Evidence of molybdenum association with particulate organic matter under sulfidic conditions

T. W. Dahl*, Anthony Chappaz, J.B. Hoek, Christine J. McKenzie, S. Svane, D. E. Canfield

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

    85 Citations (Scopus)

    Abstract

    The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented by sulfate-reducing bacteria). Molybdenum was immobilized at the surface of both living cells and dead/lysed cells, but not in cell-free control experiments. Experiments were carried out at four different Mo concentrations (0.1 to 2 mm) to yield cell-associated Mo precipitates with little or no Fe, consisting of mainly Mo(IV)-sulfide compounds with molecular structures similar to Mo enzymes and to those found in natural euxinic sediments. Therefore, we propose that Mo removal in natural sulfidic waters can proceed via a non-Fe-assisted pathway that requires particulate organic matter (dead or living sulfate-reducing bacteria). This pathway has implications for global marine Mo cycling and the current use of Mo-based proxies for paleo-environmental investigations.

    Original languageEnglish
    JournalGeobiology
    Volume15
    Issue number2
    Pages (from-to)311-323
    Number of pages13
    ISSN1472-4677
    DOIs
    Publication statusPublished - 2017

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