Seasonal Assessment of Chemical Properties of Borehole Water in Enugu North Local Government Area, Enugu State, Nigeria

Abstract

This study assessed the seasonal variation in the chemical properties of borehole water from twelve sampled locations in Enugu North Local Government Area over a six-month period covering the wet season (June–August 2023) and the dry season (November 2023–January 2024). The analysis focused on key chemical parameters, including dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), chloride, sulphate, nitrate, total hardness, and total alkalinity, in order to understand the influence of seasonal changes on groundwater quality. The results clearly demonstrate that seasonality has a significant impact on the chemical composition of groundwater in the study area. Paired sample t-test analysis revealed statistically significant differences between wet and dry season values for all parameters investigated. Most parameters, including total hardness, BOD, chloride, sulphate, nitrate, and total alkalinity, recorded higher concentrations during the dry season, which can be attributed to reduced groundwater recharge, increased evaporation, and limited dilution of dissolved substances. In contrast, dissolved oxygen and chemical oxygen demand were higher during the wet season, likely due to increased recharge, surface runoff, and enhanced transport of organic and inorganic materials into the aquifer system. The observed seasonal trends highlight potential water quality concerns, particularly during the dry season when elevated concentrations of hardness-forming ions and nutrients such as nitrate may pose health and aesthetic challenges for domestic water use. These findings underscore the need for regular and season-based monitoring of borehole water quality in Enugu North LGA. Implementing appropriate groundwater protection strategies and public awareness programs will help ensure the sustainability and safety of groundwater resources in the area.