ASSESSMENT OF THE IMPACT OF DUMPSITES ON GROUND WATER QUALITY IN OSOGBO METROPOLIS, NIGERIA

Abstract

The contamination of the quality of groundwater resulting from the infiltration of leachates from dumpsites have been a great concern in recent years. Consequently, this research is focused on investigating the impact of leachates from dumpsites on ground water quality by the determination of the physico-chemical properties and heavy metal contents of two well-water samples near two dumpsite and a control site in osogbo metropolis, Nigeria. The result of physico-chemical parameters are: temperature (26.1-26.3 ^oC) , pH (6.95-8.95), conductivity ( 150.3-1207 µS/cm), Dissolved Oxygen (DO) ( 5.68-7.26 mg/L), Total Dissolved Solids (TDS) (170.51-608.2 mg/L), Total Hardness (TH) (33.43-120.28 mg/L), Nitrate (1.08-7.05 mg/L) , Sulphate (12.15-39.06 mg/L), Phosphate (0.8-1.33 mg/L), Biochemical Oxygen Demand (BOD) (1.34-3.46 mg/L), Ca (25.65-72.34 mg/L) and Mg (7.78-29.28 mg/L). The result of heavy metal concentration (mg/L) are: Cu (0.75-0.93), Zn (0.90-2.25), Pb (0.01-0.03), Cr (0.05-0.12), Co (0.01-0.04), Mn (0.07-0.20), Fe (0.85-2.72), Ni (0.006-0.37), Cd (0.003-0.02). The result showed some level of infiltration of leachates from dumpsite into the water. However, many anlaysed parameters were below the permissible limit of WHO and Nigerian Standard for Drinking Water Quality (NSDWQ) with the exception of Pb, Cd, pH and TDS. Furthermore, the findings revealed the effect of variation of season on the quantity of measured parameters. Therefore, the study suggests the implementation of a well-designed leachate collection system to avert the continual contamination of underground water.