Physicochemical and geochemical analysis of groundwater quality in Ilaporu, Ogun State, Nigeria, for domestic and agricultural usage

Abstract

The inhabitant of Ilaporu settlements solely depends on groundwater for domestic and agricultural purpose as a result of scarcity and contamination of surface water. The present study therefore aimed at investigating the physicochemical and geochemical composition of Ilaporu groundwater for domestic and agricultural suitability. Hand-dug well waters were picked randomly from thirty (30) major agricultural settlements with the aid of Global Position Satellite (GPS). The physical parameters such as Hydrogen ion concentration (pH), Electrical conductivity (EC),) and Total Dissolved Solid (TDS) were measured in-situ while the chemical compositions of cations (Ca²⁺, K⁺, Mg²⁺ and Na⁺) and anions (${\mathrm{Cl}}^{-}$, $F^{-}$, ${\mathrm{SO}}_4^{2-}$, ${\mathrm{NO}}_3^{-}$and ${\mathrm{CO}}_3^{2-}$) were obtained through laboratory procedure. The water was subjected to an analytical measurement utilizing an Atomic Absorption Spectrometer (AAS) to examine seven heavy metals (Cd, Pb, Ni, Fe, Mn, Co, and Zn). This study was conducted to examine various water geochemical pollution and contamination indicators, including degree of contamination (DoC), modified degree of contamination (mDoC), enrichment factor (ER), accumulation index (Igeo), pollution loading index (PLI), ecological risk potential (ERIP), and health risks related to carcinogenic and non-carcinogenic substances. Water quality indexes such as the permeability index (PI), sodium adsorption ratio (SAR), soluble sodium percentage (SSP), sodium percentage ratio (%Na), residual sodium carbonate and bicarbonate (RSC and RSBC), Kelly's ratio (KR), and magnetic ratio (MR) were also used to evaluate the suitability of the water for irrigation. The geochemical result obtained revealed that the water has no trace of lead (Pb) contamination while other heavy metals obtained are within the acceptable limit of WHO and NSDWQ, except cadmium. The water quality index (WQI) was obtained to range between 1.11 and 23.76%. The result implies that the water falls in the excellent categories of the water quality index, thereby making it suitable for both domestic and irrigation. The PLI, DoC and mDoC water contamination/pollution index revealed PLI <1, DoC <7 and mDoC <1.5 in all analysed water samples. This implies that the water has little or no contamination. The health assessment result showed that the water samples in the study area are susceptible to non-carcinogenic risk while Cd and Ni increase the risk of cancer (carcinogenic). The irrigation suitability of the groundwater are 100%, 100%, 93.7%, 60%, 83.3%, 83.3%, 86.7% and 90%, for PI, SAR, %Na, MR, RSC, RSBC, KR and SSP, respectively. It is therefore recommended that the water quality assessment should be carried out at least once every three years in order to minimize any potential health hazards, contamination, and appropriateness for irrigation.