Assessment of groundwater quality in Eti-Osa LGA, Lagos- Nigeria
Abstract
The rapid population growth and the accelerated pace of industrialization have effect on groundwater quality as a result of its overexploitation and improper waste disposal, especially in urban catchment. Water Quality Index (WQI) is one of the most
effective tools to communicate information on the quality of water to concerned citizens and policy makers. In this study, 18 locations were selected within the urban catchment using random sampling technique. The water samples were collected and analyzed for physico-chemical parameters including pH, Total Hardness, Calcium, Magnesium, Chloride, Nitrate, Sulphate, Total Dissolved Solids and Iron using standard procedure. The sampling locations were determined with GPS and interpolated on digitized topographical map of the study area. The 9 parameters were used for calculating Water Quality Index within the study area. The result show that, the groundwater quality ranges between 0.86 and 1,228.0mg/L. Total Dissolve Solid has the highest mean (607.44mg/L), followed by Cl (222.22mg/L) while Fe has the least value of (0.66mg/L).Further analysis revealed that, all the parameters examined except (pH, Ca, Cl and Fe) show high variation. Statistically significant positive correlations was observed between Total Hardness and Chloride (r =0.51) while negative correlation was observed between pH and Calcium (r = - 0.49) at p < 0.05.The computed WQI for the samples ranges from 26.62 to 24,345.0. The high value of WQI has been found to be mainly from the higher values of pH, Magnesium, Chloride, Total Dissolved Solids and Iron. About 98.77% of water samples in the study area are unsuitable for drinking while 0.17%, 0.28% and 0.77% are excellent, good and very poor respectively. The study recommended thorough treatment of the groundwater before consumption in the study area.