Gross Alpha and Beta Radio Activity Concentrations and Estimated Committed Effective dose to the General Public Due to Intake of Groundwater in Mining Areas of Plateau State, North Central Nigeria

Abstract

Tin mining activities carried out in parts of plateau state from the beginning of this century to the early 1980’s have left behind a post mining environment scarred by numerous mine pond and uncontrolled heaps of mine tailings containing radioactive minerals that have found their way into the natural water resources. In this study the gross activities of the alpha and beta emitting radionuclides present in the naturally occurring water bodies in the mining areas of plateau state covered by Naraguta sheet 168 were determined. Fifty-eight (58) groundwater, comprising of twenty-three (23) borehole and thirty-five (35) locally dug well samples were drawn randomly. The samples were analyzed and counted for gross alpha and beta activities using MPC-2000-DP. The results showed that the range of alpha activity varied from (0.110-1.580)Bq/l with a geometric mean of 0.328 Bq/l for borehole samples and (0.010-12.590)Bq/l with a geometric mean of 0.498 Bq/l for well water samples. The range of beta activity varied from (0.012-2.760) Bq/l with a geometric mean of 0.198 Bq/l for borehole water samples and (0.020-14.640) with the geometric mean of 0.366Bq/l for well water samples. Most of the samples show higher concentration above the WHO guideline value of 0.5Bq/l for alpha activity and 1.0Bq/l for beta activity. The annual committed effective (CED) to infants, children and adults were estimated. The results shared elevated values in most of the location above the ICRP acceptable standard of 0.1mSv/yr. The mean values of CED due to intake of borehole water for alpha activity are 0.240mSv/yr, 0.481mSv/yr and 0.885mSv/yr for infants, children and adult respectively. For beta activity the values are 0.201mSv/yr, 0.410 mSv/yr. and 0.820 mSv/yr. In the well water samples the mean CED value for alpha activity are 0.485 mSv/yr, 0.963 mSv/yr. and 1.938mSv/yr for infants, children and adults respectively and for beta activity the mean values are 0.594 mSv/yr., 1.187mSv/yr. and 2.375 mSv/yr. respectively. These values show that the general public in these locations are committed to higher dose above the standard values and long term exposure could pose health threat.

Keywords: Gross alpha, gross beta, Mine tailings, water, Radionuclides