Physical Responses to Anthropogenic Disturbance on a Runway in the Canadian High Arctic.

Background: The McGill Arctic Research Station (MARS) runway on Axel Heiberg Island, Nunavut has been subject to intense compaction from aircrafts since the 1960's, causing alterations to the landscape across time and space. This study investigated the thermal, hydrological and physical responses of repeated aircraft compaction of the runway to characterize its vulnerability to land use, and the effects of long-term and repeated compaction. Methods: In late July and early August 2018, the island's summer thaw season, topographic, soil, hydrological and frost table data were collected along four transects across the MARS runway. Results: Topography and effective porosity differences caused by compaction were found to affect soil moisture contents, leading to the observed differential frost heaving and insulation properties of soil across the runway. Soil was found to be mostly silt on and off disturbed areas, indicating that compaction does not affect grain-size but rather pore space and soil bulk density. The frost table mapping suggested statistically significant variations in depth of the frost table across undisturbed, disturbed, and indirectly disturbed areas, showing that compression from aircrafts has both direct and indirect spatial impacts on the hydrogeomorphic system. Furthermore, this research examined possible solutions to mitigate thaw consolidation of the runway. Limitations: The method of probing used to determine frost table depths introduced significant error to the data. Probing discrepancies arose between people probing and between sampling days, as techniques differed and/or improved. Future studies should consider using electrical resistance tomography to map the frost table, as this would eliminate inconsistencies. Furthermore, white pore size distributions were inferred based on grain-size and extent of compaction, subsequent studies should consider a quantitative approach to pore space analysis. Conclusion: This study suggests that aircraft travel to the remote McGill Arctic Research Station causes spatially and temporally significant changes in the local hydrogeomorphology, especially in fine-grained and wet, frost-susceptible soils. Thaw consolidation, which results indicate is caused by the direct and indirect effects of soil compaction, compromises the prolonged use of the runway. [ABSTRACT FROM AUTHOR]