Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
Waste Manag. 2017 Sep;67:203-213. doi: 10.1016/j.wasman.2017.05.012. Epub 2017 May 12.
Leachates from solid-waste landfills are considered a severe threat to groundwater quality. The fate of pollutants in the waste and underlying unsaturated zone is crucial for evaluating environmental risks and selecting a restoration strategy. In this study, a vadose-zone monitoring system (VMS) installed in a municipal landfill was used, for the first time, to continuously track leachates percolation dynamics and assess their chemical transformation across the entire thickness of the waste body (15m) and underlying unsaturated zone (16m) to the water table. Winter rains were found to quickly infiltrate through the waste and underlying vadose zone despite a clay cover that was implemented as part of a restoration and leachate-prevention strategy. Within the waste body, the flow pattern was controlled by preferential flow paths, which changed frequently. It is hypothesized that ongoing decomposition of the waste creates dynamic variations in the waste's physical structure and flow pattern. Water samples collected from the waste layer indicated the formation of highly polluted leachates. The chemical composition in the waste body showed extreme variability between sampling points with respect to DOC (407-31,464mg/L), BOD/COD ratios (0.07-0.55), Fe (6.8-1154mg/L), ammonium (68-2924mg/L) and heavy metal concentrations. Environmental hot spots creating concentrated, aggressive, "acid-phase" leachates still exist in the waste more than 13years after closing the landfill. However, continuous changes in the flow pattern and moisture distribution affected the creation and decay of such environments. In the underlying sandy vadose zone, some sections repeatedly exhibited stronger and faster flow characteristics than others. These local fluxes of concentrated leachates rapidly transported heavy contaminant loads toward the groundwater. However results showed evidence of continual attenuation processes in the deep vadose zone, with the anaerobic digestion of organic matter, as well as the significant retention of heavy metals.
垃圾填埋场的渗滤液被认为是地下水水质的严重威胁。评估环境风险和选择修复策略时，废物和下面非饱和带中污染物的命运至关重要。本研究首次使用安装在城市垃圾填埋场的包气带监测系统（VMS）连续跟踪渗滤液渗流动态，并评估其在整个垃圾体（15m）和下面非饱和带（16m）直至地下水位的化学转化。尽管实施了粘土覆盖作为修复和渗滤液预防策略的一部分，但冬季降雨仍迅速渗透通过废物和下面的包气带。在废物体中，流动模式受优先流路径控制，这些路径经常变化。据推测，废物的持续分解会导致废物物理结构和流动模式的动态变化。从废物层采集的水样表明形成了高度污染的渗滤液。废物体中化学组成在采样点之间表现出极高的可变性，DOC（407-31,464mg/L）、BOD/COD 比（0.07-0.55）、Fe（6.8-1154mg/L）、铵（68-2924mg/L）和重金属浓度。在关闭垃圾填埋场 13 年多后，仍有环境热点在垃圾中形成集中、腐蚀性的“酸性相”渗滤液。然而，不断变化的流动模式和水分分布影响了这些环境的形成和衰减。在下面的沙质包气带中，一些地段的流动特征比其他地段更强、更快。这些集中渗滤液的局部通量迅速将重污染物负荷输送到地下水。然而，结果表明，在深部包气带中存在持续的衰减过程，包括有机物的厌氧消化以及重金属的大量截留。
