Kinetics of manganese adsorption, desorption, and oxidation in coastal marine sediments

Richard, Dominique; Sundby, Bjørn; Mucci, Alfonso

doi:10.4319/lo.2013.58.3.0987

Cited by 23 publications

(11 citation statements)

References 36 publications

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“…We propose that Mn(II) diffusing up from the sediment anoxic zone is responsible for the Mn(III)-L production in the suboxic porewaters, and that these complexes may be recycled to Mn(II) upon burial or oxidized to MnO x in the oxic zone. Upward diffusion of porewater Mn(II) and/or advection of Mn(II)-bearing particles by bioturbation (Richard et al, 2013) Duckworth and Sposito, 2005;Parker et al, 2007). In the St. Lawrence Estuary, particle concentrations are greater in surface waters (2.5 -2.7 mg L -1 ) than in bottom waters (1.2 -1.5 mg L -1 ; Bourgoin and Tremblay, 2010), and we predict that surface-catalyzed oxidation (eq.1) is not the dominant oxidizing mechanism at this site, particularly as our highest MnO x concentrations were measured in bottom water samples.…”

Section: Resultsmentioning

confidence: 99%

“…The rate of Mn (II) oxidation is a function of the flux of dMn T out of the sediments, the nature of the ligand(s) in the water column, the abundance of particles in the water column, and the dO 2 . Mn(II) escapes from the sediments to the overlying waters at both study sites, and the appearance of Mn oxides and Mn(III)-L in bottom waters is clear evidence of Mn(II) oxidation in the water column (Sundby et al, 1981;Richard et al, 2013). (Yeats et al, 1979) Table Recovery tests of dMn T measured using a 100-cm cell coupled to a UV/Vis spectrophotometer following a heating step.…”

Section: Discussionmentioning

confidence: 99%

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Soluble Mn(III)–L complexes are abundant in oxygenated waters and stabilized by humic ligands

Oldham

Mucci

Tebo

et al. 2017

Geochimica et Cosmochimica Acta

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145

112

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Dissolved Mn (dMn T) is thought to be dominated by metastable Mn(II) in the presence of oxygen, as the stable form is insoluble Mn(IV). We show, for the first time, that Mn(III) is also stable as a soluble species in the oxygenated water column, when stabilized by organic ligands as Mn(III)-L complexes. We measured Mn(III)-L complexes in the oxygenated waters of a coastal fjord and a hemipelagic system where they make up to 86 % of the dMn T. Although Mn(III) forms similar complexes to Fe(III), unlike most of the analogous Fe(III)-L complexes, the Mn(III)-L complexes are not colloidal, as they pass through both 0.20 µm and 0.02 µm filters. Depending on the kinetic stability of the Mn(III) complexes and the microbial community of a given system, these Mn(III)-L complexes are capable of donating or accepting electrons and may therefore serve as both reductants or oxidants, can be biologically available, and can thus participate in a multitude of redox reactions and biogeochemical processes. Furthermore, sample acidification experiments revealed that Mn(III) binding to humic ligands is responsible for up to 100 % of this complexation, which can influence the formation of other metal complexes including Fe(III) and thus impact nutrient availability and uptake. Hence, humic ligands may play a greater role in dissolved Mn transport from coastal areas to the ocean than previously thought. 1.0 Introduction: Manganese (Mn) is ubiquitous in the global ocean, where it is an essential trace nutrient in the electron transfer processes of several metallo-enzymes-notably in photosystem II for photosynthetic organisms. In its solid oxidized form, it serves as an electron acceptor in the bacterial decomposition of sedimentary organic matter and acts as an important scavenger for 1 many trace elements and radionuclides. The chemical speciation of Mn in marine systems governs its diverse functions and is ultimately controlled by the redox conditions of the environment and the microbial community. The favorable oxidation state of Mn in oxic waters is Mn(IV), and thus Mn in oxygenated waters is primarily bound to oxygen as solid Mn(III/IV)oxides (MnO x). However, soluble Mn(II) is metastable in oxygenated waters because the oxidation of Mn(H 2 O) 6 2+ to MnO x by O 2 in an one electron transfer is thermodynamically unfavorable and the two electron transfer is kinetically slow (Luther 2010), unless facilitated by microbes, surface catalysis or superoxide-promotion (Stumm and Morgan, 1996). In the last decade, soluble manganese (dMn T) speciation has been re-evaluated to include soluble Mn(III) bound to ligands (Mn(III)-L complexes) in low oxygen environments. Mn(III)-L complexes have been measured in the suboxic porewaters of the St. Lawrence Estuary (Madison et al., 2013), the suboxic waters of the Black Sea (Yakushev et al., 2007, 2009; Trouwborst et al., 2006) and the Baltic Sea (Dellwig et al., 2012) as well as the anoxic bottom waters of the Chesapeake Bay (Trouwborst et al., 2006; Oldham et al., 2015). Because Mn(III)-L complexe...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Soluble Mn(III)–L complexes are abundant in oxygenated waters and stabilized by humic ligands

