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Variability in the freshwater balance of northern Marguerite Bay, Antarctic Peninsula: results from δ18O

Meredith, Michael P.; Brandon, Mark A.; Wallace, Margaret I.; Clarke, Andrew; Leng, Melanie J.; Renfrew, Ian A.; Van Lipzig, Nicole P.M.; King, John C.. 2008 Variability in the freshwater balance of northern Marguerite Bay, Antarctic Peninsula: results from δ18O. Deep Sea Research II, 55 (3-4). 309-322. 10.1016/j.dsr2.2007.11.005

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Abstract/Summary

We investigate the seasonal variability in freshwater inputs to the Marguerite Bay region (Western Antarctic Peninsula) using a time series of oxygen isotopes in seawater from samples collected in the upper mixed layer of the ocean during 2002 and 2003. We find that meteoric water, mostly in the form of glacial ice melt, is the dominant freshwater source, accounting for up to 5% of the near-surface ocean during the austral summer. Sea ice melt accounts for a much smaller percentage, even during the summer (maximum around 1%). The seasonality in meteoric water input to the ocean (around 2% of the near-surface ocean) is not dissimilar to that of sea ice melt (around 2% in 2002 and 1% in 2003), contradicting the assumption that sea ice processes dominate the seasonal evolution of the physical ocean environment close to the Antarctic continent. Three full-depth profiles of oxygen isotopes collected in successive Decembers (2001, 2002 and 2003) indicate that around 4 m of meteoric water is present in the water column at this time of year, and around 1 m of sea ice formed from this same water column. The predominance of glacial melt is significant, since it is known to be an important factor in the operation of the ecosystem, for example by providing a source of nutrients and modifying the physical environment to control the spatial extent and magnitude of phytoplankton blooms. The Western Antarctic Peninsula is undergoing a very rapid change in climate, with increasing ocean and air temperatures, retreating glaciers and increases in precipitation associated with changes in atmospheric circulation. As climate change continues, we expect meteoric water inputs to the adjacent ocean to rise further. Sea ice in this sector of the Antarctic has shown a climatic decrease, thus we expect a reduction in oceanic sea ice melt fractions if this change continues. Continued monitoring of the oceanic freshwater budget at the western Peninsula is needed to track these changes as they occur, and to better understand their ecological consequences.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.dsr2.2007.11.005
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Long-Term Monitoring and Survey – Biological Sciences Division
BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Antarctic Climate and the Earth System
ISSN: 0967-0645
Additional Keywords: West Antarctic Peninsula, freshwater balance, oxygen isotopes, glacial melt, sea ice
NORA Subject Terms: Marine Sciences
Meteorology and Climatology
Glaciology
Date made live: 07 Mar 2008 13:27
URI: http://nora.nerc.ac.uk/id/eprint/1681

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