01 level of significance, there was a substantial positive correlation between 232Th and 226Ra and 137Cs. Both 232Th and 226Ra were negatively and marginally correlated with 40K at 0.05 significance level. In conclusion, the concentrations of radioactive metals in surface soil in the artisanal gold mining region were within the normal range and may present no significant health hazards to the communities in the examined area.