Molybdenum Isotope Ratios and Global Ocean Paleoredox

Molybdenum Isotope Ratios and Global Ocean Paleoredox 

Arnold et al. [11]. The isotopic composition of the input to the oceans from continental weathering in this figure is based on the analyses of river water by Archer and Vance [14]. Suboxic and low-sulfide, anoxic sinks were not included in this earliest model of the marine Mo isotope budget. 

Those studies in the second and third categories have clearly demonstrated that robust application of the Mo isotope paleoredox proxy may not be perfectly straightforward and requires careful consideration of at least three complications. First, the isotopic composition of Mo in riverine waters flowing into the ocean is 

Most of the experimental and theoretical work published thus far concerning the Mo isotope paleoredox proxy relates to isotope fractionation during removal of Mo from seawater to the oxic sink, represented by ferromanganese sediments 

Siebert et cd. [12] and Barling and Anbar [13] suggested that the equUibrium isotope fractionation effect during adsorption of Mo on birnessite could result either from equUibration of two chemical species of Mo in solution, followed by adsorption of just one of them, or from fractionation during the adsorption reaction itself, between one aqueous species and one adsorbed species not present in solution. In order to address this, Tossell [21] used quantum mechanical calculations to explore which trace species of aqueous Mo might fractionate from the 

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