Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals

• Published in: Environmental science and pollution research international Vol. 21; no. 15; pp. 8964 - 8980
• Main Authors: Wehrer, Markus, Lissner, Heidi, Bloem, Esther, French, Helen, Totsche, Kai Uwe
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 2014; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Aeration zone; Airports; Antifreeze solutions; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Chemicals; Conductivity; Contaminants; Contamination; Deicers; Earth and Environmental Science; Ecotoxicology; Electric Conductivity; electrical resistance; Electrical resistivity; Environment; Environmental Chemistry; Environmental Health; Environmental monitoring; Environmental Monitoring - methods; Groundwater; hydrogen; Infiltration; lysimeters; melting; Meltwater; Moisture content; monitoring; Monitoring and Modelling; New Approaches for Low-Invasive Contaminated Site Characterization; potassium; Salinity; seepage; Snowmelt; Soil - chemistry; Soil contaminants; Soil contamination; Soil degradation; Soil pollution; Soil water; spring; Studies; Tomography; Waste Water Technology; Water; Water content; Water Management; Water Movements; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Pollution Control; Water seepage; Weather; Europe; Degradation; Propylene glycol; Electrical resistivity; Non-invasive monitoring; Unsaturated; Mobile immobile; Ground truth; Preferential flow; Degradable tracer; Vadose; Heterogeneous transport
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-013-2252-2

Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques.