垃圾渗滤液水溶性有机物对土壤Pb溶出的影响

研究了不同填埋年限（0 a、4～5 a、12 a）的垃圾渗滤液水溶性有机物（DOM）对2种污染土壤重金属Pb溶出的影响.结果表明,垃圾渗滤液DOM具有促进土壤Pb溶出的作用.填埋年限不同的垃圾渗滤液DOM对土壤Pb溶出的影响不同,填埋年限短的垃圾渗滤液DOM对土壤Pb溶出率最高.因为填埋年限越长,垃圾渗滤液DOM中高分子组分（相对分子质量>25?000）所占比例越高,而高分子组分相对于低分子组分（相对分子质量<1?000）对土壤Pb溶出能力较弱.红壤中,渗滤液DOM的低分子组分对Pb的平均溶出率高出高分子组分123.8%;潮土中也表现出类似的结果.与无渗滤液DOM的对照相比,垃圾渗滤液DOM的加入明显提高污染土壤Pb的平均溶出率,并且随体系pH的升高,DOM这种促进作用表现得更为明显.

Effect of Dissolved Organic Matter from Landfill-Leachates on Dissolution of Pb in Soils

Dissolution of lead in two contaminated soils facilitated by dissolved organic matter(DOM) from the different ages of landfill leachate (0 a, 4 - 5 a, 12 a) were studied with a batch desorption trial. The results show that landfill leachate DOM obviously facilitated dissolution of Pb in the contaminated soils. Moreover, the shorter landfill ages, the higher dissolution rate. It was found that the content of the higher molecular weight fraction of landfill leachate DOM was increased with the increase of landfill ages. Generally, lower molecular weight fraction (M(r) < 1 000) would lead to soil Pb mobilization easier than the higher molecular weight fraction (M(r) > 25 000) . For example, the average net dissolution rates of Pb in a contaminated acidic red soil were enhanced by 123.8% in the presence of lower molecular weight fraction of DOM, with comparison to than that in the presence of a higher molecular weight fraction. Similar results were also observed in the contaminated calcareous soil. The average dissolution rates of Pb in the contaminated soils amended with landfill leachate was increased with pH increase in comparison with in the absence of landfill-leachate.