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The characteristics of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) in Antarctic sea ice
Citation
Norman, L and Thomas, DN and Stedmon, CA and Granskog, MA and Papadimitriou, S and Krapp, RH and Meiners, KM and Lannuzel, D and Van Der Merwe, P and Dieckmann, GS, The characteristics of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) in Antarctic sea ice, Deep-Sea Research. Part 2: Topical Studies in Oceanography, 58, (9-10) pp. 1075-1091. ISSN 0967-0645 (2011) [Refereed Article]
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Copyright Statement
Copyright © 2010 Elsevier Ltd The definitive version is available at http://www.sciencedirect.com
DOI: doi:10.1016/j.dsr2.2010.10.030
Abstract
An investigation of coloured dissolved organic matter (CDOM) and its relationships to physical and
biogeochemical parameters in Antarctic sea ice and oceanic water have indicated that ice melt may both
alter the spectral characteristics of CDOM in Antarctic surface waters and serve as a likely source of fresh
autochthonous CDOM and labile DOC. Samples were collected from melted bulk sea ice, sea ice brines,
surface gap layer waters, and seawater during three expeditions: one during the spring to summer and
two during the winter to spring transition period. Variability in both physical (temperature and salinity)
and biogeochemical parameters (dissolved and particulate organic carbon and nitrogen, as well as
chlorophyll a) was observed during and between studies, but CDOMabsorption coefficients measured at
375 nm (a375) did not differ significantly. Distinct peaked absorption spectra were consistently observed
for bulk ice, brine, and gap water, but were absent in the seawater samples. Correlation with the measured
physical and biogeochemical parameters could not resolve the source of these peaks, but the shoulders
and peaks observed between 260 and 280 nmand between 320 to 330 nmrespectively, particularly in the
samples taken from high light-exposed gap layer environment, suggest a possible link to aromatic and
mycosporine-like amino acids. Sea ice CDOM susceptibility to photo-bleaching was demonstrated in an
in situ 120 hour exposure, during which we observed a loss in CDOM absorption of 53% at 280 nm, 58% at
330 nm, and 30% at 375 nm. No overall coincidental loss of DOC or DON was measured during the
experimental period. A relationship between the spectral slope (S) and carbon-specific absorption (an
375)
indicated that the characteristics of CDOM can be described by the mixing of two broad end-members;
and aged material, present in brine and seawater samples characterised by high S values and low an
375; and
a fresh material, due to elevated in situ production, present in the bulk ice samples characterised by low S
and high an
375. The DOC data reported here have been used to estimate that approximately 8 Tg C yr-1
(~11% of annual sea ice algae primary production) may be exported to the surface ocean during seasonal
sea ice melt in the form of DOC.
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | Sea ice;Antarctic;Coloured dissolved organic matter (CDOM); Dissolved organic matter (DOM); Photochemistry; Biogeochemistry |
Research Division: | Environmental Sciences |
Research Group: | Ecological applications |
Research Field: | Ecosystem function |
Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
Objective Group: | Understanding climate change |
Objective Field: | Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts) |
UTAS Author: | Meiners, KM (Dr Klaus Meiners) |
UTAS Author: | Lannuzel, D (Associate Professor Delphine Lannuzel) |
UTAS Author: | Van Der Merwe, P (Dr Pier van der Merwe) |
ID Code: | 72229 |
Year Published: | 2011 |
Web of Science® Times Cited: | 55 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2011-08-24 |
Last Modified: | 2022-08-25 |
Downloads: | 0 |
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