Reactivity of Inorganic Mn and Mn Desferrioxamine B with O2, O2–, and H2O2in Seawater

Wuttig, Kathrin; Heller, Maija; Croot, Peter

doi:10.1021/es4016603

Cited by 24 publications

(43 citation statements)

References 86 publications

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“…The outstanding agreement between our SRC and that of Wuttig et al (2013) should not be surprising, despite the distinct disagreement between our measured Mg-DFOB and Ca-DFOB stability constants and those of Farkas et al (1999). Remember that this disagreement is not the result of bad titration data, but of an incorrect speciation model used to interpret these data.…”

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 47%

“…Again, this is ostensibly due to regression of the data with an incorrect speciation model, not to poor quality of the data itself. Wuttig et al (2013) used the speciations of Farkas et al (1999), appropriate for 0.2 M KCl, to calculate the SRC of DFOB in seawater, obtaining log α DFB = 6.25. While the authors presented the data on which the calculation is based (Farkas et al, 1999), they provided no additional information, yet α DFB appears to be the ratio of the total ligand and the fully deprotonated free-ligand concentrations, L T /[L 3− ].…”

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

“…This choice was evidently inspired by the equilibrium constants of Farkas et al (1999), which are all expressed in terms of L 3− . The calculation of Wuttig et al (2013) is reproduced in detail in the third column of Table 9. Each line represents a DFOB solution species, X, which include L 3− and the four protonated forms, as well as the complexes with Mg considered by Farkas et al (1999) Table 9 as α L ).…”

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

“…Nevertheless, the agreement is somewhat fortuitous for several reasons. First, it seems that Wuttig et al (2013) used total rather than free concentrations of Mg and Ca, which are about 89% of total concentrations in seawater (Byrne, 2002), primarily as a result of sulfate complexation. Second, Wuttig et al (2013) (Byrne, 2002).…”

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

“…Such comparisons are only meaningful if stability constants measured in non-coordinating media can be adjusted to seawater conditions by correction with a suitable side-reaction coefficient (SRC). Wuttig et al (2013) calculated the SRC of DFOB in seawater as log α DFB = 6.25, yielding a "free DFOB" fraction of the order 10 −6 , which would effectively make it a very weak ligand. While the authors provide no details of the calculation, their SRC is ostensibly expressed in terms of fully deprotonated DFOB, a species that is virtually nonexistent in seawater and does not form any complex with most metals.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Schijf

Burns

2016

Front. Mar. Sci.

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Electrochemical techniques like adsorptive cathodic stripping voltammetry with competitive ligand equilibration (ACSV-CLE) can determine total concentrations of marine organic ligands and their conditional binding constants for specific metals, but cannot identify them. Individual organic ligands, isolated from microbial cultures or biosynthesized through genomics, can be structurally characterized via NMR and tandem MS analysis, but this is tedious and time-consuming. A complementary approach is to compare known properties of natural ligands, particularly their conditional binding constants, with those of model organic ligands, measured under suitable conditions. Such comparisons cannot be meaningfully interpreted unless the side-reaction coefficient (SRC) of the model ligand in seawater is thoroughly evaluated. We conducted series of potentiometric titrations, in non-coordinating medium at seawater ionic strength (0.7 M NaClO 4 ) over a range of metal:ligand molar ratios, to study complexation of the siderophore desferrioxamine B (DFOB) with Mg and Ca, for which it has the highest affinity among the major seasalt cations. From similar titrations of acetohydroxamic acid in the absence and presence of methanesulfonate (mesylate), it was determined that Mg and Ca binding to this common DFOB counter-ion is not strong enough to interfere with the DFOB titrations. Stability constants were measured for all DFOB complexes with Mg and Ca including, for the first time, the bidentate complexes. No evidence was found for Mg and Ca coordination with the DFOB terminal amine. From the improved DFOB speciation, we calculated five SRCs for each of the five (de)protonated forms of DFOB in trace-metal-free seawater, yet we also present a more convenient definition of a single SRC that allows adjustment of all DFOB stability constants to seawater conditions, no matter which of these forms is selected as the "component" (reference species). An example of Cd speciation in seawater containing DFOB illustrates the non-trivial use of different SRCs for polyprotic, polydentate organic ligands.

