Gonsoulin Mary E, Wilson Barbara H, Wilson John T
US Environmental Protection Agency, Robert Kerr Research Laboratory, OK 74820, USA.
Biodegradation. 2004 Dec;15(6):475-85. doi: 10.1023/b:biod.0000044588.86054.05.
The Refuse Hideaway Landfill (23-acre) received municipal, commercial, and industrial waste between 1974 and 1988. It was designed as a "natural attenuation" landfill and no provision was made to collect and treat contaminated water. Natural biological degradation through sequential reductive dechlorination had been an important mechanism for natural attenuation at the site. We used the concentration of hydrogen to forecast whether reductive dechlorination would continue over time at particular locations in the plume. Based on published literature, reductive dechlorination and natural attenuation of PCE, TCE, and cis-DCE can be expected in the aquifer if the concentration of molecular hydrogen in monitoring wells are adequate (> 1 nanomolar). Reductive dechlorination can be expected to continue as the ground water moves down gradient. Natural attenuation through reductive dechlorination is not expected in flow paths that originate at down gradient monitoring wells with low concentrations of molecular hydrogen (< 1 nanomolar). In three monitoring wells at the margin of the landfill and in five monitoring wells down gradient of the landfill, ground water maintained a molecular hydrogen concentration, ranging from 1.30 to 9.17 nanomolar, that is adequate for reductive dechlorination. In three of the monitoring wells far down gradient of the landfill, the concentration of molecular hydrogen (0.33 to 0.83 nanomolar) was not adequate to support reductive dechlorination. In wells with adequate concentrations of hydrogen, the concentrations of chlorinated volatile organic compounds were attenuated over time, or concentrations of chlorinated volatile organics were below the detection limit. In wells with inadequate concentrations of hydrogen, the concentrations of chlorinated organic compounds attenuated at a slower rate over time. In wells with adequate hydrogen the first order rate of attenuation of PCE, TCE, cis-DCE and total chlorinated volatile organic compounds varies from 0.38 to 0.18 per year. In wells without adequate hydrogen the rate varies from 0.015 to 0.006 per year.
垃圾隐匿填埋场（占地23英亩）在1974年至1988年期间接收城市、商业和工业垃圾。它被设计为一个“自然衰减”填埋场，未设置收集和处理受污染水的设施。通过顺序还原脱氯进行的自然生物降解一直是该场地自然衰减的重要机制。我们利用氢气浓度来预测羽流中特定位置的还原脱氯是否会随时间持续。根据已发表的文献，如果监测井中的分子氢浓度足够（>1纳摩尔），则预计含水层中会发生PCE、TCE和顺式DCE的还原脱氯及自然衰减。随着地下水向下游流动，预计还原脱氯会持续。在源自分子氢浓度低（<1纳摩尔）的下游监测井的水流路径中，预计不会通过还原脱氯实现自然衰减。在填埋场边缘的三口监测井以及填埋场下游的五口监测井中，地下水的分子氢浓度维持在1.30至9.17纳摩尔之间，足以进行还原脱氯。在填埋场下游远处的三口监测井中，分子氢浓度（0.33至0.83纳摩尔）不足以支持还原脱氯。在氢气浓度足够的井中，随着时间推移，氯化挥发性有机化合物的浓度会降低，或者氯化挥发性有机化合物的浓度低于检测限。在氢气浓度不足的井中，随着时间推移，氯化有机化合物的浓度降低速度较慢。在氢气浓度足够的井中，PCE、TCE、顺式DCE和总氯化挥发性有机化合物的一级衰减速率每年在0.38至0.18之间变化。在氢气浓度不足的井中，该速率每年在0.015至0.006之间变化。
