Assessment of Groundwater Quality Around Open Dumpsites in Suleja Metropolis, North-Central Nigeria Using Water Quality Index and Geospatial Techniques

Abstract

This research was conceptualized to assess the quality of groundwater around solid waste dumpsites in Suleja and its environs using Water Quality Index (WQI) rating and geospatial techniques. The study area lies between Longitudes 7°08ˊ00˝E to 7°14ˊ00˝E and Latitudes 9°05ˊ00˝N to 9°14ˊ00˝N. Geologically, the area is part of the Nigerian Basement Complex which consist regionally of Migmatite-Gneiss complex, low grade Schist Belt and the Older Granites. However, the major rock types in the area investigated are Migmatite, granite gneiss and granites of different compositions Water samples were collected from Twenty-three (23) different hand-dug wells and boreholes. The samples were analysed for the physico-chemical parameters and heavy metals. Factor Analysis was employed to analyse the information content of the water quality indicators to determine their appropriateness for indexing. The spatial distribution of the WQIs determined using Inverse Distance Weighting (IDW) interpolation procedure. Groundwater samples around the dumpsites had varying degrees of concentrations that either met or failed the NSDWQ regulatory standards. All pH results were within the permissible limits (6.5- 8.5). Conductivity values ranged from 61 to 81 µS/cm with the standard limit being 250 µS/cm while turbidity and TDS values exceeded the maximum permissible limits. All major ion values for all groundwater samples were within permissible limits of NSDWQ (2015) except chloride contents which were higher than the set permissible limit (3 mg/L) in all the samples analysed. Fe, Pb, Cd, Zn and Ni where detected were mostly above the allowable limits. The computed water quality indices at each sampled location range from 36.69 to 608.16, with an average and standard deviation of 129.3 and 181.90, respectively. These results generally indicate that the groundwater near the dumpsite are generally not of good quality. The high values obtained in some locations were due to high concentration of Ni and Pb in some of the samples. Water from these locations can be regarded as unfit for consumption and needs to be remediated to prevent further contamination.