Assessing Water Quality and Health Risks of Potentially Toxic Elements in Oued Inaouen and Its Tributaries near Taza City, Morocco

Abstract

Water contamination from uncontrolled landfills is a critical environmental and public health challenge in developing regions. This study evaluates the physicochemical, bacteriological, and metallic (trace elements) pollution of surface and groundwater in the Oued Inaouen watershed near Taza, Morocco, specifically assessing the impact of landfill leachate. Eight stations (six surface and two groundwater) were monitored during three campaigns (March 2020, May 2021, and May 2022). Analysis covered nutrients, organic matter (BODs, COD), heavy metals, and microbial indicators. Water quality was quantified using WQI, CPI, HPI, and MI indices alongside carcinogenic and non-carcinogenic human health risk assessments. Results reveal significant deterioration downstream of the landfill, with Mn, Al, Fe, and As concentrations frequently exceeding WHO guidelines. Pollution indices confirmed severe contamination at sites O2, O4, and O6. Furthermore, the Hazard Index (HI) exceeded safe thresholds, particularly for children, while carcinogenic risks for Cd, Ni, As, Cr, and Pb surpassed the 10 -4 limit. These findings highlight an urgent need for improved waste management and remediation strategies to protect local ecosystems and public health.