An Investigation of the Biogeochemistry of Cobalt in the Upper Ocean

EPA Grant Number: U914996
Title: An Investigation of the Biogeochemistry of Cobalt in the Upper Ocean
Investigators: Saito, Mak
Institution: Massachusetts Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1996 through November 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text |  Recipients Lists
Research Category: Fellowship - Oceanography , Aquatic Ecosystems , Academic Fellowships


The objective of this research project is to use electrochemical/analytical work, culture work, and field work to explore the biogeochemistry of cobalt in the Sargasso. Cobalt is an important micronutrient for marine phytoplankton, and it is part of several current hypothesis about the ecology and biogeochemistry of the oceans. Yet, the biogeochemistry of cobalt in the upper ocean has not been explored. In particular, the organic complexation of cobalt, the strength and kinetics of the ligands, and biogenic sources of cobalt ligands are promising areas of future research.


Our preliminary culture data suggests that the abundant marine picoplankter Prochlorococcus marinus is producing a strong specific ligand for cobalt and that P . marinus has an absolute requirement for cobalt. Competitive ligand exchange-cathodic stripping voltammetry, in conjunction with culture work, will test the hypothesis that P . marinus is a source of cobalt ligands. The analytical measurements of total and complexed cobalt in seawater, the bottle incubations manipulating dissolved CO 2 , and trace metals (Co, Fe, Ni, Zn, and Cd) will investigate the hypothesis that distributions of trace metals influence the ecology of Prochlorococcus and Synecho co ccus .

Improvements in our understanding of cobalt and metal biogeochemistry and concomitant measurements of phytoplankton distributions will give insight into other current hypotheses such as the Sunda Scenario (Sunda and Huntsman, 1995), C-Co-Zn colimitation (Morel , et al., 1994), and the influences of trace metal speciation on relative phytoplankton abundances.

Supplemental Keywords:

fellowship, cobalt, marine phytoplankton, upper ocean, Prochlorococcus marinus , cobalt ligands, trace metal speciation., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Oceanography, Aquatic Ecosystem, Biochemistry, Ecology and Ecosystems, marine food web, nutrient dynamics, oceanic phytoplankton, environmental awareness, cobalt, aquatic food web, biogeochemcial cycling, phytoplankton, aquatic ecosystems

Progress and Final Reports:

  • 1996
  • 1997
  • 1998
  • Final