Abstract

This paper reports the results of a seven-year study of a phytoremediation system consisting of 349 hybrid poplars (Populous deltoids x Populus nigra ‘DN-21’) that were emplaced to reduce the migration of impacted groundwater toward a nearby stream. For the relatively small tree stand, the achievement of hydraulic containment was challenged by several factors, including topographic constraints on tree placement, spatial heterogeneity in depth-to-groundwater, and lack of controls on surface runoff. However, the interpretation of measured diurnal water table fluctuations indicated substantial and increasing levels of groundwater extraction, consistent with poplar sap flow measurements collected during two growing seasons. The project also provided unique educational experiences for undergraduate and graduate students from multiple academic disciplines who participated in monitoring, site maintenance, and data interpretation.

Novelty statement The paper adds to the limited literature on poplar-based phytoextraction of contaminated groundwater by describing a seven-year case study with detailed hydrologic measurements. Novel elements include (1) a very large data set of poplar sap flow measurements that provides insight into potential spatial and temporal variability, and (2) a detailed application of an under-utilized analytical tool (water table fluctuations) to evaluate hydraulic capture.

摘要

本文报告了一项为期七年的植物修复系统研究结果，该系统由 349 棵杂交杨树 ( Populous deltoids x Populus nigra'DN-21'）被安置以减少受影响的地下水向附近溪流的迁移。对于相对较小的林分，水力遏制的实现受到几个因素的挑战，包括树木放置的地形限制、深度到地下水的空间异质性以及缺乏对地表径流的控制。然而，对测量的昼夜地下水位波动的解释表明，地下水抽取量显着且不断增加，这与在两个生长季节收集的杨树液流测量结果一致。该项目还为参与监测、现场维护和数据解释的多个学科的本科生和研究生提供了独特的教育体验。

新颖性声明本文通过描述一项为期七年的详细水文测量案例研究，增加了关于基于杨树植物提取受污染地下水的有限文献。新元素包括（1）一个非常大的杨树液流测量数据集，可以深入了解潜在的空间和时间变化，以及（2）详细应用未充分利用的分析工具（地下水位波动）来评估水力捕获。