Laboratory study of PH buffering system of landfill leachate contaminated aquifer materials

Introduction of landfill leachate into an aerobic aquifer leads to a variety of pH buffering reactions between dissolved chemical species and aquifer sediments, which play profound effects on the behaviors of contaminants beneath and down gradient from the landfill. The specific objectives of this study were to determine the spatial and temporal variations of pH and redox buffering capacity of landfill leachate polluted aquifer sediments; to identify contributions of the principal oxidized or reduced species to the pH and redox buffering capacity. The experimental results indicated that the calculated pH buffering capacity (pHBC) of uncontaminated aquifer material were 212.5 mmol/kg·pH^-1, therein, carbonate buffering capacity (CBC), silicate buffering capacity (SBC), cation ions exchange buffering capacity (CIEBC), aluminum buffering capacity (ABC) and ferric hydroxides buffering capacity (FHBC) was account for 3.1%, 8.85%, 13.6%, 23.01% and 51.44% of total pHBC, respectively. The total pHBC was decreasing with the progressive development of the pollution.