A new soil remediation technology, using small electric currents to reduce fuel contamination, will be trialled at Australia’s Casey research station this summer*.
Powering pollution reduction
For more than a decade the Australian Antarctic Division’s risk and remediation teams have been developing and refining approaches to cleaning up fuel spills, and contaminated soil and water, in the unique conditions of Antarctica (Australian Antarctic Magazine 27: 1–3, 2014).
Senior Remediation Scientist, Mr Jeremy Richardson, said the new electric technology is a form of “electrokinetic remediation”.
“This involves inserting a number of electrodes into contaminated soil and pulsing a low voltage current through it, to break down hydrocarbon molecules and stimulate microbial activity,” he said.
Electrokinetic remediation will be used on soil that has already undergone several years of active remediation in ‘biopiles’, as well as soil that hasn’t undergone any processing.
“While this innovative technique has been used in warmer climates and the northern hemisphere, it has never been used in Antarctica, where the soil conditions are unique and microbes may react in different ways,” Mr Richardson said.
Remediation Project Manager, Mr Tim Spedding, said the biopiles work had shown indigenous Antarctic microbes can break down the hydrocarbons when the soil is carefully managed in the soil mounds.
“We have already been able to reduce contamination from 5000 parts per million to around 500 ppm, which is the first time bioremediation of bulk quantities of contaminated soil has been successful in Antarctica. Now we want to see if we can get those concentrations down even further,” Mr Spedding said.
The question of how low the residual fuel concentration in the soil can go is one the team is keen to explore, and the electrokinetics trial this summer is just one of several methods being trialled.
“Fuel is very complex; it has thousands of different compounds within it, each with different degrees of toxicity, and you need a diverse range of microorganisms and conditions to degrade those compounds at varying stages,” Mr Spedding said.
“We can’t clean everything entirely, but we want to clean it to a point where there is a very low risk to the environment or human health.
“To remove all contaminants you would effectively have to remove the soil in its entirety from Antarctica. But with less than one per cent of the continent ice-free, those areas are home to 99 per cent of Antarctic terrestrial biodiversity, so it’s important to keep the soil in place.”
The team is now drawing on decades of experience in cold climate remediation and eco-toxicology research to develop soil re-use guidelines for the Australian Antarctic Program.
“Currently there are no hard and fast target numbers for fuel contamination, as there are many different scenarios where you could reuse soil,” Mr Spedding said.
“You need to consider where it’s going to be re-used, in what manner, what potential impact that might have and what conditions you are trying to meet.
“For example, if the remediated soil is for unrestricted re-use on station, there needs to be much lower concentrations of residual fuel. But in certain situations, such as using it as back-fill for building foundations, the residual contaminant concentration can be higher, while still being a very low risk to the environment or human health.”
So far, around one quarter of the soil remediated at Casey station has been reused in building foundations.
Australian Antarctic Division
*Australian Antarctic Science Project 4036.
Clean-up manual has international impact
The work of Australian Antarctic Division remediation scientists guided the development of an Antarctic Clean-Up Manual, which was adopted by the Antarctic Treaty Consultative Meeting (ATCM) in 2013.
Chair of the ATCM’s Committee for Environmental Protection, Ewan McIvor, said Australia’s experience and expertise in cold climate remediation is well recognised by the Antarctic Treaty Parties.
“The national Antarctic programs are increasing their use of renewable energy sources, but the reality of Antarctic operations is that a lot of fuel is still used, and inevitably there are occasional spills or leaks into the environment,” Mr McIvor said.
“Countries are obliged to clean up their contaminated sites, and so the purpose of the manual is to present practical guidance on how best to do that, including approaches to site evaluation and containment, as well as techniques and technologies suitable for remediation in Antarctica.”
Other Antarctic Treaty parties such as Argentina, the United States and Brazil are also tackling similar issues, and the exchange of knowledge and personnel helps to enhance the success of individual and collective clean-up efforts.
“In 2014 we had a Brazilian scientist embedded with the team at Casey and this year two of our team have travelled to Brazil to share our learnings, as they formulate a plan to clean up the site where their station burned down in Antarctica five years ago,” remediation Project Manager, Mr Tim Spedding, said.
“We’re keen to share our experiences from decades of trial, error and triumphs, to help other Antarctic nations minimise the human impact on the extraordinary and fragile Antarctic environment.”