简易填埋场垃圾渗滤液水溶性有机物对Pb(Ⅱ)迁移转化特性的影响

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

  • 摘要: 为研究简易填埋场垃圾渗滤液DOM(dissolved organic matter, 水溶性有机物)对重金属Pb(Ⅱ)的配位与迁移溶出的影响,运用荧光猝灭分析及柱模拟技术,研究了不同填埋年限(5和10a)简易填埋场垃圾渗滤液DOM与Pb(Ⅱ)的相互作用. 三维荧光猝灭分析表明,填埋10a的垃圾渗滤液DOM紫外区、可见区类富里酸配位荧光基团所占的比例分别比填埋5a的垃圾渗滤液增加了17.68%和7.96%;而配位稳定常数(lg K)则分别降低了10.13%和17.42%. 柱模拟试验结果表明,垃圾渗滤液DOM对土壤中Pb(Ⅱ)的纵向迁移具有促进作用,填埋5和10a的垃圾渗滤液DOM对Pb(Ⅱ)的累计迁移率分别是对照组的2.41和1.98倍. 与填埋5a相比,填埋10a的垃圾渗滤液DOM对Pb(Ⅱ)的溶出能力显著降低,表明随着填埋年限的增加,渗滤液DOM对Pb(Ⅱ)的溶出能力呈降低趋势. 对相同填埋年限的垃圾渗滤液,ρ(DOM)越高,对Pb(Ⅱ)的迁移溶出能力越强;Pb(Ⅱ)的平均迁移量会随着填埋时间的推移逐步降低.

     

    Abstract: 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 (5a and 10a) 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 10a landfill leachate DOM increased by 17.68%, and 7.96% compared with that of the 5a. Simultaneously, the conditional stability constants(lg K)of UV and visible fulvic acid-like matter of DOM in the 10a decreased by 10.13%, and 17.42% respectively over the 5a. The soil column leaching experiment indicated that the total migration of Pb(Ⅱ) in soil leached by DOM derived from the 5, and 10a landfill leachate was 2.41, and 1.98times 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 10a landfill leachate DOM was lower than that of 5a (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 6h mobility of Pb(Ⅱ) increased from 3.375% to 3.750% while that daring 6-12h increased from 0.875% to 2.000%, when the concentration of DOM in the eluting solution increased from 32.5mg/L to 130.0mg/L. The analysis results showed that the migration ability of DOM to Pb(Ⅱ) was affected by the concentration, landfill ages, and leaching time of landfill leachate DOM.

     

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