[Buffer capacity of aquifer media polluted by landfill leachate].
A column filled with fine sand was constructed to investigate pH buffering capacity and redox buffering capacity of aquifer media. Experimental results indicated that calcium carbonate played a significant role in pH buffering; with the aggravating of landfill leachate pollution, the pH buffering capacity of calcium carbonate was increased; it increased from background value, which was 1.62 x pH(-1) mmol/kg, to 41.3 x pH(-1) mmol/kg. With the aggravating of landfill leachate pollution, the oxidation capacity (OXC) of aquifer media was decreased, and the reduction capacity (RDC) was increased. In unpolluted aquifer media, Fe3+ was the main component of OXC, and accounted for about 70.5% of OXC; TOC was the main component of RDC, and accounted for about 98.7% of RDC. Species of the minerals was related to the degree of pollution; large fraction of amorphous Fe3+ and part of crystalline Fe3+ were reduced near the pollution source, and the reduced product was mainly precipitated as FeCO3 and FeS. Deposit of produced Fe2+ led to ion-exchangeable Fe2+ content increased from 0.5% of uncontaminated aquifer media to 3%. Therefore, Fe3+ may act as a very significant redox buffer in aquifer.
Dong
Jun
J
College of Environment and Resources, Jilin University, Changchun 130026, China. dongjun@jlu.edu.cn
Zhao
Yong-Sheng
YS
Liu
Ying-Ying
YY
D001673:Biodegradation, Environmental; D002119:Calcium Carbonate / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D012037:Refuse Disposal / Q000379:methods*; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000737:chemistry* / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods*
D005290:Ferric Compounds; D012987:Soil; D012989:Soil Pollutants; D002119:Calcium Carbonate