Dye tracing to determine flow properties of hydrocarbon-polluted Rabots glaci?r, Kebnekaise, Sweden

摘要

Over 11 000 L of kerosene was deposited on the surface of Rabotsglaci?r on the Kebnekaise Massif, northern Sweden, following the crash ofa Royal Norwegian Air Force aircraft in March 2012. An environmentalmonitoring programme was subsequently commissioned, including a series of dyetracing experiments during the 2013 melt season, conducted to investigate thetransport of pollutants through the glacier hydrological system. Thisexperimental set-up provided a basis from which we could gain new insightinto the internal hydrological system of Rabots glaci?r. Results of dyetracing experiments reveal a degree of homogeneity in the topology of thedrainage system throughout July and August, with an increase in efficiency asthe season progresses, as reflected by decreasing temporary storage anddispersivity. Early onset of melting likely led to formation of an efficient,discrete drainage system early in the melt season, subject to decreasingsinuosity and braiding as the season progressed. Four distinct meltwater flowregimes are identified to summarize the temporal and spatial evolution of thesystem. Analysis of turbidity-discharge hysteresis further supports theformation of discrete, efficient drainage, with clockwise diurnal hysteresissuggesting easy mobilization of readily available sediments in channels. Dyeinjection immediately downstream of the pollution source zone revealsprolonged storage of dye followed by fast, efficient release. Twinned with alow dye recovery, and supported by sporadic detection of hydrocarbons in theproglacial river, we suggest that meltwater, and thus pollutants in solution,may be released periodically through an efficient, and likely pressurized,hydrological system within the upper reaches of the glacier.