Effects of pre-exposure on the indigenous biodegradation of 14C-phenanthrene in Antarctic soils

- PAHs are present in Antarctic soils despite the absence of point sources.
- PAH degraders are present in these 'pristine' soils.
- Temperature plays an important role in the extent of biodegradation.
- Pre-exposure is also important in biodegradation of PAHs in soil.

The aim of this study was to investigate the biodegradation of phenanthrene in five Antarctic soils over 150 days at various temperatures and under slurry conditions. The development of catabolic activity was measured over time (1, 30, 60, 150 days) by the addition of 14C-phenanthrene and measuring changes in the lag phases, rates and extents of 14C-phenanthrene degradation. As the temperature increased (4 °C, 12 °C, 22 °C, 22 °C slurry), the highest extents of 14C-phenanthrene mineralisation increased significantly (0.46%, 12.21%, 24.82%, 60.81%), respectively. This was due to changes in the water availability and 14C-phenanthrene dissolution in aqueous phase, thus enhancing bioaccessibility of the contaminant to indigenous microorganisms within the soil. High catabolic activities can develop in Antarctic soils where appropriate conditions are ensured. However, further studies are however needed to explore the changes in microbial community structure that occur at different incubation temperatures.