Effect of Dissolved Organic Matter in Simple Landfill Leachate on the Dissolution and Migration of Pb(II)

A simple municipal solid waste landfill can generate large amounts of leachate. Dissolved organic matter( DOM) from this leachate would increases the transport of heavy metals such as Pb( Ⅱ) after leaching into the soil. This study aims to assess,with the aid of fluorescence quenching analysis,the binding ability of DOM from landfill leachate with different ages( 5 a and 10 a) toward to Pb( Ⅱ) as well as the migration ability of DOM to Pb( Ⅱ) using a soil column leaching experiment. The fluorescence quenching analysis showed that the percentage of fluorophores with UV and visible fulvic acid-like regionin 10 a landfill leachate DOM increased by 17. 68%,and 7. 96% compared with that of the 5 a. Simultaneously,the conditional stability constants( lg K) of UV and visible fulvic acid-like matter of DOM in the 10 a decreased by 10. 13%,and 17. 42% respectively over the 5 a. The soil column leaching experiment indicated that the total migration of Pb(Ⅱ) in soil leached by DOM derived from the 5,and 10 a landfill leachate was 2. 41,and 1. 98 times greater respectively compared with that of the control. The result suggestes that the landfill leachate DOM could greatly promote Pb(Ⅱ) migration in soil. In addition,the migration potential( 36. 09) and migration rate( 0. 17) of Pb(Ⅱ) leached by the 10 a landfill leachate DOM was lower than that of 5 a( 43. 71,0. 19) which revealed that the migration ability of DOM to Pb(Ⅱ) in soil decreased with the extension of landfill age. Furthermore,the 6 h mobility of Pb( Ⅱ) increased from 3. 375% to 3. 750% while that daring 6-12 h increased from 0. 875% to 2. 000%,when the concentration of DOM in the eluting solution increased from 32. 5 mgL to 130. 0 mgL. The analysis results showed that the migration ability of DOM to Pb( Ⅱ) wasaffected by the concentration,landfill ages,and leaching time of landfill leachate DOM.