Hydrogeochemical Evaluation of Groundwater Quality Across Seasonal Periods in Lagos State

Groundwater is a critical resource for domestic, agricultural, and industrial purposes in Lagos State, Nigeria. However, its quality is increasingly threatened by anthropogenic activities and seasonal dynamics. This study investigates hydrogeochemical variations between the wet and dry seasons across multiple land-use zones, including urban, agricultural, and industrial areas, to assess the seasonal impact on groundwater quality. Physicochemical parameters, such as pH, electrical conductivity (EC), and total dissolved solids (TDS), alongside concentrations of heavy metals including arsenic, cadmium, chromium, copper, nickel, lead, and mercury, were analyzed. Seasonal fluctuations were found to significantly influence groundwater chemistry: limited recharge during the dry season intensified pollutant concentrations, while heavy rainfall during the wet season promoted infiltration of contaminants from agricultural runoff and waste disposal sites. Health risk assessment using Estimated Daily Intake (EDI) and Hazard Quotient (HQ) models indicated potential exposure risks associated with prolonged consumption of contaminated groundwater, particularly for vulnerable populations. The study highlights the need for seasonally-informed groundwater management strategies to mitigate contamination and safeguard public health. These findings provide valuable insights for policymakers, water resource managers, and environmental stakeholders seeking to ensure sustainable and safe groundwater use in Lagos State