The molecular mechanism of Mo isotope fractionation during adsorption to birnessite

Geochimica et Cosmochimica Acta
By: , and 

Links

Abstract

Fractionation of Mo isotopes during adsorption to manganese oxides is a primary control on the global ocean Mo isotope budget. Previous attempts to explain what drives the surprisingly large isotope effect ??97/95Modissolved-??97/95Moadsorbed=1.8??? have not successfully resolved the fractionation mechanism. New evidence from extended X-ray absorption fine structure analysis and density functional theory suggests that Mo forms a polymolybdate complex on the surfaces of experimental and natural samples. Mo in this polynuclear structure is in distorted octahedral coordination, while Mo remaining in solution is predominantly in tetrahedral coordination as MoO42- Our results indicate that the difference in coordination environment between dissolved Mo and adsorbed Mo is the cause of isotope fractionation. The molecular mechanism of metal isotope fractionation in this system should enable us to explain and possibly predict metal isotope effects in other systems where transition metals adsorb to mineral surfaces. ?? 2011 Elsevier Ltd.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The molecular mechanism of Mo isotope fractionation during adsorption to birnessite
Series title Geochimica et Cosmochimica Acta
DOI 10.1016/j.gca.2011.06.020
Volume 75
Issue 17
Year Published 2011
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Geochimica et Cosmochimica Acta
First page 5019
Last page 5031