Soluble and Colloidal Iron in the Oligotrophic North Atlantic and North Pacific.

Presents research findings indicating that previously presumed 'dissolved' iron concentrations in the oligotropic North Atlantic and North Pacific are present in colloidal size range. Depletion of soluble iron and iron-binding organic ligand and enrichment at depth; Maximum levels of colloidal iron at the surface; Results suggesting that dissolved iron may be less available to phytoplankton.