• Login
    About WHOAS
    View Item 
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of WHOASCommunities & CollectionsBy Issue DateAuthorsTitlesKeywordsThis CollectionBy Issue DateAuthorsTitlesKeywords

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    The biogeochemistry of cobalt in the Sargasso Sea

    Thumbnail
    View/Open
    Saito_thesis.pdf (10.37Mb)
    Date
    2001-02
    Author
    Saito, Mak A.  Concept link
    Metadata
    Show full item record
    Citable URI
    https://hdl.handle.net/1912/3041
    Location
    Sargasso Sea
    DOI
    10.1575/1912/3041
    Keyword
     Biogeochemistry; Cobalt; Marine phytoplankton; Cyanobacteria; Oceanus (Ship : 1975-) Cruise OC349 
    Abstract
    Processes that enable marine phytoplankton to acquire trace metals are fundamental to our understanding of primary productivity and global carbon cycling. This thesis explored the biogeochemistry of cobalt using analytical chemistry and physiological experiments with the dominant phytoplankton species, Prochlorococcus. A high sensitivity method for Co speciation was developed using hanging mercury drop cathodic stripping voltammetry. Dissolved Co at the Bermuda Atlantic Time Series station (BATS) in the Sargasso Sea was bound by strong organic complexes with a conditional stability constant of logK=16.3l0.9. A depth profile of Co at BATS revealed a nutrient-like profile. Biweekly time series measurements of total cobalt near Bermuda from the MITESS sampler were 0-47pM throughout 1999, and averaged 20±10pM in 1999. A transect of total cobalt from BATS to American coastal waters ranged from 19- 133pM and correlated negatively with salinity (r2=0.93), suggestive of coastal waters as an input source. Prochlorococcus strains MED4-Ax and SS120 showed an absolute requirement for Co, despite replete Zn. 57Co uptake rates and growth rates were enhanced by additions of filtered low Co cultures, suggesting that a ligand is present that facilitates Co uptake. Bottle incubations from a Synechococcus bloom in the Pacific showed production of 425pM strong cobalt ligand. These and other lines of evidence support the hypothesis that a cobalt ligand, or cobalophore, is involved in cobalt uptake. Co-limited Prochlorococcus cultures exhibited an increase in the fraction of cells in G2 relative to other cell cycle stages during exponential growth, and the durations of this stage increased with decreasing cobalt concentrations. This effect was not observed with Fe, N, or P-limited cultures, suggestive of a specific biochemical function of cobalt that would interfere with the late stages of the cell cycle. The ligand Teta was explored as a means to induce cobalt limitation. The CoTeta complex was not bioavailable to the Sargasso Sea microbial assemblage in short-term experiments. Bottle incubations with Teta did not induce cobalt limitation of Prochlorococcus. These results are consistent with the lower conditional stability constant for CoTeta (logK=11.2l0.1) relative to natural cobalt ligands in seawater, and with culture studies that suggest uptake of cobalt via strong organic ligands.
    Description
    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2001
    Collections
    • WHOI Theses
    • Marine Chemistry and Geochemistry (MC&G)
    Suggested Citation
    Thesis: Saito, Mak A., "The biogeochemistry of cobalt in the Sargasso Sea", 2001-02, DOI:10.1575/1912/3041, https://hdl.handle.net/1912/3041
     

    Related items

    Showing items related by title, author, creator and subject.

    • Thumbnail

      Relating the biogeochemistries of zinc, cobalt, and phosphorus to phytoplankton activities in the sea 

      Wisniewski, Rachel J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006-06)
      This thesis explores the potential of zinc, cobalt, and phosphorus to influence primary production in the subarctic North Pacific, the Bering Sea, and the North Atlantic Ocean, In the North Pacific and Bering Sea, total ...
    • Thumbnail

      The role of external inputs and internal cycling in shaping the global ocean cobalt distribution : insights from the first cobalt biogeochemical model 

      Tagliabue, Alessandro; Hawco, Nicholas J.; Bundy, Randelle M.; Landing, William M.; Milne, Angela; Morton, Peter L.; Saito, Mak A. (John Wiley & Sons, 2018-04-16)
      Cobalt is an important micronutrient for ocean microbes as it is present in vitamin B12 and is a co‐factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is ...
    • Thumbnail

      Cobalt, manganese, and iron near the Hawaiian Islands : a potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid-type trace metals 

      Noble, Abigail E.; Saito, Mak A.; Maiti, Kanchan; Benitez-Nelson, Claudia R. (2007-09-26)
      The vertical distributions of cobalt, iron, and manganese in the water column were studied during the E-Flux Program (E-Flux II and III), which focused on the biogeochemistry of cold-core cyclonic eddies that form in the ...
    All Items in WHOAS are protected by original copyright, with all rights reserved, unless otherwise indicated. WHOAS also supports the use of the Creative Commons licenses for original content.
    A service of the MBLWHOI Library | About WHOAS
    Contact Us | Send Feedback | Privacy Policy
    Core Trust Logo