Marine Colloids Chapter uri icon

abstract

  • AbstractAquatic colloids, nanoparticles and macromolecules in the 1nm to 1m size range, are characterized by large interfacial energies and scatter light. Colloids are most often separated from seawater through ultrafiltration. They are characterized by physical techniques, such as diffusion, permeation, or light scattering, and can be imaged by atomic force and electron microscopy. Chemically, they are composed mostly of organic macromolecules, which make up 2030% of marine dissolved organic carbon (DOC). Marine colloidal organic matter (COM) contains biologically resistant heteropolycondensations, such as humictype molecules (geopolymers), and products of carbon fixation and consumption such as exopolymeric substances (EPS) excreted by microorganisms. Both geopolymers and biopolymers are amphiphilic with charged and uncharged groups, and contain strong metalbinding ligands, rendering them metal and radionuclide sequestering agents. Therefore, colloids in the ocean can act as vectors of metal and radionuclide removal and of solubilization, depending on the biomolecule, as well as modifiers of metal bioavailability in delicately balanced marine ecosystems. In addition, marine colloids are also important in their response to global change, as they enhance the sinking flux of carbon, and thus, play a role in global carbon cycling.

author list (cited authors)

  • Santschi, P. H.

complete list of authors

  • Santschi, Peter H

Book Title

  • Water Encyclopedia

publisher