ASSESSMENT OF LEACHATE CONTAMINATION OF GROUNDWATER AROUND IGHENRE EKOTEDO DUMPSITE, OTA , SOUTHWEST NIGERIA

Abstract

The study was initiated at the instance of the Local Authority, to evaluate the physico-chemical param-eters (quality) of groundwater used by residence living around the Igbenre Ekotedo dumpsite. Nine (9) groundwater samples were collected randomly from boreholes around the dumpsite and were an-alysed for heavy metals including Fe, Pb, Mn, Cu, Cr, and Zn, using Atomic Absorption Spectroscopy. Other elements analysed for include Mg2+, Na+, K+, Ca2+, and anions such as PO43−, SO42−, NO3−, and Cl−.The physical properties tested for are their total dissolved solid (TDS), pH values, tempera-tures, hardness and electrical conductivity (EC). The results showed that the TDS, NO3−, hardness and EC concentrations of the water samples fell below the permissible limits set by the WHO standards for drinking water quality for the area except at location BH 3, BH 4 and BH 5. The concentrations of Ca2+, Na+, Cl−, SO42−, Zn and Cr are found to be below the WHO standard for all locations, but with relatively higher concentration values of Ca2+, and, Cl− at locations BH 3, BH 4 and BH 5. Also, the concentrations of PO43−, Mg2+, K+ and Fe are significantly higher than the prescribed WHO standard but with relatively higher values of Mg2+ and Fe associated with locations BH 3, BH 4 and BH 5. The spatial distribution maps of the examined parameters show a general increase in concentration towards the Southwest and Southern directions of the study area. This implies the likely direction of groundwater flow around the area since contaminants are usually mobilised and moved in the direction of groundwater flow. At the moment, the contamination is localised and limited to the South-western part of the study area and boreholes can safely be located at the North-Western and South-Eastern parts of the surveyed area.