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Control of acid polysaccharide production and 234Th and POC export fluxes by marine organisms
Laboratory for Oceanographic and Environmental Research, Department of Oceanography, Texas A&M University, Galveston, TX, USA
Laboratory for Oceanographic and Environmental Research, Department of Oceanography, Texas A&M University, Galveston, TX, USA
Laboratory for Oceanographic and Environmental Research, Department of Oceanography, Texas A&M University, Galveston, TX, USA
Laboratory for Oceanographic and Environmental Research, Department of Oceanography, Texas A&M University, Galveston, TX, USA
International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA
Department of Oceanography, Texas A&M University, College Station, TX, USA
College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
Ratios of particulate organic carbon (POC) to particulate 234Th activities (POC/234Th) in the ocean are used to determine the POC export flux, and thus, the power of the biological pump. In order to understand the main reasons why this ratio frequently varies as a function of depth, size, and kind (suspended vs. sinking particles), we measured vertical profiles in a cold core ring and warm core ring in the Gulf of Mexico in May 2001. Here we show that particulate 234Th/POC ratios in the Gulf of Mexico are positively correlated to the content of different Th(IV)-binding polysaccharide fractions (uronic acids, total acid polysaccharides, total polysaccharides) in both suspended and sinking particles as well as to prymnesiophyte abundance, but negatively correlated to bacterial production. Variations in acid polysaccharide compounds, produced by both algae and bacteria, but degraded only by bacteria, can account for observed variations in POC/234Th ratios seen in the ocean.
Published 21 January 2003.
Citation: (2003), Control of acid polysaccharide production and 234Th and POC export fluxes by marine organisms, Geophys. Res. Lett., 30(2), 1044, doi:10.1029/2002GL016046.
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