HR: 0800h
AN: OS51C-0570    [Abstracts]
TI: Insights Into Phosphate Turnover in the Sargasso Sea From the Oxygen Isotopic Composition of Dissolved Inorganic Phosphate
AU: * McLaughlin, K
EM: karenmcl@pangea.stanford.edu
AF: Stanford University, Dept. of Geological & Environmental Sciences Building 320, Room 118, Stanford, CA 94305-2115 United States
AU: Paytan, A
EM: apaytan@pangea.stanford.edu
AF: Stanford University, Dept. of Geological & Environmental Sciences Building 320, Room 118, Stanford, CA 94305-2115 United States
AB: We explore the variation of phosphate turnover in the oligotropic Sargasso Sea using a novel isotope tracer approach. The exchange of oxygen isotopes on phosphate only occurs due to intracellular biological cycling. As phosphate is cycled through the biomass, the oxygen isotopic composition of dissolved inorganic phosphate will approach the expected isotopic equilibrium between phosphate and water. Thus, the deviation of the oxygen isotopic composition of dissolved inorganic phosphate within a system from the expected equilibrium phosphate oxygen isotopic composition can be used as a tracer for phosphate turnover. Our results indicate that phosphate is largely out of equilibrium within the mix layer but approaches equilibrium at depth. This suggests that either phosphate is not being fully utilized within the surface waters but is fully recycled at depth or that a yet unquantified, isotopically low phosphate source exists in the surface ocean.
DE: 0460 Marine systems (4800)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4845 Nutrients and nutrient cycling (0470, 1050)
DE: 4870 Stable isotopes (0454, 1041)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005