Organic matter effect on Fe(II) oxidation kinetics in the Labrador Sea

Santana-González, Carolina; González‐Dávila, Melchor; Santana‐Casiano, J. Magdalena; Гладышев, С. В.; Sokov, A. V.

doi:10.1016/j.chemgeo.2018.12.019

Cited by 9 publications

(11 citation statements)

References 78 publications

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“…8 and 9) that the presence of both colloidal particles and dissolved organic matter increases the half-life of Fe(II) (decreased k'). This agrees with previous work showing a decrease in the Fe(II) oxidation rate constants in seawater in the presence of some natural organic compounds (Santana-González et al, 2019). However, organic matter can have a positive or negative effect on the oxidation rate constants of Fe(II) depending on the type of organic matter and its degree of remineralization (Rose and Waite, 21 2003).…”

Section: Derived Oxidation Rate Constants As a Function Of Ph And Temperaturesupporting

confidence: 92%

“…However, organic matter can have a positive or negative effect on the oxidation rate constants of Fe(II) depending on the type of organic matter and its degree of remineralization (Rose and Waite, 21 2003). The variability in the effect of total organic carbon on Fe(II) oxidation proves that total organic carbon cannot be used as a variable in an equation describing k´ (Santana-Casiano et al, 2000;Santana-González et al, 2018;Santana-González et al, 2019). In this sense, a more detailed characterization of organic matter would be necessary, especially in a hydrothermal environment.…”

Section: Derived Oxidation Rate Constants As a Function Of Ph And Temperaturementioning

confidence: 99%

“…4), it was compared to three existing equations. The chosen equations were the first derived equation(Millero et al, 1987), the equation bySantana-Casiano et al (2005), and a recent equation using Labrador Seawater(Santana-González et al, 2019). The four equations were compared to the measured oxidation rate constants at in situ pH and T conditions.…”

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confidence: 99%

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Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

González-Santana

González‐Dávila

Lohan

et al. 2021

Geochimica et Cosmochimica Acta

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One of the recently recognized main sources of iron to the deep ocean inventory is the hydrothermal activity associated with mid-ocean ridges. Little is known about the oxidation 2 kinetics of iron(II) within these environments, especially the dependence on physicochemical parameters such as temperature (T), pH, particle size-fractionation and the effect of organic matter.Following sample collection during the GA13 section cruise, the iron(II) oxidation at six hydrothermal vent sites (Menez Gwen, Lucky Strike, Rainbow, Lost City, Broken Spur and TAG) along the Mid-Atlantic Ridge were investigated, revealing high variability. The Fe(II) oxidation rate constant analysis from multiple stations at two sites (Rainbow and TAG), revealed that factors, other than T and pH, controlled the oxidation process. Experiments on the effect of particle size-fractionation and organic matter at different pH showed that the presence of organic ligands and colloidal size particles delayed the oxidation process, while not affecting the overall pH dependency.Extending our analysis to the broader relationship between the Fe(II) oxidation rate constants across a range of temperatures (between 2 and 25 ºC) and pH (between 7 and 8) on a set of selected hydrothermal samples allowed us to derive a multiparametric equation to model the iron(II) oxidation rate constants in the ocean. This equation covers a larger range of temperatures than previous published equations, improving its applicability for global biogeochemical models.

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Section: Derived Oxidation Rate Constants As a Function Of Ph And Temperaturesupporting

confidence: 92%

Section: Derived Oxidation Rate Constants As a Function Of Ph And Temperaturementioning

confidence: 99%

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Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

González-Santana

González‐Dávila

Lohan

et al. 2021

Geochimica et Cosmochimica Acta

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“…The oxidation kinetic experiments were carried out in a 60 mL LDPE container within a double-wall glass thermo-regulated cell, connected to a thermostatic bath (Julabo), as described in previous studies. , For each oxidation kinetic study, 25 mL of the seawater sample was used. The initial concentration of added Fe(II) was 0.97 nM.…”

Section: Methodsmentioning

confidence: 99%

“…The concentration of total dissolved Fe(II), TdFe(II), in the samples for the kinetics experiments, was determined using the flow injection analysis by chemiluminescence (FIA-CL) technique with a FeLume system (Waterville Analytical) as described in previous studies. , The FIA-CL technique uses luminol as the reagent. 5 L of the luminol reagent was prepared using 2.71 × 10 –4 M of 5-amino-2,3-dihydro-1,4-phthalazinedione (Sigma), 4.93 × 10 –2 M of Na 2 CO 3 (Sigma-Aldrich), and 0.4 M of previously distilled 25% NH 3 (Panreac).…”

Section: Methodsmentioning

confidence: 99%

Exploring the Effects of Organic Matter Characteristics on Fe(II) Oxidation Kinetics in Coastal Seawater

Santana-Casiano

González-Santana

Devresse

et al. 2022

Environ. Sci. Technol.

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The iron(II) oxidation kinetic process was studied at 25 stations in coastal seawater of the Macaronesia region (9 around Cape Verde, 11 around the Canary Islands, and 5 around Madeira). In a physicochemical context, experiments were carried out to study the pseudo-first-order oxidation rate constant (k′, min–1) over a range of pH (7.8, 7.9, 8.0, and 8.1) and temperature (10, 15, 20, and 25 °C). Deviations from the calculated k cal ′ at the same T, pH, and S were observed for most of the stations. The measured t 1/2 (ln 2/k′, min) values at the 25 stations ranged from 1.82 to 3.47 min (mean 1.93 ± 0.76 min) and for all but two stations were lower than the calculated t 1/2 of 3.21 ± 0.2 min. In a biogeochemical context, nutrients and variables associated with the organic matter spectral properties (CDOM and FDOM) were analyzed to explain the observed deviations. The application of a multilinear regression model indicated that k′ can be described (R = 0.921 and SEE = 0.064 for pH = 8 and T = 25 °C) from a linear combination of three organic variables, k′OM = k cal ′ −0.11* TDN + 29.9*b DOM + 33.4*C1humic, where TDN is the total dissolved nitrogen, b DOM is the spectral peak obtained from colored dissolved organic matter (DOM) analysis when protein-like or tyrosine-like components are present, and C1humic is the component associated with humic-like compounds obtained from the parallel factor analysis of the fluorescent DOM. Results show that compounds with N in their structures mainly explain the observed k′ increase for most of the samples, although other components could also play a relevant role. Experimentally, k′ provides the net result between the compounds that accelerate the process and those that slow it down.

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A decade of progress in understanding cycles of trace elements and their isotopes in the oceans

et al. 2021

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Organic matter effect on Fe(II) oxidation kinetics in the Labrador Sea

Cited by 9 publications

References 78 publications

Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

Exploring the Effects of Organic Matter Characteristics on Fe(II) Oxidation Kinetics in Coastal Seawater

A decade of progress in understanding cycles of trace elements and their isotopes in the oceans

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