Conclusion

A number of soil treatment methods are available for cleanup of petroleum contamination in cold regions; few are permissible or practical for Antarctic use. In general, ex situ and in situ methods are limited to the warm season; longer annual treatment is possible inside warmed remediation enclosures. Considerable research and experience has shown that bioremediation offers the most acceptable balance between treatment cost and duration. Landfarming and thermally enhanced bioremediation are sufficiently developed technologies for seasonal use in the Arctic and Antarctica. With engineered bioremediation, it is possible to manipulate the treatment regime and lengthen the annual period of effective treatment at reasonable cost.

Further work is needed to establish the merits of monitored natural attenuation for soil treatment in cold regions. While this method offers a potential low-cost strategy for long-term remediation of sub-Arctic, sub-Antarctica and alpine petroleum-contaminated sites, its limitations and practicality are unknown. Effectiveness of this method is highly dependent on environmental conditions.

Definitive research is needed to establish the consequences of bioaugmentation use in the environment. We simply do not know anything about the potential impacts on soil ecology and the vulnerability of tundra and taiga to potentially invasive microorganisms. Bioaugmentation with non-indigenous or genetically modified/ engineered microorganisms is banned in Antarctica, Norway, Iceland, and Sweden.

Various methods have been employed for ex situ treatment of hydrocarbon-contaminated groundwater (i.e., pump and treat) in cold regions. Because of their relatively high costs associated with continuous operation and maintenance, interest has grown in testing in situ treatment alternatives. However, in situ alternatives are either in the process of development as emerging technologies, or their applicability for cold regions is not yet well-established.

Methods that have been used for in situ chemical and physical treatment of hydrocarbon-contaminated groundwater in cold regions include the construction of vertical barriers to restrict the flow of contaminated water, and the use of multiphase extraction and vacuum-enhanced recovery. The use of permeable reactive barriers to sorb hydrocarbons dissolved in groundwater has been proposed and laboratory- and field-tested.

Methods of in situ biological treatment that have been investigated for potential application in cold regions include biosparging, bioventing (to simultaneously treat soil and groundwater), and intrinsic bioremediation. The later method uses natural, unassisted biodegradation of hydrocarbons by microorganisms in groundwater. Evidence is growing that intrinsic biodegradation of petroleum hydrocarbons in groundwater may be viable for cold regions.

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