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Biogeochemical observations during the winter-spring transition in East Antarctic sea ice: Evidence of iron and exopolysaccharide controls
Citation
Van Der Merwe, P and Lannuzel, D and Mancuso Nichols, CA and Meiners, K and Heil, P and Norman, L and Thomas, DN and Bowie, AR, Biogeochemical observations during the winter-spring transition in East Antarctic sea ice: Evidence of iron and exopolysaccharide controls, Marine Chemistry: An International Journal for Studies of All Chemical Aspects of The Marine Environment, 115, (3-4) pp. 163-175. ISSN 0304-4203 (2009) [Refereed Article]
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DOI: doi:10.1016/j.marchem.2009.08.001
Abstract
This paper documents the spatial distribution and concentration of exopolysaccharides at 9 discrete sea ice
sites, consisting of first year sea ice, and relates this information to physical (ice temperature, texture) and
biogeochemical (oxygen stable isotopic composition of the ice, salinity, macronutrients, dissolved iron,
particulate organic carbon, dissolved organic carbon and Chlorophyll a) variables. The sampling was carried
out over a transition from austral winter to early spring conditions as part of the Sea Ice Physics and
Ecosystems eXperiment (SIPEX), during September/October 2007 in the 110°130° E region off East
Antarctica. Exopolysaccharide concentrations in sea ice varied by 3 orders of magnitude from 2.8 to 2690 μg
xanthan equivalent (xeq.) l−1; basal ice mean 493 μg xeq. l−1. Exopolysaccharides correlated significantly
with particulate organic carbon and Chlorophyll a but not with dissolved iron, dissolved organic carbon or
macronutrient data, indicating that exopolysaccharides are most likely produced in situ by autotrophic sea
ice biota, superimposed over fossil organics. We observed increased exopolysaccharide per unit biomass in
the colder surface to intermediate ice at three stations, supporting the theory that exopolysaccharides may
be used as a cryoprotectant. Mean bulk ice dissolved iron (depth integrated) across all ice cores was 2.37 nM
(range 0.23 to 14.4 nM). Sea ice dissolved iron concentration was always elevated relative to seawater.
Apparent dissolved iron and estimates of cellular carbon to iron ratios suggest that the sea ice microbial biota
was not limited by dissolved iron but may have been by NO2+NO3 or Si(OH)4. Conversely, under ice
seawater algal communities may have been limited by dissolved iron and/or light and grazing at the time of
sampling. We observed a significant inverse correlation between dissolved Fe and Chlorophyll a in the basal
layers of the ice, most likely indicating the active drawdown of dissolved Fe by the sea ice biota, combined
with some fraction lost to the water column or converted to the particulate fraction.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | Antarctica, Sea ice, Biogeochemistry, Exopolysaccharide, Iron |
| Research Division: | Earth Sciences |
| Research Group: | Oceanography |
| Research Field: | Chemical Oceanography |
| Objective Division: | Environment |
| Objective Group: | Physical and Chemical Conditions of Water |
| Objective Field: | Physical and Chemical Conditions of Water in Marine Environments |
| UTAS Author: | Van Der Merwe, P (Dr Pier van der Merwe) |
| UTAS Author: | Lannuzel, D (Associate Professor Delphine Lannuzel) |
| UTAS Author: | Mancuso Nichols, CA (Dr Carol Mancuso Nichols) |
| UTAS Author: | Meiners, K (Dr Klaus Meiners) |
| UTAS Author: | Heil, P (Dr Petra Heil) |
| UTAS Author: | Bowie, AR (Professor Andrew Bowie) |
| ID Code: | 62463 |
| Year Published: | 2009 |
| Web of Science® Times Cited: | 56 |
| Deposited By: | IASOS |
| Deposited On: | 2010-03-12 |
| Last Modified: | 2010-05-04 |
| Downloads: | 2 View Download Statistics |
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