[pH buffering capacity of geological media on landfill leachate]

The one-dimensional breakthrough soil column experiment and static experiment were constructed to investigate the spacial and temporal pH buffering capacity of the four natural geological media. Experimental results indicate that the background pH buffering capacity of fine sand, silt sand and clay is 79.9 x pH(-1) mmol/kg, 207.5 x pH(-1) mmol/kg, 456.4 x pH(-1) mmol/kg respectively. With the time going on and the distance closer to the leaching source, for each medium which is contaminated by the landfill leachate, the total pH buffering capacity decreases, the buffering capacity of calcium carbonate buffering system decreases, the buffering capacity of the silicate and cation exchange buffering system have no obvious changes, and the buffering capacity of the aluminium and ferric oxide buffering system also decrease, but the soil's buffering capacity of aluminium buffering system increases at first and then decreases. The temporal and spacial buffering capacity for each buffering system of the fine sand all increase appreciably. The order of the pH buffering capacity of the geological media on landfill leachate is fine sand < silt sand < clay < soil. The soil and clay have a good pH buffering capacity on landfill leachate as well as the controlling effect of the pollutants' transferring and diffusion.