The effects of nitrogen and water on mineralisation of hydrocarbons in diesel-contaminated terrestrial Antarctic

Bioremediation of petroleum-contaminated soil in the Antarctic will be logistically and technically difficult and will cost more than similar treatment in temperate regions or the Arctic because of the remote location and unfavourable environmental conditions. To optimise nutrient amendments for the remediation of a long-term hydrocarbon-contaminated site at Old Casey Station in Antarctica, we investigated the effects of nitrogen (and phosphorus) amendments on microbial mineralisation using radiometric microcosm experiments and gas chromatography. Hydrocarbon mineralisation at nine different inorganic nitrogen concentrations (ranging from 85 to over 27,000 mg N kg-soil-H2O-1) was monitored over 95-day incubation at 10degreesC. Total C-14-octadecane mineralisation increased with increasing nutrient concentration peaking in the range 1000-1600 mg N kg-soil-H2O-1. The microcosms with the lowest and highest concentrations of N had extended lag phases of over 12.5 days prior to significant mineralisation. Gas chromatographic analysis of the aliphatic components of Special Antarctic Blend (SAB) diesel in the contaminated soil showed good agreement with the C-14-octadecane mineralisation outcomes. Ratios of n-C-17/pristane and n-C-18/phytane indicated that low nutrient concentrations rather than water were the main limiting factor for biodegradation of hydrocarbons in the soil collected from Old Casey Station when incubated at 10degreesC. However, because the soils from this site are characterised by low water holding capacities, it would be difficult to maintain optimal nutrient concentrations during full-scale treatment, and thus the use of a controlled release nutrient is being considered as a nutrient source in the bioremediation of SAB-contaminated Antarctic soils. Crown Copyright (C) 2003 Published by Elsevier B.V. All rights reserved.