Iron profiles and speciation of the upper water column at the Bermuda Atlantic time-series Study site: a model based sensitivity study

Weber, L.; Völker, Christoph; Oschlies, Andreas; Burchard, Hans

doi:10.5194/bgd-4-823-2007

Cited by 14 publications

(27 citation statements)

References 60 publications

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“…A previous study of cellular iron in Crocosphaera watsonii observed an increase in iron concentrations per cell during the dark period (15). Our calculated iron per cell attributed to nitrogen fixation and photosynthesis are roughly consistent with measured values (15), and the higher iron content at night likely results from diel proteome cycling with the added contributions of daytime uptake and accumulation of ferrous iron (21) produced by photochemical reduction (40) and photoperiod cell division (Fig. S4).…”

Section: Resultssupporting

confidence: 74%

Iron conservation by reduction of metalloenzyme inventories in the marine diazotroph Crocosphaera watsonii

Saito¹,

Bertrand²,

Dutkiewicz

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

204

228

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The marine nitrogen fixing microorganisms (diazotrophs) are a major source of nitrogen to open ocean ecosystems and are predicted to be limited by iron in most marine environments. Here we use global and targeted proteomic analyses on a key unicellular marine diazotroph Crocosphaera watsonii to reveal large scale diel changes in its proteome, including substantial variations in concentrations of iron metalloproteins involved in nitrogen fixation and photosynthesis, as well as nocturnal flavodoxin production. The daily synthesis and degradation of enzymes in coordination with their utilization results in a lowered cellular metalloenzyme inventory that requires ∼40% less iron than if these enzymes were maintained throughout the diel cycle. This strategy is energetically expensive, but appears to serve as an important adaptation for confronting the iron scarcity of the open oceans. A global numerical model of ocean circulation, biogeochemistry and ecosystems suggests that Crocosphaera's ability to reduce its iron-metalloenzyme inventory provides two advantages: It allows Crocosphaera to inhabit regions lower in iron and allows the same iron supply to support higher Crocosphaera biomass and nitrogen fixation than if they did not have this reduced iron requirement.cyanobacteria | marine iron cycle | nitrogen cycle

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Section: Resultssupporting

confidence: 74%

Iron conservation by reduction of metalloenzyme inventories in the marine diazotroph Crocosphaera watsonii

Saito¹,

Bertrand²,

Dutkiewicz

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

204

228

View full text Add to dashboard Cite

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“…A simple kinetic model to describe the concentrations of Fe(II), Fe(III), O − 2 , and H 2 O 2 in experiment 3 was developed on the basis of Weber et al (2007), similar also to Meunier et al (2005) or Rose and Waite (2003c). Processes included in the model are listed in Table 1, together with the assumed rate constants for the reactions.…”

Section: Numerical Modelmentioning

confidence: 99%

The role of polysaccharides and diatom exudates in the redox cycling of Fe and the photoproduction of hydrogen peroxide in coastal seawaters

et al. 2010

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Abstract. The effect of artificial acidic polysaccharides (PS) and exudates of Phaeodactylum tricornutum on the half-life of Fe(II) in seawater was investigated in laboratory experiments. Strong photochemical hydrogen peroxide (H 2 O 2 ) production of 5.2 to 10.9 nM (mg C) −1 h −1 was found in the presence of PS and diatom exudates. Furthermore when illuminated with UV light the presence of algal exudates had a net stabilising effect on ferrous iron in seawater (initial value 100 nmol L −1 ) above that expected from oxidation kinetics. In the dark the PS gum xanthan showed no stabilising effect on Fe(II). The photochemical formation of superoxide (O − 2 ) in the presence of diatom exudates and its reducing effect on Fe(III) appears to result in greater than expected concentrations of Fe(II). A model of the photochemical redox cycle of iron incorporating these processes supported the observed data well. Diatom exudates seem to have the potential to play an important role for the photochemistry of iron in coastal waters.

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“…Based on recent studies on Fe speciation and the existing model for the Bermuda Atlantic Time-series Study (BATS) (Weber et al, 2007), this model aims at studying the role of dust particles in Fe removal and providing a better description of the sources and fate of organic Fe-binding ligands.…”

Section: Atmospheric Deposition -Dustmentioning

confidence: 99%

Iron biogeochemistry across marine systems – progress from the past decade

et al. 2010

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Abstract. Based on an international workshop (Gothenburg, 14-16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.Correspondence to: E. Breitbarth (ebreitbarth@chemistry.otago.ac.nz)

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Iron profiles and speciation of the upper water column at the Bermuda Atlantic time-series Study site: a model based sensitivity study

Cited by 14 publications

References 60 publications

Iron conservation by reduction of metalloenzyme inventories in the marine diazotroph Crocosphaera watsonii

Iron conservation by reduction of metalloenzyme inventories in the marine diazotroph Crocosphaera watsonii

The role of polysaccharides and diatom exudates in the redox cycling of Fe and the photoproduction of hydrogen peroxide in coastal seawaters

Iron biogeochemistry across marine systems – progress from the past decade

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