Aquatic Sciences Meeting, Albuquerque 2001
| CS07 Biogeochemical Cycles |
| Date: Thursday, February 15, 2001, Time: 4:00:00 PM |
| Location: Cochiti/Taos |
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| Hung, C, C, Texas A&M University, Galveston, USA, hungc@tamug.tamu.edu |
| Guo, L, , Texas A&M University, and International Arctic Research Center, University of Alaska, Fairbanks, USA, guol@tamug.tamu.edu |
| Santschi, P, H, Texas A&M University, Galveston, USA, santschi@tamug.tamu.edu |
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| Dissolved and particulate polysaccharides in the Gulf of Mexico |
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| Polysaccharides are some of the most abundant organic biopolymers in seawater and may play a critical role in organic carbon cycling, such as the formation of marine snow flocs, the production of biofilms and mucilaginous aggregates as well as the removal of trace elements and radionuclides from the water. In order to study the role of polysaccharides in marine organic carbon cycling, the concentrations of carbohydrates (CHO) and uronic acids (URA) in both dissolved and particulate phases were measured in the water column of the Gulf of Mexico during July, 2000 aboard R/V Gyre along a transect at 90 degree W, with contrasting oceanographic settings, i.e., across a cold core and a warm core ring. The concentration of dissolved carbohydrates (DCHO) ranged from 2 to 12 umole-C/L and the vertical distribution of DCHO showed a subsurface maximum, which was located slightly above the chl-a maximum layer. The concentration of CHO in suspended particles ranged from 0.03 to 0.3 umole-C/L. The concentrations of CHO (in umole/g of particle mass) in sinking particles were 7 to 12 times higher than those in suspended particles, when normalized to the mass of particles. Similarly, the concentration of URA in sinking particles were 5 to 20 times higher than that in suspended particles. The relative enrichment of CHO and URA in sinking particles compared to suspended particles suggest that the source of CHO and URA in settling particles may be largely through the coagulation of particle-reactive organic components in the water column. Furthermore, physico-chemical processes such as aggregation and coagulation, may control the POC export flux out of the euphotic zone in the upper ocean. |
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