INVESTIGATION OF THE CONCENTRATIONS OF POTENTIALLY TOXIC ELEMENTS IN GROUNDWATER WITHIN BARIKI AND ENVIRONS, NORTH CENTRAL NIGERIA

Abstract

An integrated geological, geo-chemical and geophysical studies were carried out to investigate the concentrations of potentially toxic elements in groundwater within Bariki and environs, North Central Nigeria, in order to ascertain the effect of mining on the water quality. The investigation involves surface geological mapping of Bariki and environs on a scale of 1:12,500, groundwater level mapping, Determination of toxic elements concentration using Atomic Absorption Spectroscopy (AAS) and geo-electrical sounding. The lithology at every outcrop was identified on the basis of textural and visual inspections of mineral composition using hand lens and further refined by petrographic examination which reveals that the area studied is dominantly schist, granite and amphiboles schist, other rock bodies includes gneiss, quartzites and localized muscovite schist. The groundwater level mapping (Surface water level, depth of the well and elevation above sea level) were recorded. Hydraulic head of each well was calculated and the groundwater flow map was also generated indicating NW, SE and SS flow directions. The physical parameters measured in-situ were Temperature (T), pH, Electrical Conductivity (EC) and Total Dissolved Solid (TDS) using a multifunctional TDS/EC/pH/TEMP water quality meter tester, pH shows slightly low values of 6.22, 6.24 and 6.31 at BKW L2, BKW L3 and BKW L5 when compare to WHO and NSDWQ standards. Out of the ten toxic elements analysed, Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Nickel (Ni), Zinc (Zn) and Arsenic (As), only Cadmium 0.075 ppm, Manganese 0.73 ppm, Lead 0.037 ppm and Iron 22.71 ppm were found to be above WHO and NSDWQ standard. Computed Metal Pollution Index (MPI) of 135.5002 indicates the groundwater is highly polluted from multi-metal effect. The subsurface apparent resistivity decreases in both NW and SE direction of groundwater flow. An active mine site upsets the NW, SE and the resultant SS decrease in heavy metal concentration. This implies that groundwater pollution in Bariki and environs is attributed to mining activities.