Geophysical surveys (electromagnetic and GPR) of hydrocarbon contaminated soils at Scott Base, Marble Point, Bull Pass and Lake Vida

To determine how hydrocarbon contamination of Antarctic soils alters the geophysical response, and if so what was the nature of this response, was investigated at Scott Base with electromagnetic and ground penetrating radar surveys in areas where spills have occurred. The geophysical response was expected to be resistive due to the way that hydrocarbons interact with the salt and alter the electrical structure of the soil. How this response changes over the season was determined by sampling early (December) and later (February) in the same season. The surveys were run around the equipment store and extended up the road to the fuel storage tank. On the second trip, the survey also extended up the road on the other side of the store towards the main buildings. A 2m by 2m grid was used for the EM31 survey. At each point two readings were taken at orthogonal horizontal orientations to establish any anisotropic effect in the Scott Base soil. The GPR survey used lines at 2m spacings with readings taken every 20cm with the 200 MHz antennae. These same sites were repeated in the following year to examine year to year variations. The surveys were also extended to sites in the Dry Valleys (Bull Pass, Marble Point and Lake Vida) to obtain data from sites with different soils and climate.