Summary
An increase in high latitude human activities has resulted in an increased incidence of petroleum hydrocarbon spills in these areas. While a substantial body of research exists on remediation techniques for such contamination in warmer climes, these methods are often inappropriate nearer the poles because microbial processes are limited by cold temperatures, and ex situ processing is costly and impracticable. Furthermore, little information on the sensitivity of invertebrate and microbial biota to contamination exists, and remediation targets to maximise soil ecosystem health remain poorly defined for these regions. In recent decades, subantarctic Macquarie Island (54°30’ S, 158°57’ E) has experienced a number of spills of varying magnitude, mostly of Special Antarctic Blend (SAB) diesel fuel. While some research exists on the biological effects of fresh fuel spills, the work presented here describes initial investigations regarding responses to aged fuel and residual fuel products remaining in the soil over time. Single species 14-day acute toxicity tests were carried out using the endemic earthworm, Microscolex macquariensis in soils collected from 11 sites near the research station. Mortality rates were not significantly different between control soil collected from a pristine area and soils with various histories of contamination over this period. It is anticipated that longer-term, chronic toxicity tests may better detect any toxicity effects, and indeed represent a more meaningful result for what are chronically contaminated soils; this will be pursued in future studies. Cores of the same soils were also collected to investigate changes in the composition and concentration of SAB as it ages, and how invertebrate and microbial communities have responded to residual SAB contamination. Results from this work will inform decision making processes regarding fuel spill remediation in the region generally, as well as the definition of remediation targets for when spills no longer pose a significant environmental risk.
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