ELECTRICAL RESITIVITY IMAGING DURING A DILUTION TRACER TEST TO MODEL HYPORHEIC FLOW OF ACID MINE DRAINAGE

Open Access
- Author:
- Herwehe, Lauren Marie
- Area of Honors:
- Geosciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Kamini Singha, Thesis Supervisor
Dr. Kamini Singha, Thesis Supervisor
Dr. Peter J Heaney, Thesis Honors Advisor - Keywords:
- acid mine drainage
hyporheic zone
electrical resistivity imaging
electrical conductivity
hydrodynamics
hydrogeology - Abstract:
- Tracer tests have long been a method of obtaining information on contaminant transport and the advective and dispersive processes acting in streams. Dilution tracer tests are uncommon but can prove highly useful in analyzing severely contaminated water in which a standard ionic tracer would not be sufficient, such as with acid mine drainage (AMD). The use of resistivity measurements to create cross-sectional images of the hyporheic zone is a relatively new method. In this study, we pair the use of a dilution tracer test with electrical resistivity imaging (ERI) to assess the spatial extent and flow behavior of AMD. To our knowledge, this is the first study to pair these methods to the assessment of AMD. The ERI profiles indicate that the AMD had little impact past the farthest downstream transect. The ERI profiles also show the preferential flow paths of the AMD water. Regions of faster flow indicate increased mixing of aerobic and anaerobic sediment. This leads to an increased rate of oxidation of aqueous Fe2+ to Fe3+ precipitate, which is important for remediation and the removal of Fe2+ ions. Hydrodynamics and aerobic/anaerobic mixing also affect microbial life. The mean apparent resistivity values collected at each transect showed that the impact of AMD flow on the hyporheic zone was highly dependent upon distance from the AMD source. The well electrical conductivity data are consistent with the ERI, in showing that distance from the tracer source was the most important variable in predicting the impact that it would have.