ABSTRACT To improve risk assessment, control and treatment strategies of contaminated sites, we require accurate methods for monitoring solute transport and infiltration in the unsaturated zone. Highly spatio‐temporal heterogeneous infiltration during snowmelt increases the risk of contaminating the groundwater in areas where de‐icing chemicals are required for winter maintenance of roads and runways. The objective of this study is to quantify how the different processes occurring during snowmelt infiltration of contaminated meltwater affect bulk electrical resistivity. Field experiments conducted at Moreppen experimental lysimeter trench are combined with heterogeneous unsaturated soil modelling. The experimental site is located next to Oslo airport, Gardermoen, Norway, where large amounts of de‐icing chemicals are used to remove snow and ice every winter. Bromide, an inactive tracer, and the de‐icing chemical propylene glycol were applied to the snow cover prior to the onset of snowmelt, and their percolation through the unsaturated zone was monitored with water sampling from 37 suction cups. At the same time, cross‐borehole time‐lapse electrical resistivity measurements were recorded along with measurements of soil water tension and temperature. Images of two‐dimensional (2D) bulk resistivity profiles were determined and were temperature corrected, to compensate for the change in soil temperature throughout the melting period. By using fitted parameters of petrophysical relations for the Moreppen soil, the tensiometer data gave insight into the contribution of water saturation on the changes in bulk resistivity, while water samples provided the contribution to the bulk resistivity from salt concentrations. The experimental data were compared with numerical simulation of the same experimental conditions in a heterogeneous unsaturated soil and used to quantify the uncertainty caused by the non‐consistent resolutions of the different methods, and to increase our understanding of the resistivity signal measured with time‐lapse electrical resistivity tomography. The work clearly illustrates the importance of ground truthing in multiple locations to obtain an accurate description of the contaminant transport.

中文翻译：

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了解在受污染的融雪渗透过程中用延时电阻率测量的电阻率信号

摘要 为了改进污染场地的风险评估、控制和处理策略，我们需要准确的方法来监测非饱和带中溶质的迁移和渗透。融雪过程中高度的时空异质渗透增加了在冬季维护道路和跑道需要除冰化学品的地区污染地下水的风险。本研究的目的是量化融雪渗入受污染融水期间发生的不同过程如何影响体电阻率。在 Moreppen 实验性蒸渗仪沟槽进行的现场实验与非均质非饱和土壤建模相结合。实验地点位于挪威加勒穆恩奥斯陆机场旁，每年冬天都会使用大量除冰化学品来清除冰雪。在融雪开始之前，将溴化物、一种非活性示踪剂和除冰化学丙二醇应用于雪盖，并通过 37 个吸盘的水样监测它们通过不饱和区的渗透。同时，记录了跨钻孔延时电阻率测量值以及土壤水分张力和温度的测量值。二维 (2D) 体电阻率剖面图像被确定并进行温度校正，以补偿整个融化期间土壤温度的变化。通过使用 Moreppen 土壤岩石物理关系的拟合参数，张力计数据揭示了水饱和度对体电阻率变化的贡献，而水样提供了盐浓度对体电阻率的贡献。将实验数据与非均质非饱和土壤中相同实验条件的数值模拟进行比较，并用于量化由不同方法的不一致分辨率引起的不确定性，并增加我们对延时测量电阻率信号的理解电阻率断层扫描。这项工作清楚地说明了在多个地点进行地面实况调查以获得准确描述污染物迁移的重要性。将实验数据与非均质非饱和土壤中相同实验条件的数值模拟进行比较，并用于量化由不同方法的不一致分辨率引起的不确定性，并增加我们对延时测量电阻率信号的理解电阻率断层扫描。这项工作清楚地说明了在多个地点进行地面实况调查以获得准确描述污染物迁移的重要性。将实验数据与非均质非饱和土壤中相同实验条件的数值模拟进行比较，并用于量化由不同方法的不一致分辨率引起的不确定性，并增加我们对延时测量电阻率信号的理解电阻率断层扫描。这项工作清楚地说明了在多个地点进行地面实况调查以获得准确描述污染物迁移的重要性。