Chasing iron bioavailability in the Southern Ocean: Insights from Phaeocystis antarctica and iron speciation: Bioassays, iron speciation, and isotopic analysis uncover a significant range of variability in dissolved iron bioavailability in the Southern Ocean
- Fourquez, Marion
- Janssen, David, J
- Conway, Tim, M
- Cabanes, Damien
- Ellwood, Michael, J
- Sieber, Matthias
- Trimborn, Scarlett
- Hassler, Christel
DOIAbstract
International audienceDissolved iron (dFe) availability limits the uptake of atmospheric CO 2 by the Southern Ocean (SO) biological pump. Hence, any change in bioavailable dFe in this region can directly influence climate. On the basis of Fe uptake experiments with Phaeocystis antarctica , we show that the range of dFe bioavailability in natural samples is wider (<1 to ~200% compared to free inorganic Fe′) than previously thought, with higher bioavailability found near glacial sources. The degree of bioavailability varied regardless of in situ dFe concentration and depth, challenging the consensus that sole dFe concentrations can be used to predict Fe uptake in modeling studies. Further, our data suggest a disproportionately major role of b...
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