Oil biodegradation in Arctic fjord ice
- a winter field study

The field site at Svea An ice core section containing a bunker oil

It is well known that biodegradation is one of the most important processes for the removal of petroleum hydrocarbons from marine environments. Also in the Arctic environments biodegradation is important, and during summer conditions degradation follows a pattern indistinguishable from that exhibited under temperate climate conditions. However, the necessary knowledge about hydrocarbon biodegradation of oil frozen in Arctic ice is lacking. The ice contains a variety of cold-adapted microorganisms, and metabolic activities have been measured at ice temperatures well below -10°C.  

During a project sponsored by the Research Council of Norway, “Weathering of marine oil spills under Arctic conditions”, interactions between ice microbes and oils are investigated as a part of a winter field study. This project is a collaboration between the University Centre at Svalbard (UNIS), SINTEF Materials and Chemistry, the Norwegian Centre for Air Research (NILU) and the University of Bergen. Different crude or photo-oxidized oils were frozen into Arctic Fjord ice (Van Mijen fjord, Svea, Spitzbergen) in February 2004, and ice cores were collected in March and April (Fig. 1). The ice cores (1 m long) were thawed at the field laboratory of SINTEF in Svea. Each core was separated in sections, the upper section containing the oil. All sections have been processed for microbiological analysis at SINTEF, including various microscopic analysis, counts of actively colony-forming microbes, and characterization of microbial communities by 16S rRNA gene PCR-DGGE, and by cloning-sequencing strategies.

Preliminary results show strong indications of interactions between oils and the microbial communities in the ice. Enumerations of microbes in the ice sections by epifluorescence microscopy and by fluorescence in situ hybridization (FISH) analysis revealed that bacterial concentrations were significantly higher in the top sections of the ice, containing the frozen oil, than deeper in the ice. No such patterns were measured in clean ice (Fig 2). These results were obtained in ice samples after 2 months of oil pollution, and no significant differences were measured between various oils.

Further chemical characterization of the frozen oil at UNIS will elucidate possible biodegradation patterns in the various oils.

Contact at SINTEF Materials and Chemistry: Odd Gunnar Brakstad

Total numbers of microbes, bacteria and archaea enumerated in thawed ice from non-polluted ice cores, and from ice cores polluted with a paraffinic oil for 2 months. Results are shown for the ice top sections (0-25 cm), middle sections (25-60 cm) and bottom sections (60-100 cm). Microbes were enumerated by epifluorescence microscopy with the fluorochrome DAPI (total counts), or by FISH with specific DNA probes for bacteria (EUB338) and archaea (ARCH915).