Assessment of seasonal water quality variation in River Yobe, Gashua, Northeastern Nigeria

Abstract

Water pollution in rivers is a growing global concern with implications for ecosystem health, public safety, and livelihoods. This study examined seasonal variations in physicochemical parameters and heavy metal contamination of River Yobe at Gashua, Nigeria, focusing on anthropogenic influences. Stratified sampling was conducted across three activity zones fishing, irrigation, and domestic during the early dry, late dry, and rainy seasons (December 2024–August 2025). A total of 54 water samples were analyzed for temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), and heavy metals (Cd, Cu, Pb, Zn) using standard procedures. Household surveys were also administered to assess river utilization and waste disposal practices. Findings revealed that 85% of respondents relied on the river for domestic and livelihood activities, while 45% disposed waste directly into it. Physicochemical parameters showed significant seasonal differences (p < 0.05): temperature peaked during the late dry season (28.8 °C), while DO was lowest in the rainy season (4.67 mg/L). Although most values were within WHO and NESREA guidelines, DO and BOD fluctuated beyond desirable limits in some seasons. Heavy metal analysis indicated elevated cadmium (0.043 mg/L) and lead (0.107 mg/L) concentrations during the rainy season, exceeding WHO limits, while Cu and Zn remained within safe thresholds. These results highlight increasing pollution pressure on River Yobe, driven by poor waste management and seasonal dynamics. Strengthened environmental regulation and community-based interventions are essential for safeguarding water quality and sustainable use.