Cleaning up an unforgiving landscape

We have certain images in our minds about what Antarctica is like: vast expanses of clean, un-trodden ice and snow, scattered huts, penguins, and an unforgiving weather forecast. However, when Meenakshi Arora from the Department of Infrastructure Engineering at the University of Melbourne first arrived in Antarctica in 2008, it was to be part of a project to clean-up a mess.

“It is not quite as you imagine. There are unique problems present in Antarctica relating to pollution and environmental damage. New clean-up solutions are needed, as the harsh environment makes it very challenging for existing practices to work successfully there,” Dr Arora says.

Australia has three research stations on the Australian Antarctic Division (Casey, Mawson and Davis) and fuel is essential to making life possible in such a cold and harsh environment. But with fuel comes risk; spillage, environmental contamination and potential damage to the landscape.

In Winter 1999, an accidental spillage occurred at Casey station that had the potential to tarnish and seriously damage the landscape. It was not clear how many litres of fuel had spilled nor was it known how to redress such a situation. Over the summer, a spill assessment was conducted, that went from the spill point to the coastline to assess the extent of contamination and flow of contaminated melt water.

The group also realised that not all of Antarctica is pristine. Rubbish has been dumped in the past in the form of a tip site and as the snow melts in the warmer months, the rubbish spreads, taking dangerous contaminants with it. Batteries containing lead, a necessity in Antarctica, were part of that rubbish mix. At first, the contamination was thought to have been confined to a small area, but it was soon established that exposure was more widespread. The Australian Antarctic Division has had a program in place to remediate the contaminated tip site, with small amounts of soil from the contaminated area extracted and sent to Hobart for testing and treatment.

Back at the University of Melbourne, Professor Stevens and his colleagues - in collaboration with researchers from the Australian Antarctic Division and Macquarie University - worked on a plan to change the contaminants into a more stable and less harmful form. By examining various chemical materials, the University of Melbourne team worked on ways for contaminants to be absorbed into the landscape but be potentially less harmful. With the assistance of an ARC grant, the team commenced a trial on a range of materials, previously simulated in freezing conditions in 2006, by installing a Permeable Reactive Barrier (PRB) downstream of an oil spill site at Casey. A testing cage reaching more than a metre deep was constructed and planted into the frozen earth. The team looked for ways to increase the life of the barrier by enhancing the microbes that eat oil.

Dr Arora performed detailed laboratory analysis and modeling to help design such plants with greater accuracy. Taking the best possible solutions with her, she returned to Antarctica in January 2010 and spent the summer testing the performance of PRB along with team-members Kathryn Mumford and Tim Spedding.

Different chemicals work in particular ways at certain temperatures but being in Antarctica meant a whole new way of operating. Faced with the freezing temperatures and thaw cycles, it was a challenge to come up with new solutions to chemical problems. The main idea behind the testing cage was to look at the performance of different materials and the effects of microbes on pollutant levels, so future spills could be contained with more ease.

While the project is almost in the completion stage, Dr Arora and the project team are keeping an eye on progress from a distance.

“A clean Antarctica matters to all of us and engineers have a role to play in making certain that this unique landscape is protected and preserved,” she says.

http://www.eng.unimelb.edu.au