Zhang Yi, Khan Imtiyaz A, Chen Xun-Hong, Spalding Roy F
Department of Agronomy and Horticulture, Keim Hall, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
J Contam Hydrol. 2006 Jan 10;82(3-4):183-94. doi: 10.1016/j.jconhyd.2005.09.007. Epub 2005 Dec 5.
Ethanol is rapidly replacing methyl tert-butyl ether (MtBE), the primary fuel oxygenate in the US, and ethanol releases from spills and leaky underground storage tanks (LUSTs) are anticipated. Ethanol has received little attention as a potential groundwater contaminant. This study investigates the fate and transport of ethanol under transient conditions in a sand and gravel aquifer. A pulse containing approximately 220 mg L-1 ethanol and 16 mg L-1 bromide was injected into the shallow sand and gravel aquifer and monitored to estimate its persistence and transport. The plume was monitored for 2.5 months using downgradient multilevel samplers (MLSs). Values for ethanol retardation were measured from ethanol and bromide breakthrough data and compared to estimates using published Koc values for low carbon aquifer sediments (foc=10 microg C g-1 sediment). Ethanol transport was not retarded (R=0.99). A 3-dimensional model reasonably simulated bromide and ethanol breakthrough curves. An average first-order decay constant was estimated to be 0.32 d-1 (t1/2=2.2 d). At the second fence, 75% of the injected bromide and less than 3% of ethanol remained in the plume. Monitored terminal electron acceptor concentrations demonstrated that the majority of the ethanol was transformed by anaerobic processes other than denitrification and sulfate reduction.
乙醇正在迅速取代美国主要的燃料含氧化合物甲基叔丁基醚（MtBE），预计会出现因乙醇泄漏和地下储油罐（LUSTs）渗漏而导致的乙醇释放情况。乙醇作为一种潜在的地下水污染物，很少受到关注。本研究调查了在瞬态条件下乙醇在砂卵石含水层中的归宿和运移情况。将含有约220毫克/升乙醇和16毫克/升溴化物的脉冲注入浅层砂卵石含水层，并进行监测以估算其持久性和运移情况。使用下游多级采样器（MLS）对羽流进行了2.5个月的监测。根据乙醇和溴化物的穿透数据测量乙醇阻滞值，并与使用已发表的低碳含水层沉积物Koc值（foc = 10微克碳/克沉积物）的估算值进行比较。乙醇运移未受到阻滞（R = 0.99）。一个三维模型合理地模拟了溴化物和乙醇的穿透曲线。估计平均一级衰减常数为0.32天-1（t1/2 = 2.2天）。在第二个围栏处，注入的溴化物中有75%，而乙醇中不到3%仍留在羽流中。监测到的终端电子受体浓度表明，大部分乙醇是通过反硝化和硫酸盐还原以外的厌氧过程转化的。
