Environmental geophysics at Scott Base: ground penetrating radar and electromagnetic induction as tools for mapping contaminated ground at Antarctic research bases

Abstract

Mapping the extent of hydrocarbon spills in Antarctica is commonly done by hand sampling of active layer soils and by mechanical coring deeper into the frozen layer. While these methods provide reliable results, the act of obtaining samples can cause almost as much damage to the site as the contamination. A nondestructive, noninvasive method to map extent of hydrocarbon (JP5, JP8) spills on dry permafrost would provide a more environmentally sound contaminated site management tool. This study provides a base knowledge of how noninvasive nondestructive geophysical surveying can be used to map hydrocarbon spills in an Antarctic permafrost setting, and establishes its suitability as a tool for environmental monitoring at Antarctic bases. Geophysical surveys were undertaken at Scott Base, Antarctica, using ground penetrating radar (GPR) and the EM31™ horizontal loop electromagnetic (HLEM) instrument. Surveys were carried out over the same location before and after the summer melt. Areas known to be hydrocarbon-contaminated appeared as resistive anomalies using an EM31. Variations in the geophysical response between surveys were found, with conductivities increasing, on average, by a factor of two for the late summer, but resistive anomalies persisted. GPR was not successful in direct detection of contaminated ground; however, it did provide valuable information on the nature of the subsurface which is useful to predict future movement of contaminants.