Geological and Geoelectrical Evaluation of Groundwater Pollution Status Related to Gold Mine Lechates Within Bariki and Environs, North-Central Nigeria

Abstract

Groundwater Pollution Status, related to heavy metal leachates from gold mine tailings, was investigated in Bariki and environs. It involved mapping rock outcrops, groundwater elevation, total dissolved solids (TDS), electrical conductance (EC), acidity – alkalinity level (pH), heavy metal concentration, and electrical resistivity sounding. Heavy metals’ composite contribution status was ascertained with metal pollution index (MPI). The rock outcrops are gneiss, schist, amphibolite, quartzite, and granite. The main TDS Plume exists in vicinity of active mine site 6. Subsidiary plumes exist within neighborhood of abandoned mine sites 1 and 2. The plume. diminishes southward in direction of the groundwater flow. Highest EC value exists around main TDS plume. Other high TDS values occur around subsidiary plumes. The pH is lowest in vicinity of main plume. Highest PH value within lowest TDS area indicates regolith adsorption in an alkaline environment. Largest concentrations of Co (0. 42 ppm), Cr (3.4 ppm), Cd (0.22 ppm) and Ni (0. 7 ppm) associates with main TDS plume, highest EC and lowest pH within neighborhood of active mine 6. Very high concentrations of Cd and Ni also exist within neighborhood of abandoned mine site 2. Regolith resistivity is lowest around mine sites 1, 2 and 6. It is highest within Latitudes N09 °29 '10'' to N09°29'24'' and Longitudes E06 31' 30.0'' to E06 31'48.0'', where TDS and ionic concentration are lowest. This Implies regolith resistivity is inversely related to TDS and ionic concentration. The groundwater overshot globally recommended concentration of Co, Cr, Cd and Ni in potable water. Computed MPI is 2.004, which indicates elevated heavy metal concentration. This reveals that groundwater is polluted due to heavy metal leachates from mine tailings.