Preliminary Investigation of Stream Sediments Contaminations Caused by Mining Activities in Ibodi and Its Environs, S/W Nigeria Using Geological and Geochemical Assessment Approach

Abstract

Mining and related activities are sources of heavy metal contamination in streams, such as copper, zinc, cadmium, arsenic and lead . The study is focused on Ibodi, southwestern Nigeria which is located in the basement complex of Nigeria and it is to assess the stream sediments of Ibodi in order to decipher the environmental impact assessment of mining activities on the environment. A total of ten stream sediment were collected from the study area and its environs along major tributaries, air dried at room temperature, sieved with 75 micron sized sieve and analyzed in the laboratory using ICP-MS (inductively couple plasma mass spectrometry technique). The analytical results of the major elements analyses show that Iron oxide [Fe2O3] has the highest major element composition, value ranging from 2.36% - 10.61% with an average value of 5.262%. This highest concentration of Iron oxide was found in location 1, with a value of 10.61% and this can be attributed to the underlying geology of amphibolites' in the Ibodi study area, which are known to be rich in Iron as well as magnesium i.e ferromagnesian minerals. Magnesium oxide [MgO] range in composition from 0.11% - 0.92% with an average value of 0.349%, the highest concentration was found in location 3. [Al2O3] ranges in composition from 0.83% - 4.158% with an average value of 2.109% the highest value was also found at location 3, it is the next in abundance to Iron oxide in the Ibodi study area. Potassium oxide [K2O] range in composition from 0.04% - 0.65% with an average value of 0.183%, other major oxides such as [P2O5], [TiO2], [Na2O] and [CaO] have average values of 0.109%, 0.096%,0.008% and 0.162% respectively; These values are generally low within the Ibodi study area, The analytical results for trace element geochemistry of Ibodi study area show that Vanadium [V] has a high concentrations and it range from 35.00 ppm - 202.00 ppm with an average mean value of 92.50 ppm, the highest concentration of this element was found in location 1 of the Ibodi study area. Arsenic [As] range from 0.10 ppm - 1.6 ppm with an average value of 0.644 ppm, there is a significant enrichment of Cobalt [Co] and Chromium [Cr] with concentrations ranging from 4.0 ppm - 53.50 ppm and 35.20 ppm -150.70 ppm respectively, with average mean values of 17.73 ppm and 88.78 ppm respectively; Manganese [Mn] has the highest concentration in the study area, with concentration value ranging from 86.00 ppm - 2165.00 ppm having an average value of 768.20 ppm; the highest concentration of this element was found in location 1 of the study area. [Ga], [Ni] and [Pb] show considerable enrichments within the study area with concentration values ranging from 3.10 ppm - 9.50 ppm, 5.30 ppm - 37.70 ppm and 6.75 ppm - 18.44 ppm, with average values of 6.08 ppm,19.80 ppm, 12.209 ppm respectively, Rubidium [Rb] range in concentration from 6.50 ppm - 30.90 ppm with an average value of 13.41 ppm, Strontium [Sr] has concentration values that range from 4.70 ppm - 37.20 ppm with an average value of 15.06 ppm. [Y], [Zr] and [Zn] has concentration values that range from 7.99 ppm - 21.10 ppm, 1.20 ppm - 4.00 ppm and 26.20 ppm-83.60 ppm respectively with average mean values of 15.065 ppm, 2.21 ppm and 46.58 ppm, the value of zinc [Zn] is considerably high in the study area with the highest value found at location 4 of the study area indicating some level of enrichment of this metals within the study area, also [Rb], [Y] and [Sr] show some considerable enrichments within the study area. from the study of the environmental parameter such as box plot and Geo-accumulation indexes the values of the selected trace elements are all less than 1, meaning that all the selected trace metals in Ibodi study area have values less than zero and are in the negative zone. In order to determine the pollution status of the study area, the values of the elements when compared to the Muller classes of geo-accumulation suggests that the study area is practically uncontaminated with the selected trace metals, the elements fall into the class 0 i.e. Practically unpolluted.