Fe isotopic fractionation during mineral dissolution with and without bacteria

Brantley, Susan L.; Liermann, Laura J.; Guynn, R. L.; Anbar, Ariel D.; Icopini, Gary A.; Barling, Jane

doi:10.1016/j.gca.2004.01.023

Cited by 231 publications

(200 citation statements)

References 47 publications

(97 reference statements)

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“…With the assumption that the DFe sink at both depths (intermediate and deep) is dominated by the same scavenging process (2,39,40), then our observations suggest that the processes dominating the DFe sources in the deep ocean layers are not organic matter remineralization given the heavier DFe isotopic signatures uncovered. At depth, non-reductive release of DFe from particles (3,10,11,17) could produce the observed isotopically heavier DFe, potentially through the following: (i) desorption as suggested for thorium and protactinium (5), rare earth elements (6) or copper (7), or (ii) ligand (siderophore)-promoted dissolution (42). This hypothesis is supported by the recent documentation of the isotopic signature of a labile fraction of suspended particles (from the North Atlantic), for which typical values are found around −0.3‰ (43).…”

Section: Discussionmentioning

confidence: 99%

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

Abadie

Lacan

Radic

et al. 2017

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

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As an essential micronutrient, iron plays a key role in oceanic biogeochemistry. It is therefore linked to the global carbon cycle and climate. Here, we report a dissolved iron (DFe) isotope section in the South Atlantic and Southern Ocean. Throughout the section, a striking DFe isotope minimum (light iron) is observed at intermediate depths (200–1,300 m), contrasting with heavier isotopic composition in deep waters. This unambiguously demonstrates distinct DFe sources and processes dominating the iron cycle in the intermediate and deep layers, a feature impossible to see with only iron concentration data largely used thus far in chemical oceanography. At intermediate depths, the data suggest that the dominant DFe sources are linked to organic matter remineralization, either in the water column or at continental margins. In deeper layers, however, abiotic non-reductive release of Fe (desorption, dissolution) from particulate iron—notably lithogenic—likely dominates. These results go against the common but oversimplified view that remineralization of organic matter is the major pathway releasing DFe throughout the water column in the open ocean. They suggest that the oceanic iron cycle, and therefore oceanic primary production and climate, could be more sensitive than previously thought to continental erosion (providing lithogenic particles to the ocean), particle transport within the ocean, dissolved/particle interactions, and deep water upwelling. These processes could also impact the cycles of other elements, including nutrients.

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Section: Discussionmentioning

confidence: 99%

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

Abadie

Lacan

Radic

et al. 2017

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

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“…Experimental data on aqueous Fe species, Fe-oxides and Fe-carbonates have been documented and demonstrate that the largest Fe isotope fractionations are produced during redox reactions in both biologically mediated (Brantley et al, 2001Anbar, 2004;Johnson et al, 2004;Beard et al, 1999Beard et al, ,2003Icopini et al, 2004;Croal et al, 2004) and abiotic systems (Anbar et al, 2000;Skulan et al, 2002Brantley et al, 2004Welch et al, 2003;Matthews et al, 2004;Teutsch et al, 2005;Jang et al, 2008, Handler et al, 2009McAnena, 2009, Beard et al, 2010. Smaller, but significant fractionations have been seen in abiotic non-redox reactions (Wiesli et al, 2004;Wiedehold et al, 2006;Dideriksen et al, 2008;Mikutta et al, 2009), including the ligand-exchange process involved in mackinawite (FeS m ) formation (Butler et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Fe isotope exchange between Fe(II)aq and nanoparticulate mackinawite (FeSm) during nanoparticle growth

Guilbaud

Butler

Ellam

et al. 2010

Earth and Planetary Science Letters

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“…Iron is an abundant element in nature; however, in most aqueous aerobic environments iron forms insoluble ferric hydroxide, Fe(OH) 3 . This poses a major problem for most aerobic bacteria, as ferric hydroxide has a solubility constant of 10 Ϫ39 M, therefore limiting the concentration of ferric ions to 10 Ϫ18 M at pH 7.0.…”

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confidence: 99%

Acquisition of Iron by Alkaliphilic Bacillus Species

McMillan¹,

Velasquez

Nunn

et al. 2010

Appl Environ Microbiol

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The biochemical and molecular mechanisms used by alkaliphilic bacteria to acquire iron are unknown. We demonstrate that alkaliphilic (pH > 9) Bacillus species are sensitive to artificial iron (Fe 3؉ ) chelators and produce iron-chelating molecules. These alkaliphilic siderophores contain catechol and hydroxamate moieties, and their synthesis is stimulated by manganese(II) salts and suppressed by FeCl 3 addition. Purification and mass spectrometric characterization of the siderophore produced by Caldalkalibacillus thermarum failed to identify any matches to previously observed fragmentation spectra of known siderophores, suggesting a novel structure.

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Fe isotopic fractionation during mineral dissolution with and without bacteria

Cited by 231 publications

References 47 publications

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

Fe isotope exchange between Fe(II)aq and nanoparticulate mackinawite (FeSm) during nanoparticle growth

Acquisition of Iron by Alkaliphilic Bacillus Species

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