In Situ Remediation of Oil Spills in Ice-Packed Waters: Enhanced Dispersion and Biodegradation of Petroleum Hydrocarbons

摘要

There are anticipated increases in marine traffic in the Arctic due to climate change (e.g., extension of the open water season for the Northwest Passage) and industrial operations (e.g., offshore oil and gas exploration/production activities). As a result, the public, industry and regulatory resource managers have demanded improvements in oil spill countermeasures for use in cold regions and ice-covered waters. A novel remediation technique for oil spills in these waters has been proposed based on applying clay mineral particles and the provision of mixing energy from propeller-wash to promote the formation of oil-mineral aggregates (OMA). Results from previous work in the laboratory and field have shown that the formation of OMA is associated with enhanced oil dispersion and degradation. To evaluate the feasibility of this in situ dispersion/ bioremediation strategy in ice-covered waters, a field study was conducted with a Canadian Coast Guard ice-breaker in the St. Lawrence River Estuary (offshore of Matane, Quebec, Canada) in the winter of 2007-2008. The effectiveness of the proposed treatment strategy was evaluated by monitoring the temporal and spatial dynamic changes of petroleum hydrocarbon concentrations and investigating the rate/extent of biodegradation of the petroleum hydrocarbons. Field samples were recovered to set up microcosms in the laboratory to monitor for the biodegradation of total petroleum hydrocarbons (TPH). Results from the analysis of these samples using Gas Chromatography/ Flame Ionization Detection (GC/FID) and Gas Chromatography/Mass Spectrometry (GC/MS) shows that with hopane normalization, almost 60% of the TPH had been degraded after 56 days incubation at low temperature (0.5°C). The results from this field trial support further research to evaluate the feasibility of this technique as an operational oil spill countermeasure under a wide range of environmental conditions and to determine the fate and effects of the petroleum hydrocarbons entrained in OMA in the aquatic environment.