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Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 47%

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Schijf

Burns

2016

Front. Mar. Sci.

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Extracellular superoxide production by key microbes in the global ocean

Sutherland

Coe

Gast

et al. 2019

Limnology & Oceanography

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Bacteria and eukaryotes produce the reactive oxygen species superoxide both within and outside the cell. Although superoxide is typically associated with the detrimental and sometimes fatal effects of oxidative stress, it has also been shown to be involved in a range of essential biochemical processes, including cell signaling, growth, differentiation, and defense. Light‐independent extracellular superoxide production has been shown to be widespread among many marine heterotrophs and phytoplankton, but the extent to which this trait is relevant to marine microbial physiology and ecology throughout the global ocean is unknown. Here, we investigate the dark extracellular superoxide production of five groups of organisms that are geographically widespread and represent some of the most abundant organisms in the global ocean. These include Prochlorococcus, Synechococcus, Pelagibacter, Phaeocystis, and Geminigera. Cell‐normalized net extracellular superoxide production rates ranged seven orders of magnitude, from undetectable to 14,830 amol cell−1 h−1, with the cyanobacterium Prochlorococcus being the lowest producer and the cryptophyte Geminigera being the most prolific producer. Extracellular superoxide production exhibited a strong inverse relationship with cell number, pointing to a potential role in cell signaling. We demonstrate that rapid, cell‐number–dependent changes in the net superoxide production rate by Synechococcus and Pelagibacter arose primarily from changes in gross production of extracellular superoxide, not decay. These results expand the relevance of dark extracellular superoxide production to key marine microbes of the global ocean, suggesting that superoxide production in marine waters is regulated by a diverse suite of marine organisms in both dark and sunlit waters.

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Manganese biogeochemistry in the Southern Ocean, from Tasmania to Antarctica

Latour

Wuttig

Merwe

et al. 2021

Limnology & Oceanography

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Manganese (Mn) is an abundant element in the Earth's crust. However, its concentrations in open ocean seawater are low, where external inputs are scarce. In this study, we report the dissolved Mn and particulate Mn distributions in the Southern Ocean, measured along the GEOTRACES—SR3 transect, from Tasmania (Australia) to Antarctica in the Southern Ocean, during the austral summer 2018. Both dissolved Mn and particulate Mn concentrations were generally low away from localized sources (< 0.3 nmol L−1 and < 0.1 nmol L−1, respectively) along the transect. Our observations of a lower labile particulate fraction than previously measured suggest the Southern Ocean has a unique particulate Mn composition. Low surface dissolved Mn concentrations were attributed to biological uptake and few external sources. Our results suggest biological control of the Mn cycle was higher above the Antarctic continental slope, compared to the rest of the section, and our particulate Mn : P ratios indicated the presence of iron‐stressed diatoms south of the Sub‐Antarctic Front. We suggest low dissolved Mn surface concentrations may (co‐)limit phytoplankton growth in this region. Localized higher dissolved Mn concentrations were observed due to external sources, such as sedimentary and hydrothermal inputs. The presence of an eddy at the same latitude as a hydrothermal plume induced an upwelling of hydrothermally enriched waters up to 1000 m; however, no dissolved Mn inputs to the surface waters were observed. We suggest previous dissolved Mn inputs to the surface layer may be obscured by biological uptake.

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Reactivity of Inorganic Mn and Mn Desferrioxamine B with O₂, O₂^–, and H₂O₂in Seawater

Cited by 24 publications

References 86 publications

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Extracellular superoxide production by key microbes in the global ocean

Manganese biogeochemistry in the Southern Ocean, from Tasmania to Antarctica

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