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Modelling the impacts of a nitrogen pollution event on the biogeochemistry of an Arctic glacier

Roberts, Tjarda J.; Hodson, Andy; Evans, Chris D.; Holmen, Kim. 2010 Modelling the impacts of a nitrogen pollution event on the biogeochemistry of an Arctic glacier. Annals of Glaciology, 51 (56). 163-170. 10.3189/172756411795931949

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Abstract/Summary

A highly polluted rain event deposited ammonium and nitrate on Midtre Love´nbreen,Svalbard, European High Arctic, during the melt season in June 1999. Quasi-daily sampling of glacial runoff showed elevated ion concentrations of both ammonium (NH4+) and nitrate (NO3–), collectively dissolved inorganic nitrogen (DIN) in the two supraglacial meltwater flows, but only elevated NO3– in the subglacial outburst. Time-series analysis and flow-chemistry modelling showed that supra- and subglacial assimilation of NH4 + 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 NO3– exceeding that of NH4+ 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 NH4+ 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.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3189/172756411795931949
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes > BGC - 1.3 - Quantify & attribute changes in biogeochemiical cycles ...
CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 2 - Biogeochemistry and Climate System Processes > BGC - 2.1 - Quantify & model processes that control the emission, fate and bioavailability of pollutants
CEH Sections: Emmett
ISSN: 0260-3055
NORA Subject Terms: Glaciology
Ecology and Environment
Date made live: 05 Dec 2011 14:03
URI: http://nora.nerc.ac.uk/id/eprint/15885

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