[pH buffering capacity of landfill leachate contaminated aquifer sediments in different redox zones]

A simulated column filled with fine sand was constructed to investigate pH buffering capacity of aquifer sediments and its variation in different redox zones. Experimental results indicated that background pH buffering capacity of sediments was 324.93 pH(-1) mmol/kg, and the buffering capacities of cation exchange, calcium carbonate, silicate and secondary were 41.77 x pH(-1), 86.53 pH(-1), 47.33 pH(-1) and 149.31 x pH(-1) mmol/kg, respectively. pH buffering capacity increased 12.4%, 10.8%, 19.8% and 11.1% in MGZ/SRZ, IRZ, NRZ and ORZ, respectively. Cation exchange capacity (CEC) and base exchangeable cation (BEC) content of sediments in redox zones were lower than background content which was 11.59 x pH(-1) and 8.52 x pH(-1) mmol/kg, respectively. Base cation saturation was increasing first and then then decreasing, and it was higher than background of 63.47%. Therefore, the aquifer sediments have high pH buffering capacity. Research on the pH buffering capacity of landfill leachate polluted aquifer sediments in redox zones could provide theoretical evidences for remediation of polluted sites.