Evaluations of Groundwater Quality using Principal Component Analysis and Associated Multivariate Techniques: A Case History in Ewekoro Communities, South-West Nigeria

Abstract

The quest for quality water consumption is comprised of integration of numerous techniques from different professionals whose contributions go a long way in determining overall health status and wellness of any given society. The water quality status of boreholes in Ewekoro communities of Ewekoro Local Government Area, South-West Nigeria was investigated in this work. Water samples were collected from 25 boreholes at various sampling stations across the study area. Standard analytical water quality methods using Inductively Coupled Mass Spectrometry (ICP-MS)/Optical Emission Spectrometry (ICP-OES) and Pour Plate Techniques were respectively employed in the laboratory for the samples’ geochemical and bacteriological analyses. The raw data were processed and analyzed using Principal Component Analysis and other multivariate techniques with Excel and SPSS 20.0 statistical software packages with the corresponding outcomes systematically compared with water quality standards. For the PCA, the varimax rotation converged in 23 iterations with 6 components extracted which accounted for 92.76% of the total cumulative variance respectively observed for geochemical parameters. Na2+, K+, Ca2+, Cl-, SO42-, NH4+, PO43-, and HCO3-, Mg3+, Cu2+, Cd2+, Zn2+, Ni, S , Si, Fe3+, NO3− and Al3+ played a significant contribution with higher factor loading supported by the dominance of HCO3− among the water quality determinants. The rotation converged in 8 iterations with 3 extracted components that accounted for a total cumulative variance of 90.99% % with pH, TEMP, EC, BOD, TS, TURB, ALK, TH, TDS, THC, and DO in the Physico-chemical Parameters series. Most quality determinants in the sampled water are within allowable limits of the approved water quality standards including WHO except Alkalinity, HCO3−, MgCO3−, Cl−, BOD, Cd2+, Fe3+ and Zn2+. The overall ionic dominance pattern follows the same trend K+ >Na2+ > Fe3+ >Mn2+ and Cl- >NO3- >NO2-. The results of the microbial analyses revealed the highest Total Coliform Count of 17 x 102 MPN/100 ml while that of THBC and FCC were reported as 7.8 ×102 cfu/ml and 1.2×102 cfu/ml respectively. The hygienic status of the water sources was found to be poor. High BOD, Coliform Count and BOD5:NO3- ratios of 248.23 recorded for the groundwater samples were suggestive of possible organic pollution due to faecal invasion with the lowest measured depth of 35m. Multivariate statistical approaches namely Correlation, Principal Component Analysis and Descriptive statistics simplified and identified the interrelationship among the analyzed physicochemical parameters and the pollution sources. This study has therefore revealed that boreholes in Ewekoro were polluted and posed potential risk to biomedical safety and overall human health. Intervention measures are therefore necessary to safeguard the inhabitants from water-related diseases and their consequences.