Rubbish removal and site remediation
Photo: Paul Goldsworthy
The Antarctic has many features that make the clean-up of contaminated sites particularly difficult. We know little about the behaviour of contaminants under Antarctic conditions, although there has been some progress in research in this area in recent years. We are also looking to case studies in the Arctic to learn from this experience.
The seasonal cycle of freezing and thawing means that for much of the year the soils are virtually impenetrable to all but the most powerful excavation techniques. But during the summer when the snow melts and digging would be easy, water flows through the refuse tip sites and into the sea. Thoughtless excavation at this time would stir-up and mobilize the contaminants and disperse them widely into the marine environment.
Contaminants from waste disposal sites have leached into the soils and the amount of contaminated material to be handled is now much more than the volume of material originally brought to Antarctica. The relatively small cargo capacity of ships, the enormous volumes of contaminated material and the very great distances across the Southern Ocean, mean that shipment back to the place of origin would take many years. In practice, it may not be feasible to ship out all the waste material, and in situ remediation may be the only realistic option. However, this will also be difficult under Antarctic conditions, as the low temperatures, the lack of available water and the very low levels of nutrients will slow biological remediation.
To address these problems we are considering excavation techniques that work in frozen ground and will be testing rippers and operating procedures. Even if we can excavate while the ground is still frozen there will be a time during the summer melt when water flows through the recently exposed soils. We have installed small-scale experiments to test whether filters and reactive barriers such as activated charcoal can be used to filter the water flow and limit contaminant dispersion. We have also established experiments to determine how conditions can be optimised for in situ remediation of soils contaminated with hydrocarbons such as spilt fuel and oil.
In 2008 a synthesis of existing knowledge of the bioremediation of petroleum hydrocarbon contaminated sites in cold regions, including the Arctic and Antarctic, was completed, resulting in publication of the book 'Bioremediation of Petroleum Hydrocarbons in Cold Regions'.