Groundwater Quality Assessment in Eti-Osa, Lagos-Nigeria using Multivariate Analysis

Groundwater quality in Eti-Osa was assessed. 18 water samples were collected from hand dug well and measured for 3 physical (pH, EC and TDS) and 9 chemical parameters (Ca, Cl, Fe, TH, Mg, NO₃, SO₄,TSS and Zn) after standard procedures (APHA). The results show that pH of groundwater samples indicates a neutral condition (7.01).TH was slightly hard (37.11mg/l).TDS, Fe and Mg concentrations were above the NDWQS limit of (500, 0.3 and 0.2mg/l) respectively for drinking water purpose. The Coefficient of variation shows that all the groundwater parameters with the exception of pH, Ca, Cl and Fe are highly heterogeneous. The correlation among the groundwater parameters shows that pH has a negative correlation at P<0.05 with Ca and TSS (r= -0.49).TH and Ca showed a positive correlations with Cl (r=0.51), EC (r=0.58).The factor analysis employed indicates four factors. Factor I, explains 27.73% of the total variance, with a strong positive loading on EC, TDS, Ca and a negative loading on pH. Factor II accounts for 21.35% of the total variance, and was characterized by strong positive loading of Zn and negative loading of Fe and TDS.Factor III was characterized by high positive loading of Cl and TH and accounts for 15.98% of the total variance while factor IV accounts for 14.05% of the total variance and was characterized by a strong positive loading of NO₃. The paper recommended routine monitoring and thorough treatment before consumption. The study demonstrates the effectiveness of factor analysis in assessing the hydrochemical processes of groundwater in the area.