US Army Engineer Research and Development Center, Environmental Laboratory, 3909 Halls Ferry Rd., Vicksburg, MS 39180, United States.
Chemosphere. 2010 Dec;81(11):1393-400. doi: 10.1016/j.chemosphere.2010.09.026. Epub 2010 Oct 12.
A storage pond dike failure occurred at the Tennessee Valley Authority Kingston Fossil Plant that resulted in the release of over 3.8 million cubic meters (5 million cubic yards) of fly ash. Approximately half of this material deposited in the main channel of the Emory River, 3.5 km upstream of the confluence of the Emory and Clinch Rivers, Tennessee, USA. Remediation efforts to date have focused on targeted removal of material from the channel through hydraulic dredging, as well as mechanical excavation in some areas. The agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could alter the redox state of metals present in the fly ash and thereby change their sorption and mobility properties. A series of extended elutriate tests were used to determine the concentration and speciation of metals released from fly ash. Results indicated that arsenic and selenium species released from the fly ash materials during elutriate preparation were redox stable over the course of 10d, with dissolved arsenic being present as arsenate, and dissolved selenium being present as selenite. Concentrations of certain metals, such as arsenic, selenium, vanadium, and barium, increased in the elutriate waters over the 10d study, whereas manganese concentrations decreased, likely due to oxidation and precipitation reactions.
田纳西河谷管理局金斯敦化石厂的一个储灰池堤坝发生故障，导致超过 380 万立方米（500 万立方码）的粉煤灰释放。这些物质大约有一半沉积在美国田纳西州埃默里河的主河道中，位于埃默里河和克林奇河的汇合处上游 3.5 公里处。迄今为止，补救工作的重点是通过水力疏浚有针对性地从河道中清除物质，以及在一些地区进行机械挖掘。在水力疏浚过程中，粉煤灰的搅动将河水引入粉煤灰中，这可能会改变粉煤灰中存在的金属的氧化还原状态，从而改变它们的吸附和迁移特性。进行了一系列扩展的淋滤试验，以确定从粉煤灰中释放的金属的浓度和形态。结果表明，在淋滤准备过程中，粉煤灰材料中释放的砷和硒形态在 10 天的过程中是氧化还原稳定的，溶解的砷以砷酸盐的形式存在，溶解的硒以亚硒酸盐的形式存在。某些金属的浓度，如砷、硒、钒和钡，在 10 天的研究中增加了淋滤水中，而锰的浓度下降，可能是由于氧化和沉淀反应。
