CS26 Organic Carbon Dynamics
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
KrembsC-, Applied Physics Laboratory, University of Washington, Seattle, USA, ckrembs@ocean.washington.edu
Deming, J, W, School of Oceanography, University of Washington, Seattle, USA, jdeming@u.washington.edu
Eicken, H, -, Geophysical Institute, University of Alaska, Fairbanks, USA, 
 
METHODOLOGICAL APPROACHES TO MEASURING THE ORGANIC MATTER POOL IN ARCTIC SEA ICE: SIGNIFICANCE OF EXO-POLYSACCHARIDES AT THE SPRING-SUMMER TRANSITION
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The dynamics of organic matter inside sea ice is little understood, yet important for the survival of microorganisms in the very cold and briny environments between ice crystals. Because exo-polysaccharides can buffer cells against osmotic stress and encroaching ice crystals, this class of organic compounds is under a new scrutiny. We collected sea ice from the Chukchi Sea (Barrow, Alaska), shortly after collapse of the bottom-ice diatom bloom (Chl a, 18 g/L; phaeophytin, 39 ug/L) in June 2001, and compared approaches for polysaccharide analysis using the Alcian blue, phenol sulfuric acid, and MBTH methods. Results agreed strongly (r = 0.969, p < 0.0001), though sensitivities differed among methods. Mass M.W. fractionations indicated four peaks of polysaccharides over the range of 3-183 kD. Microscopic examination of ice thin sections after in situ staining confirmed a polymer-pennate diatom association. Highest polysaccharide concentrations in the particulate gel-size fraction (0.4 um; e.g. 9124 ug XGEQV/L) coincided with the Chl a max and the location of most of the POC (max, 3.12 mg/L) and DOC (max, 535 uM) in the lowermost 10 cm of the ice.