Determination of Iron Speciation by Cathodic Stripping Voltammetry in Seawater Using the Competing Ligand 2-(2-Thiazolylazo)-p-cresol (TAC)

Croot, Peter; Johansson, Mia

doi:10.1002/(sici)1521-4109(200005)12:8<565::aid-elan565>3.3.co;2-c

Cited by 64 publications

(129 citation statements)

References 25 publications

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“…However, the conditional stability (kinetics of formation and dissociation) of the amorphous Fe colloids should equal the conditional stability of the binding by organic Febinding ligands in order to exist in the presence of free strong Fe-binding ligands. An increased apparent Febinding capacity could be caused by a mixture of inorganic colloids and organic forms (Boyé et al, 2005;Croot and Johansson, 2000). The colloidal Fe(III) oxyhydroxides resulting from the Fe addition in experiment A could have formed surface-active amorphous colloids that appeared as a (saturated) strong Febinding capacity upon titration.…”

Section: Organically Complexed Ferric Ironmentioning

confidence: 98%

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Enhancement of the reactive iron pool by marine diatoms

et al. 2008

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Abstract Short term (2 days) laboratory experiments were performed to study the change in irradiance induced production of Fe(II) in seawater in the presence of two open oceanic Southern Ocean diatom species, Thalassiosira sp. and Chaetoceros brevis. Three irradiance conditions were applied: 1) UVB + UVA + VIS, 2) UVA + VIS, and 3) VIS, and Fe concentrations of 0 and 5 nM Fe were added to natural Southern Ocean seawater (containing 0.32 nM dissolved Fe and 1.69 equivalents of nM L − 1 Fe dissolved organic ligands, log K′ = 22.03). The photoproduced concentration of Fe(II) showed no relationship with the concentration of total dissolved Fe or the concentration of strongly chelated iron. During incubations with the diatoms an increase in the Fe(II) concentration during the second day suggested a modification of the Fe speciation. In the presence of Thalassiosira sp. photoreduction of Fe(III) was observed, whereas in the presence of C. brevis irradiance independent Fe(III) reduction played an important role in the Fe(II) production. Furthermore, a decrease in the strongly chelated Fe concentration, in concert with a decrease in the conditional stability constant, suggested a modification of the strongly chelated Fe fraction in the experiments with C. brevis. The chelated Fe fraction did not change in cultures with Thalassiosira sp. Overall, the presence of diatoms appeared to enhance the reactive Fe pool improving the biological availability of Fe.

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Section: Organically Complexed Ferric Ironmentioning

confidence: 98%

“…The reagent 2-(2-Thiazolylazo)-p-cresol (TAC) (Aldrich, used as received) was used as competing ligand (Croot and Johansson, 2000). All solutions were prepared using 18. and allowed to equilibrate overnight (N 15 h) with 5 mmol L − 1 borate buffer and 10 μmol L − 1 TAC.…”

Section: Cle-acsvmentioning

confidence: 99%

Enhancement of the reactive iron pool by marine diatoms

et al. 2008

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“…DOC was determined with a Shimadzu TOC analyzer and BA was determined by epifluorescence microscopy (both described by Pulido-Villena et al [2008]). [L 0 ] was determined by a competitive ligand equilibration with 2-(2-thiazolyazo-)-pcresol (TAC) followed by adsorptive cathodic stripping voltammetry (CL-ACSV) [Croot and Johansson, 2000]. [L 0 ] were calculated with the ''Van den Berg/Ruzic'' linearization method considering only one class of ligands (see auxiliary material 1 ).…”

Section: Sampling and Analysismentioning

confidence: 99%

Dust iron dissolution in seawater: Results from a one‐year time‐series in the Mediterranean Sea

Wagener¹,

Pulido-Villena²,

Guieu³

2008

Geophysical Research Letters

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[1] A better comprehension of atmospheric iron dissolution in seawater would be a key advance in understanding the atmospheric supply of iron to the ocean and its role on marine biogeochemistry. So far, different studies have demonstrated that dissolution of atmospheric iron depends on physical and chemical properties of the particles, which can be modified during their transport from the source. Here, based on a one-year time-series in the Western Mediterranean Sea, we show that dissolution of iron from a Saharan desert dust sample in seawater follows the seasonal trend of the dissolved organic carbon (DOC) variability in the surface layer. As part of the DOC pool, the role of iron binding ligands, probably derived from bacteria activity, has also been investigated. The dust iron dissolution rates are found to be linearly dependent on iron binding ligands and dissolved organic carbon concentrations (r 2 > 0.65, p < 0.01, n = 9).

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“…The overall speciation of Fe III in seawater has been found to be dominated by complexation with organic ligands (Boye et al, 2001;Croot and Johansson, 2000;Rue and Bruland, 1995;van den Berg, 1995), believed to be produced by bacteria or phytoplankton. The inorganic speciation of Fe III is strongly influenced by Fe(OH) x species (Byrne et al, 1988;Millero et al, 1995;Turner et al, 1981).…”

Section: Iron Speciation In Seawatermentioning

confidence: 99%

Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mescoscale iron enrichment

et al. 2005

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Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. concentrations increased at the depth of the chlorophyll maximum when iron concentrations returned to pre-infusion concentrations (b80 pM) possibly due to biological production related to iron reductase activity.In this work, Fe(II) and dissolved iron were used as tracers themselves for subsequent iron infusions when no further SF 6 was added. EisenEx was subject to periods of weak and strong mixing. Slow mixing after the second infusion allowed significant concentrations of Fe(II) and Fe to exist for several days. During this time, dissolved and total iron in the infusion plume behaved almost conservatively as it was trapped between a relict mixed layer and a new rain-induced mixed layer. Using dissolved iron, a value for the vertical diffusion coefficient K z =6.7F0.7 cm 2 s À1 was obtained for this 2-day period. During a subsequent surface survey of the iron-enriched patch, elevated levels of Fe(II) were found in surface waters presumably from Fe(II) dissolved in the rainwater that was falling at this time.Model results suggest that the reaction between uncomplexed Fe(III) and O 2 À was a significant source of Fe(II) during EisenEx and helped to maintain high levels of Fe(II) in the water column. This phenomenon may occur in iron enrichment experiments when two conditions are met: (i) When Fe is added to a system already saturated with regard to organic complexation and (ii) when mixing processes are slow, thereby reducing the dispersion of iron into under-saturated waters. D

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Determination of Iron Speciation by Cathodic Stripping Voltammetry in Seawater Using the Competing Ligand 2-(2-Thiazolylazo)-p-cresol (TAC)

Cited by 64 publications

References 25 publications

Enhancement of the reactive iron pool by marine diatoms

Enhancement of the reactive iron pool by marine diatoms

Dust iron dissolution in seawater: Results from a one‐year time‐series in the Mediterranean Sea

Spatial and temporal distribution of Fe(II) and H2O2 during EisenEx, an open ocean mescoscale iron enrichment

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