Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Estuarine, Coastal and Shelf Science 87 (2010): 103-112, doi:10.1016/j.ecss.2009.12.017.
Description:
The use of dissolved Al as a tracer for oceanic water masses and atmospheric
dust deposition of biologically important elements, such as iron, requires the
quantitative assessment of its sources and sinks in seawater. Here, we address
the relative importance of oceanic versus atmospheric inputs of Al, and the
relationship with nutrient cycling, in a region of high biological productivity in
coastal Antarctica. We investigate the concentrations of dissolved Al in
seawater, sea ice, meteoric water and sediments collected from northern
Marguerite Bay, off the West Antarctic Peninsula, from 2005-2006. Dissolved Al
concentrations at 15 m water depth varied between 2 and 27 nM, showing a
peak between two phytoplankton blooms. We find that, in this coastal setting,
upwelling and incorporation of waters from below the surface mixed layer are
responsible for this peak in dissolved Al as well as renewal of nutrients. This
means that changes in the intensity and frequency of upwelling events may
result in changes in biological production and carbon uptake. The waters below
the mixed layer are most likely enriched in Al as a result of sea ice formation,
either causing the injection of Al-rich brines or the resuspension of sediments
and entrainment of pore fluids by brine cascades. Glacial, snow and sea ice melt
contributes secondarily to the supply of Al to surface waters. Total particulate
Al ranges from 93 to 2057 μg/g, and increases with meteoric water input
towards the end of the summer, indicating glacial runoff is an important source
of particulate Al. The (Al/Si)opal of sediment core top material is considerably
higher than water column opal collected by sediment traps, indicative of a
diagenetic overprint and incorporation of Al at the sediment-water interface.
Opal that remains buried in the sediment could represent a significant sink of Al
from seawater.
Description:
This project is part of AFI4‐02 and KRH
was funded by NERC grant NER/S/A/2004/12390.
Keywords:
Biogeochemistry
;
Nutrients (mineral)
;
Trace metals
;
Brines
;
Antarctica
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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