Date of Award

8-1997

Degree Name

Master of Science

Department

Geological and Environmental Sciences

Department

Geosciences

First Advisor

Dr. Estella Atekwana

Second Advisor

Dr. William Sauck

Third Advisor

Dr. Michael Barcelona

Access Setting

Masters Thesis-Open Access

Abstract

The detection of hydrocarbon contamination in the subsurface using geophysical techniques has been based on the known physical properties of high electrical resistivities (ρa) (low conductivities). However, geophysical field investigations at uncontrolled spill sites yield measurements of low resistivity (high conductivity). The purpose of this study is to test that in the natural environment some hydrocarbon spills (in the case of LNAPLs), can exhibit changes with time due to biodegradation, from electrically resistive to conductive. Since time is an important factor, this hypothesis was tested at a site where the time when a hydrocarbon release occurred is known and where active biodegradation has taken place.

The results of this study support the proposed hypothesis. The geophysical high conductivity anomalies, detected by electromagnetic, electrical resistivity and self potential methods, were often complemented by the hydrochemistry data of high conductive groundwater (>200μS/cm). Hydrogeochemical results show evidence that this site is in advanced stages of biodegradation. Researchers in future studies need to carefully assess a site's stage of biodegradation, quantity of hydrocarbon contamination, and the geology of the site, before conducting a field survey, since these conditions appear to be the dominating factors in the detection of the byproducts from the biodegradation of hydrocarbon contamination.

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