A new approach to investigating petroleum-contaminated sites has been explored by US researchers. Todd Halihan and colleagues at Oklahoma State University and the University of Nevada have used electrical resistivity imaging (ERI) to track pollutants.

Although this technique has been used for geological mapping, this is the first example of its use in a remediated site to give quantitative information about pollution. ERI is particularly useful for mapping liquids, such as gasoline, which are lighter than water.

Findings from these investigations show that methods used in the past, for example discrete point sampling of liquids or indirect measurement through borehole or drilling techniques, did not provide accurate pictures of contamination in an entire area.

Conversely, ERI allows researchers to look at a complete region. It could provide a cheaper and better long term solution for monitoring sites contaminated with gasoline or other non-aqueous liquid pollutants.

Niamh O'Connor