Evidence of molybdenum association with particulate organic matter under sulfidic conditions

TY - JOUR

T1 - Evidence of molybdenum association with particulate organic matter under sulfidic conditions

AU - Dahl, T. W.

AU - Chappaz, Anthony

AU - Hoek, J.B.

AU - McKenzie, Christine J.

AU - Svane, S.

AU - Canfield, D. E.

PY - 2017

Y1 - 2017

N2 - 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.

AB - 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.

U2 - 10.1111/gbi.12220

DO - 10.1111/gbi.12220

M3 - Journal article

C2 - 27997756

AN - SCOPUS:85007382095

SN - 1472-4677

VL - 15

SP - 311

EP - 323

JO - Geobiology

JF - Geobiology

IS - 2

ER -