期刊名称：Research Journal of Environmental and Earth Sciences
印刷版ISSN：2041-0484
电子版ISSN：2041-0492
出版年度：2013
卷号：5
期号：12
页码：751-755
出版社：Maxwell Science Publications
摘要：Tin mining in the Jos Plateau, Nigeria has left the residents with a legacy of radioactively contaminated soils, polluted water supplies, scattered heaps of radioactive mine/mill residues and radioactive mine ponds/steams. The gamma radiation of sediment samples collected from the tin mine streams at Kokop, Zawan, Sabon Barki and Yelwa, which the residents used in building constructions, were measured. The samples were collected, dried under ambient temperature and sealed in plastic containers and the activity concentrations of 40K, 226Ra and 232 Th measured in the laboratory using NaI (Tl) gamma-ray spectrometry technique with an accumulating time of 30,000seconds per sample. Similarly, elemental concentration levels of the samples were determined using XRF technique. The Kokop, Zawan, Sabon Barki and Yelwa measured range of activity concentration levels for 40K, 226Ra and 232 h were (324-955) Bq/kg, (307-461) Bq/kg and (851-1203) Bq/kg; (154-267) Bq/kg, (89-157) Bq/kg and (78-111) Bq/kg; (163-322) Bq/kg, (77-108) Bq/kg and (115-208) Bq/kg and (134-379) Bq/kg, (61-109) Bq/kg and (156-198) Bq/kg, respectively. The radiation hazards associated with these natural building materials were assessed using three radiological models, namely; "Radium Equivalent", "Mean Annual Effective Dose" and "Gamma Activity Concentration Index". In each case, there was an indication that Kokop sediment samples were not safe for use in the construction of residential houses and hence poses a significant source of radiation hazards to occupants of such buildings. The Kokop's mean recorded radium equivalent, mean annual effective dose and gamma activity concentration index were 2057.7±45.8 Bq/kg, 4.6 mSv/yr and 7.0, respectively. A total of 21 elements were detected in the sediment samples. Arsenic, the element of interest, was significantly high, much higher than the recommended acceptable level in soil to be used in construction of residential houses. This further justifies the unsafe use of the sediments in the construction of dwelling homes bearing in mind the activities of pica children who exhibit the hand- to-mouth habit and may probably be co-occupants as well.
