Assessment of heavy metals and radioactivity of the soil around titanium mining in Kinondo area, Kwale county.

Abstract

Mining is the process which involves extraction of minerals and geological materials from the earth. This activity may have a detrimental effect on the environment hence impact health of animals and human. The concentrations of the naturally occurring radioactive materials (NORM) in mineral concentrates, products increases during processing of minerals. The main aim of this study was to assess the concentration levels of heavy metal and radioactivity levels of soils in Kinondo area which is 2.86 kms from Ti mining plant in Kwale. A total number of eighty-four (84) samples were collected from twenty-eight sampling points. The points were randomly identified and three samples collected from each point consisting of top soil (0-20 cm), subsoil 1 (20-30 cm) and subsoil 2 (between 30-50 cm). The samples were collected from the three depths since concentration of the heavy metals vary vertically in different soil profiles. Energy Dispersive x-ray fluorescence (EDXRF) was used to analyze the soil samples for heavy metals. The radioactivity levels were determined using the Gamma ray spectrometry, using High Pure Germanium detector. The concentrations of levels of activity of the radionuclides U-238, K-40 and Th-232 in the soil samples were identified and measured. Gamma index, Radium equivalent, external hazard and internal hazard radiological risk parameters were therefore used to assess the radiation hazards for the heavy metal measurements, Ti, Fe, Mn, Zn and Pb were analyzed in the soil samples. The major elements were determined to be Fe (0.5–8.5 %), followed by Ti (0.3–1.5 %). All other elements had concentration values below 0.01%. Ti was determined in all soil samples at a concentration range of 0.3 to 1.5%. The high concentration of Ti may lead to competition with Fe for proteins hence leading to Ti phytotoxicity Mining may lead to elevated levels of Ti and Fe in the soil. The radioactivity levels recorded for the soil samples were used in assessing the radiological risks pose to residents. The levels of radiation were used to measure the radiation hazard that the people living in areas around the mining plant were exposed to. The results from this study will be used as reference to monitor the environmental impact of the titanium mining activities. According to the results of this study, mining activities of titanium do not lead to elevation of the heavy metals levels and radioactivity levels in Kinondo area.