FeCycle: Attempting an iron biogeochemical budget from a mesoscale SF6 tracer experiment in unperturbed low iron waters

Autor: Boyd, P.W., Law, C.S., Hutchins, D.A., Abraham, E.R., Croot, Peter, Ellwood, M., Frew, R.D., Hadfield, M., Hall, Janet, Handy, S., Hare, C.E., Higgins, J., Hill, P., Hunter, K.A., Leblanc, K., Maldonado, M.T., Mckay, R.M., Mioni, C., Oliver, M., Pickmere, S., Pinkerton, M., Safi, K., Sander, S., Sanudo-Wilhelmy, Sergio, Smith, M., Strzepek, R., Tovar-Sanchez, A., Wilhem, S.W.
Přispěvatelé: National Institute of Water and Atmosphere Centre for Chemical and Physical Oceanography, University of Otago [Dunedin, Nouvelle-Zélande], National Institute of Water and Atmospheric Research [Wellington] (NIWA), College of Marine Studies (CMS), University of Delaware [Newark], National Institute of Water and Atmosphere [Hamilton] (NIWA), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Department of Chemistry, Department of microbiology, The University of Tennessee [Knoxville], Department of Earth and Ocean Sciences [Vancouver] (EOS), University of British Columbia (UBC), Department of Biological Sciences [Bowling Green], Bowling Green State University, Marine Sciences Research Center, Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Institut Mediterrani d'Estudis Avancats (IMEDEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de las Islas Baleares (UIB)
Jazyk: angličtina
Rok vydání: 2005
Předmět:
Zdroj: Global Biogeochemical Cycles
Global Biogeochemical Cycles, American Geophysical Union, 2005, 19 (GB4S20), 13 pp. ⟨10.1029/2005GB002494⟩
ISSN: 0886-6236
DOI: 10.1029/2005GB002494⟩
Popis: International audience; An improved knowledge of iron biogeochemistry is needed to better understand key controls on the functioning of high-nitrate low-chlorophyll (HNLC) oceanic regions. Iron budgets for HNLC waters have been constructed using data from disparate sources ranging from laboratory algal cultures to ocean physics. In summer 2003 we conducted FeCycle, a 10-day mesoscale tracer release in HNLC waters SE of New Zealand, and measured concurrently all sources (with the exception of aerosol deposition) to, sinks of iron from, and rates of iron recycling within, the surface mixed layer. A pelagic iron budget (timescale of days) indicated that oceanic supply terms (lateral advection and vertical diffusion) were relatively small compared to the main sink (downward particulate export). Remote sensing and terrestrial monitoring reveal 13 dust or wildfire events in Australia, prior to and during FeCycle, one of which may have deposited iron at the study location. However, iron deposition rates cannot be derived from such observations, illustrating the difficulties in closing iron budgets without quantification of episodic atmospheric supply. Despite the threefold uncertainties reported for rates of aerosol deposition (Duce et al., 1991), published atmospheric iron supply for the New Zealand region is ∼50-fold (i.e., 7- to 150-fold) greater than the oceanic iron supply measured in our budget, and thus was comparable (i.e., a third to threefold) to our estimates of downward export of particulate iron. During FeCycle, the fluxes due to short term (hours) biological iron uptake and regeneration were indicative of rapid recycling and were tenfold greater than for new iron (i.e. estimated atmospheric and measured oceanic supply), giving an "fe" ratio (uptake of new iron/uptake of new + regenerated iron) of 0.17 (i.e., a range of 0.06 to 0.51 due to uncertainties on aerosol iron supply), and an "Fe" ratio (biogenic Fe export/uptake of new + regenerated iron) of 0.09 (i.e., 0.03 to 0.24).
Databáze: OpenAIRE
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