Aquatic Geochemistry

, Volume 3, Issue 4, pp 357–389

The Influence of Redox Reactions on the Uptake of Dissolved Ce by Suspended Fe and Mn Oxide Particles

  • Eric Heinen De Carlo
  • Xi-Yuan Wen
  • Mark Irving
Article

DOI: 10.1023/A:1009664626181

Cite this article as:
De Carlo, E.H., Wen, XY. & Irving, M. Aquatic Geochemistry (1997) 3: 357. doi:10.1023/A:1009664626181

Abstract

Laboratory experiments were conducted to evaluate the partitioning ofrare earth elements (REE) between solution and suspended particles. Becauseof their strong tendency to complex, the REE can be used to study a varietyof marine processes and in particular particle scavenging. In this study, anemphasis was placed on examining abiotic redox processes that influence theuptake of dissolved Ce by particles. Batch sorption experiments wereconducted with REE and synthetic mineral phases over the range of pH4–9. The solutions varied in ionic strength between 0 and 0.7 M andconsisted of individual solutes (NaNO3, NaCl, andNa2SO4), ionic mixtures that duplicate theseawater composition, and natural seawater. The uptake of REE from solutionwas also studied at a Pt electrode coated with \(\delta {\text{ - MnO}}_{\text{2}} \)using cyclic voltametry.

Experimental results are consistent with uptake of dissolved Ce onto\(\delta {\text{ - MnO}}_{\text{2}} \) occurring by a combination of oxidativescavenging and surface complexation. The contribution of oxidativescavenging to the removal of Ce from solution is most pronounced at acidicpH, where the strictly trivalent REE exhibit little propensity for sorptiononto \(\delta {\text{ - MnO}}_{\text{2}} \). Sorption of dissolved Ce onto FeOOH occursin a manner analogous to that of the other strictly trivalent REE and nocontribution from oxidative scavenging is observed on this mineral phase atlow pH. Our work also substantiates the hypothesis that anions in solution,particularly \({\text{SO}}_{\text{4}}^{{\text{2}} - } \) and Cl-, aswell as those adsorbed on the surface of the particles, influence the extentof Ce uptake by \(\delta {\text{ - MnO}}_{\text{2}} \).

Iron oxidemanganese oxideoxidation-reductionparticlesrare earth elementsscavengingseawater

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Eric Heinen De Carlo
    • 1
  • Xi-Yuan Wen
    • 1
  • Mark Irving
    • 2
  1. 1.Department of Oceanography, SOESTUniversity of HawaiiHonoluluHawaii
  2. 2.Department of ChemistryUniversity of HawaiiHonoluluHawaii