Radiological Impact of a Municipal Solid Waste Dumpsite on Soil and Groundwater Using 2-D Resistivity Tomography and Gamma Ray Spectroscopy

Abstract

The radiological impact of a municipal solid waste dumpsite on soil and groundwater in Port Harcourt municipality was investigated by integrating 2-D resistivity imaging and gamma-ray spectroscopy. The objectives of the study were to determine the lateral and vertical limits of leachate contamination and to evaluate the radioactivity concentrations in soil and groundwater. Results show that the soil and ground water have been contaminated by dumpsite emissions and radioactive materials throughout the dumpsite area. The distribution of the contaminations is uneven and spotty, both horizontally and vertically, and has penetrated to depths exceeding 31m into the ground water aquifer. The primary contaminants found in the site were leachate, waste gases, and the radionuclides of 40 K, 226 Ra, and 228 Ra. The mean absorbed dose rates of 31.98nGy/hr, 10.51nGy/hr and 6.98nGy/hr, and mean dose rate equivalents of 0.28mSv/yr, 0.09mSv/yr and 0.06mSv/yr were obtained for the soil, leachate and groundwater samples, respectively. The mean absorbed and equivalent dose rates in the soil and water samples were greater than their controls, suggesting that the dumpsite area is contaminated. These results are comparable to those reported for other waste sites in the area and lower than the maximum permitted limits for the general public of 1mSv/yr and 0.1mSv/yr for soil and water, respectively. These therefore, have no immediate radiological health burden on the inhabitants who depends on the soil and groundwater for their crops and potable water supply. However, with continuous consumption of crop products and intake of groundwater, increase in the activity concentration and dose rates of these radionuclides may