Geochemical evaluation of soils and groundwater around upper Ekehuan Dump Site, Ekehuan Road, Benin City, Nigeria
Indiscriminate dumping of solid wastes has a major environmental and health impacts on Soils and Groundwater quality around the dumpsites which have been observed overtime to have significant deterioration. To this end, Soils, groundwater and leachate samples around Upper Ekehuan (Asoro) dumpsite on coordinates 6019’’ 20 N – 60 19’’ 40 N and 50 35’ 0’’E - 50 35’20’’E in Ovia North -East Local Area in Benin were collected in order to investigate the impact of the dumpsite on soils and groundwater. A total of twenty-two(22) samples consisting of twelve(12) soils, eight(8) groundwater and two(2) leachate samples were analyzed using Atomic Absorption Spectrophotometer(AAS) PG550model with air acetylene flame to determine the physicochemical parameters. The result revealed that the pH values of soil samples collected range between 4.98-5.43 while that of groundwater range between 5.24-5.87 indicating that the soils and groundwater are slightly acidic. The result of soil samples show that the concentration of Cd(0.69mg/kg), Cr(2.87mg/kg), Cu(1.25mg/kg), Pb, Mn and Ni(14.60mg/kg) were much lower than permissible limits of WHO standards and also that the samples collected close to dumpsites have been moderately impacted as application of environmetric treatment such as Contamination factor (Cf), Geo-accumulation Index (Igeo) and Enrichment factor (Ef) Analyses further affirms that the dumpsite affected the soils significantly. Heavy metals such as Ni(2.86-10.01mg/l), Cd(0.26-0.88mg/l), Cr(1.20-4.19mg/l), and Pb(0.49-1.73mg/l) analyzed for groundwater were observed to have concentration above the World Health Organization’s (WHO) and Nigeria Standard for Drinking Water Quality(NSDQW) maximum permissible limits. It is recommended that the water from boreholes in the residences around the dumpsites should be treated before consumption. Dumpsites should be sited far away from residential area.
Keywords: Groundwater Quality, Contamination/ Enrichment Factor, Geoaccumulation Index, WHO, NSDQW, Upper Ekehuan, Ovia North East