Validity of Tin Mine Stream Sediments in the Construction of Residential Homes

I.Y. Zakari,T.C. Akpa,.G.E. Ibeanu

doi:10.19026/rjees.5.5732

Abstract

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 40 K, 226 Ra 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 40 K, 226 Ra and 232 Th 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.

Highlights

Nigeria, in the twentieth century, was one of the world’s major tin producing countries but production later faced a decline towards the end of the century
Considering the posed potential health risk to residents and other members of the public in general, this study addresses the issue of utilization of the tin mine pond sediments for making bricks used in building residential homes through evaluation of its Naturally Occurring Radioactive Materials (NORMs) contents
Calculation of radiological effects: Three radiological models were employed in the assessment of the radiological effects: annual effective dose (HE), radium equivalent dose (Raeq) and the external hazard index (Hex) due to specified radio nuclides 226Ra, 232Th and 40K

Summary

Introduction

In the twentieth century, was one of the world’s major tin producing countries but production later faced a decline towards the end of the century. This did not imply that tin mining activities ceased completely in the mining areas. Tin mining produces tin tailings, a by-product of rough concentrates of cassiterite. These tailings from tin mining industry were usually processed to extract valuable minerals such as columbite, ilmenite, monazite, zircon, xenotime and struverite. There is a combination of both radiological and chemical toxic elements associated with tin mining processing activities (Ibeanu, 2003)

Methods

Results

Conclusion