Environmental Impact of Mining and Pedogeochemistry of Agunjin area, Southwestern Nigeria

Abstract

Agunjin area occurs in the southwestern sector of the Nigerian Basement Complex along Ajase Ipo-Igbaja road. The present study is to assess the environmental impact of mining and the extent of contaminations in the soil. Soil samples were collected at a distance of about 100-400metres in N-S and E-W direction to the mining phase in Agunjin area. Twelve Soil samples were analyzed for major oxides and trace elements using Atomic Absorption Spectrometry (AAS). The major element compositions of Na2O ranges from 0.26 to 0.50wt%, K2O ranges from 0.21 to 0.47wt%, Al2O3 varies from 0.85 to 1.50wt%, MgO varies from 1.51 to 2.83wt%, CaO ranges from 15.39 to 55.97wt%, Fe2O3 and MnO ranges from 0.087 to 0.28wt% and 0.093 to 0.14wt% respectively. Results from the studies revealed that the concentration of Cu ranges from 5.49 to 27.56ppm and Zn ranges from 0.33 to 6.59ppm. The high concentrations of the CaO, Zn and Cu in the soil could be linked to the elemental concentrations in the marble and other metasedimentary rocks in the area which were mechanically dispersed by the mining activities and surface erosion. These elements will eventually find their way into the drainage system leading to some contaminations and possibly bioaccumulations. Total environmental impact score of mining in the area is (-) 3850 indicating major injurious impact on environment and the excess of Mn in soil is hazardous to the people living in the area