HR: 15:25h
AN: OS23F-08 INVITED     [Abstracts]
TI: Sections of Dissolved Iron and Aluminum in the North Atlantic and the North Pacific: Results from the CLIVAR Repeat Hydrography A16N and P02 Expeditions
AU: * Landing, B
EM: wlanding@mailer.fsu.edu
AF: Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 United States
AU: Measures, C
EM: chrism@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, Honolulu, HI 96822 United States
AU: Buck, C
EM: cbuck@ocean.fsu.edu
AF: Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 United States
AU: Brown, M
EM: mbrown@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, Honolulu, HI 96822 United States
AB: Vertical profiles for dissolved Fe and Al were collected from the 2003 A16N and 2004 P02 expeditions (62 profiles and 76 profiles, respectively). Dissolved Al and Fe were determined by shipboard FIA (and isotope dilution ICP-MS for Fe) on samples collected from 12 depths in the upper 1000 m at each station. Contour plots of the distributions reveal new hydrographic features for both elements that are well resolved by the approximately 1 degree station spacing. Surface water distributions in the North Atlantic show significant inputs of both elements from the deposition of Saharan dust in the equatorial Atlantic. Sub-surface Al enhancement is observed in the North Atlantic "mode" water between 20N and 35N and in the Mediterranean outflow water. Elevated dissolved Fe concentrations (greater than 2nM) are observed between 20N and 5N beneath the Saharan dust plume and are coincident with the nitrate maximum underlying the high productivity upwelling zone off NW Africa. The North Pacific "mode" water is also labeled with dissolved Al, while dissolved Fe concentrations are highest in the western North Pacific as a result of Asian dust input. Surface water dissolved Fe is slightly elevated across most of the P02 section, but decreases to less than 50 pM from 60-150 meters before increasing again with depth due to nutrient-type regeneration. Nitrate:Fe ratios are low in surface waters across most of both sections, but increase to greater than 15,000 mol-N/mol-Fe below 200 meters. When these waters return to the surface via upwelling, Fe should be the limiting nutrient relative to nitrate.
DE: 4805 Biogeochemical cycles (1615)
DE: 4808 Chemical tracers
DE: 4845 Nutrients and nutrient cycling
DE: 4875 Trace elements
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting