Abstract

A highly polluted rain event deposited ammonium and nitrate on Midtre Lovenbreen, Svalbard, European High Arctic, during the melt season in June 1999. Quasi-daily sampling of glacial runoff showed elevated ion concentrations of both ammonium (NH(4)(+)) and nitrate (NO(3)(-)), collectively dissolved inorganic nitrogen (DIN) in the two supraglacial meltwater flows, but only elevated NO(3)(-) in the subglacial outburst. Time-series analysis and flow-chemistry modelling showed that supra- and subglacial assimilation of NH(4)(+) were major impacts of this deposition event. Supraglacial assimilation likely occurred while the pollution-event DIN resided within a/the supraglacial slush layer (estimated DIN half-life 40-50 hours, with the lifetime of NO(3)(-) exceeding that of NH(4)(+) by 30%). Potentially, such processes could affect preservation of DIN in melt-influenced ice cores. Subglacial routing of event DIN and its multi-day storage beneath the glacier also enabled significant assimilation of NH(4)(+) to occur here (60% of input), which may have been either released as particulate N later during the melt season, or stored until the following year. Our results complement existing mass-balance approaches to the study of glacial biogeochemistry, show how modelling can enable time-resolved interpretation of process dynamics within the biologically active melt season, and highlight the importance of episodic polluted precipitation events as DIN inputs to Arctic glacial ecosystems.

Published in

Annals of Glaciology
2010, Volume: 51, number: 56, pages: 163-170
Publisher: INT GLACIOL SOC

UKÄ Subject classification

Geosciences, Multidisciplinary


Publication identifier

DOI: https://doi.org/10.3189/172756411795931949

Permanent link to this page (URI)

https://res.slu.se/id/publ/87936