Abstract

Waste management has become a major environmental challenge worldwide, particularly due to the rapid increase in solid waste generation associated with population growth and socioeconomic development. The accumulation of waste in landfills leads to the production of leachate, a highly contaminated liquid that poses serious risks to soil and groundwater. This study investigates the impact of the Hassi Bounif Technical Landfill, located in Oran, northwestern Algeria, on the physicochemical quality of nearby groundwater. Leachate and groundwater samples were collected during both summer and winter seasons and analyzed for physicochemical parameters and heavy metals using standard analytical methods. The leachate exhibited high contamination levels, with mean concentrations of Fe (17.55 mg/L), Pb (0.85 mg/L), and Cu (3.00 mg/L), while the average levels of Al, Cr, Mn, Hg, Ni, Cd, Mg, and Zn were 5.00, 1.25, 3.50, 0.04, 0.85, 0.60, 4.00, and 5.50 mg/L, respectively. Elevated organic loads were also recorded (COD = 28,653 mg/L; BOD5 = 6223 mg/L), resulting in a leachate pollution index (LPI) value of 33.94, indicating a high pollution potential. Groundwater samples collected near the landfill showed electrical conductivity ranging from 3536 to 7905 μS/cm and elevated concentrations of major ions (Na+, Ca2+, Mg2+, Cl−, and SO42−), exceeding both World Health Organization (WHO) and Algerian standards. A distinct gradient was observed, with contamination levels decreasing with distance from the landfill. Seasonal variations were evident in both leachate and groundwater quality, with higher pollutant concentrations during the summer season, primarily due to enhanced evaporation and reduced groundwater dilution. The findings confirm the significant influence of landfill leachate on groundwater quality in the study area and underscore the urgent need for improved leachate treatment and management practices to mitigate environmental and public health risks in semiarid regions such as Oran.