Hydrogeochemical assessment of groundwater of Igboora Area, Southwestern Nigeria

O.A Akanbi,O Oshin,A.G Olatunde,W Sanni

doi:10.4314/gjpas.v26i2.2

Abstract

The people of Igboora rely on groundwater for their domestic water supply. A hydrogeochemical study was carried out on twenty-seven groundwater samples collected from various boreholes across the study area to determine the suitability of the groundwater for drinking purpose. The total dissolve solids (TDS), electrical conductivity (EC) and pH of the water were measured in the field directly, while the concentrations of major ions were done in the laboratory using flame photometry and spectrophotometry methods. The hydrogeochemical facies classes was done with piper plot and the likely enrichment source(s) of the chemical facies were interpreted with Gibbs plot in conjunction with correlation analysis. The results showed that the pH was between 5.0 and 6.7 at an average (av.) of 5.8; TDS ranged from 50 – 280 (av. 183) mg/L and EC was 110 – 560 (av. 373) μS/cm. The concentrations of the major cations in mg/L were: 5 – 105.5 Ca2+, 1 – 11.9 Mg2+, 0 - 95 Na+, 0 – 112 K+, while for anions the ranges were, 9 - 58 HCO3 - , 6.8 – 28.8 CO3 2-, 1.1 – 29.4 SO4 2-, 2.9 – 26 Cl- and 16 – 90.5 for NO3 -. From the mean values, the order of the cationic dominance was Ca2+ > K+ > Na+ > Mg2+ while that of anionic was NO3 -> HCO3 - > CO3 2- > CI- > SO4 2- . The hydrogeochemical facies in the groundwater was mainly Ca-HCO3 type with minor occurrences of Na-HCO3 and Ca- Na-HCO3 types. Enrichment source of the cationic chemical facies was mainly rock dominated, while that of the anionic were from meteoric and biogenic sources. From the results of correlation analyses, the TDS has direct and positive relationships with most chemical constituents, indicating that the analysed ionic constituents dominated the dissolved solids in the groundwater. The groundwater can be said to be potable except that the water in the boreholes is slightly acidic and nitrate concentration exceeded recommended limit of 50 mg/L in many of the samples.

Highlights

Groundwater is the main source of potable water supply for domestic, industrial and agricultural purposes in developing nation like Nigeria where piped-borne water supply is no longer reliable and, in most cases, unavailable (Fashae, et al, 2014; Akanbi, 2018)
This is because the chemical constituents of groundwater are affected and modified by mineral dissolution of the host rocks, it is largely affected by direct recharge from surface effluents and chemical nature of the recharging water and interactions along soil units during infiltration of water
The total dissolved solids (TDS) which is a strong indicator of the degree of water freshness/salinity and suitability for domestic use was between 50 and 280 mg/L

Summary

Introduction

Groundwater is the main source of potable water supply for domestic, industrial and agricultural purposes in developing nation like Nigeria where piped-borne water supply is no longer reliable and, in most cases, unavailable (Fashae, et al, 2014; Akanbi, 2018). The chemical characterisation of the groundwater system is an essential investigation of any groundwater development and management scheme This is because the chemical constituents of groundwater are affected and modified by mineral dissolution of the host rocks (aquifers), it is largely affected by direct recharge from surface effluents and chemical nature of the recharging water and interactions along soil units during infiltration of water. Igboora and its environs were hit by series of water-borne diseases in the 1980s as a result of lack of potable and reliable water supply. This made the government to embark on numerous groundwater drilling project in most parts of Ibarapa region, where Igboora is one of the major towns (Akanbi, 2016).

Methods

Results

Discussion

Conclusion