Oldham

Mucci

Tebo

et al. 2017

Geochimica et Cosmochimica Acta

Self Cite

145

112

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“…Dissolved oxygen levels were above 5 mg/l throughout the year, indicating that a hypoxic event was not the source of elevated Mn at Copano East in January. Many other studies have found high spatial (Statham et al 2005) and temporal (Shiller 1997;Elsdon and Gillanders 2006) variation in dissolved Mn, which is not unexpected since Mn behavior is highly influenced by natural redox cycles and mediated by microbial activities (Thamdrup et al 1994;Pakhomova et al 2007;Richard et al 2013). …”

Section: Temporal Patternsmentioning

confidence: 89%

Spatiotemporal Variation of Trace Elements and Stable Isotopes in Subtropical Estuaries: II. Regional, Local, and Seasonal Salinity-Element Relationships

Mohan

Walther

2014

Estuaries and Coasts

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Trace elements and stable isotopes are commonly used in chronologically formed biominerals as proxies of temperature and/or salinity in estuarine and marine environments. To accurately use the chemistry of biominerals as salinity proxies, understanding the consistency of dissolved element-salinity relationships across spatiotemporal scales is essential. We examined relationships between dissolved Ba:Ca, Sr:Ca, Mg:Ca, Mn:Ca, δ 18 O, and salinity on regional, local, and seasonal scales in the lower portions of subtropical estuaries (salinities 15-42 ppt) of Texas, including locations where seasonal alternations between negative and positive estuaries can occur. Across all spatiotemporal scales, Ba:Ca displayed a negative linear relationship within the sampled salinity range and was elevated at sites furthest from the ocean and lowest at locations closest to the Gulf of Mexico. This pattern remained consistent as the neutral estuary switched from negative to positive after a rain event. On regional scales, δ 18 O displayed a positive linear relationship with salinity and was strongly related to evaporation rates. On local and seasonal scales, evaporation-enriched δ 18 O at upper enclosed estuarine sites and this pattern was consistent over time including periods of reverse estuary conditions. Dissolved Sr:Ca and Mg:Ca varied linearly with salinity on regional scales but displayed minimal variation across temporal scales within an estuary. High variability in dissolved Mn:Ca-salinity relations was found at all spatiotemporal scales, with localized episodic peaks of Mn:Ca possibly due to sediment disturbance. Although dissolved Ba:Ca and δ 18 O were not predictably related to salinity on local scales, consistent up-estuary enrichment and lowerestuary depletion make these two constituents reliable proxies for animal movements across the ocean-estuary gradient as recorded in chronologically formed biominerals.

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“…Mn-oxides altered pyrite, contributing to the initial precipitation of Co-and Mn-rich deposits. The latter reaction may lead to a diffusion of Mn in the sediments, which would explain the distribution of Mn around the appendages of the analyzed marrellomorph (Richard et al, 2013;Fig. 13).…”

Section: Late Diagenesis Metamorphism and Modern Weatheringmentioning

confidence: 99%

Taphonomic pathway of exceptionally preserved fossils in the Lower Ordovician of Morocco

Saleh

Pittet

Sansjofre

et al. 2020

Geobios

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Kinetics of manganese adsorption, desorption, and oxidation in coastal marine sediments

Cited by 23 publications

References 36 publications

Soluble Mn(III)–L complexes are abundant in oxygenated waters and stabilized by humic ligands

Soluble Mn(III)–L complexes are abundant in oxygenated waters and stabilized by humic ligands

Spatiotemporal Variation of Trace Elements and Stable Isotopes in Subtropical Estuaries: II. Regional, Local, and Seasonal Salinity-Element Relationships

Taphonomic pathway of exceptionally preserved fossils in the Lower Ordovician of Morocco

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