渗滤液污染羽中氧化还原带的动态发展演化研究

通过砂箱模拟实验研究了垃圾渗滤液污染羽中氧化还原带的动态发展和演化过程.结果表明,随着时间的推移和污染程度的加重,各氧化还原带不断向前推移,产甲烷带/硫酸盐还原带的范围不断扩大,随后出现惰性区.在氧化还原带的整个演化过程中,各带中TOC、硫化物、NH 4 -N、HC03-3、CO2和Fe2 等物质的浓度随时间的推移而升高,随离污染源距离的增加而降低;NO-3和DO等物质的浓度随时间的推移而减小,随离污染源距离的增加而升高;SO2-4的浓度则随时间的推移先减小而后增加,随离污染源距离的增加而降低.而且,随着污染程度的加重,沉积物中Fe3 含量降低, TOC含量升高.在氧还原带、硝酸盐还原带、铁还原带和产甲烷带/硫酸盐还原带沉积物中, Fe3 由占OXC的70.5%分别减小为56.3%、41%、28.3%和15%;TOC由占RDC的98.7%分别升高为102.0%、107.0%、142.9%和162.1%;Fe2 主要以PeS和FeCO3,沉淀形式沉积下来,分别占总Fe2 的80.6%、175.6%、377.7%和555.1%.

Dynamitic Development and Evolution of Redox Zones in Pollution Plume

A box filled with sandy soil was constructed to investigate dynamitic development and evolution of redox zones in landfill leachate-polluted plume. The results indicated that with time elapsing and pollution aggravating, redox zones moved ahead slowly; Methanogenic zone/ sulfate reduction zone extended gradually, and then inert zone appeared with further pollution. During the whole course of the dynamitic development and evolvement of redox zones, concentrations of TOC, sulfide, NH4(+) -N, HCO3-, CO2 and Fe2+ increased with time and decreased with distance; concentrations of NO3- and DO decreased with time and increased with distance; SO4(2-) concentration decreased first and then increased over time; but decreased with distance. Moreover, with time elapsing and pollution aggravating, the Fe3+ content of sediments was decrease and TOC was increase. Within oxygen reduction zone, nitrate reduction zone, iron reduction zone and methanogenic zone/sulfate reduction zone, Fe3+ content of sediments accounted for 70.5% of OXC decreased to 56.3%, 41%, 28.3% and 15%, and the TOC accounted for 98.7% of RDC increased to 102.0%, 107.0%, 142.9% and 162.1%, respectively; Fe2+ mainly precipitated as FeS and FeCO3, and accounted for 80.6%, 175.6%, 377.7% and 555.1% of total Fe2+, respectively.