EXAFS analysis of iron cycling in mangrove sediments downstream a lateritized ultramafic watershed (Vavouto Bay, New Caledonia)

Noël, Vincent; Marchand, Cyril; Juillot, Farid; Ona-Nguéma, Georges; Viollier, Éric; Marakovic, Gregory; Olivi, Luca; Delbes, Ludovic; Gelebart, Frédéric; Morin, Guillaume

doi:10.1016/j.gca.2014.03.019

Cited by 94 publications

(92 citation statements)

References 89 publications

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“…The closer is the stand to the shore, the more intense are Fe reduction-oxidation cycles. In addition, concentrations of solid Fe phases (FeASC and FeHCl) decreased from the land-side to the sea-side of the mangrove in this study, confirming Noel et al [44] hypothesis of a Fe loss from the salt-flat to the Rhizophora stand (i.e., from the land to the shore). The loss of Fe with tides may also explain why dissolved sulfides were only detected in Rhizophora sediments.…”

Section: Distribution and Speciation Of Redox Sensitive Elements: Irosupporting

confidence: 91%

“…In addition to reduction, intense re-oxidation of aqueous Fe(II) and Fe-sulfides are suspected, and can lead to the high dissolved iron concentrations as well as to the low measured pH. Such process was detected by Noel et al [44], which results in the formation of ferrihydrite, lepidocrocite and likely goethite in Avicennia and Rhizophora sediments. In addition, these authors found that the relative proportion of a newly formed and poorly ordered iron-oxyhydroxides was higher in the Rhizophora mangrove stand, suggesting that tidal fluctuations may lead to uninterrupted Fe reduction-oxidation cycles.…”

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 96%

“…However, due to coastal current [43], some of these minerals may have been deposited in the mangrove, explaining the high concentrations of Fe measured in the solid phase. Within the salt-flat, reduced dissolved iron (Fe precipitated as ferrihydrite and lepidocrocite [44]. Presence of Fe(III) has an influence on sulfur cycling in sediments because it is involved in the oxidation of reduced free sulfide, sulphato-reduction being the main process of OM decomposition in mangroves [45,46].…”

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 99%

“…In mangroves, TS is mainly composed of pyrite whose synthesis and stabilization are favored in the most reduced sediment horizons [11]. Noel et al [44] showed that goethite, the major Fe hosts in the upward horizons of a mangrove developing downstream lateritic soils, progressively disappears with increasing depth, where Fe(II)-bearing pyrite forms, as a result of a sulfate-reduction process. In addition to reduction, intense re-oxidation of aqueous Fe(II) and Fe-sulfides are suspected, and can lead to the high dissolved iron concentrations as well as to the low measured pH.…”

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 99%

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Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

Deborde

Marchand

Molnar

et al. 2015

JMSE

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Abstract:In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ increase in: (i) water content; (ii) TOC; (iii) mangrove-derived OM; II/ and decrease in: (i) salinity; (ii) redox; (iii) pH; (iv) solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and sulfate. The loss of total Fe observed towards the sea-side may be related to sulfur oxidation and to more intense tidal flushing of dissolved components. Except the organic forms, dissolved N and P concentrations were very low OPEN ACCESSJ. Mar. Sci. Eng. 2015, 3 53beneath Avicennia and Rhizophora stands, probably as a result of their uptake by the root systems. However, in the unvegetated salt-flat, NH4 + can accumulate in organic rich and anoxic layers. This study shows: (i) the evolution of mangrove sediment biogeochemistry along the intertidal zone as a result of the different duration of tidal inundation and organic enrichment; and (ii) the strong links between the distribution and speciation of the different elements.

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Section: Distribution and Speciation Of Redox Sensitive Elements: Irosupporting

confidence: 91%

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 96%

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 99%

Section: Distribution and Speciation Of Redox Sensitive Elements: Iromentioning

confidence: 99%

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Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

Deborde

Marchand

Molnar

et al. 2015

JMSE

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“…In parallel, nickel has been recognised as an essential biocatalytic metal agent in iron-sulphur enzymes, especially acetyl-CoA synthase, which is a major enzyme of acetogenic bacteria and methanogens for fixing CO/CO 2 (Darnaud et al, 2003). Lastly, nickel has a particular ability to be incorporated in pyrite during early diagenesis of marine and coastal sediments (Huerta-Diaz and Morse, 1992;Morse and Luther, 1999;Large et al, 2017), which largely contributes to Ni immobilisation in mangroves (Noël et al, 2014(Noël et al, , 2015. The image that arises is one in which pyrite is a regulator of iron and trace metal distribution in modern and ancient environments.…”

Section: Introductionmentioning

confidence: 99%

Nickel accelerates pyrite nucleation at ambient temperature

Morin¹,

Noël²,

Menguy³

et al. 2017

Geochem. Persp. Let.

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Chemical and isotopic compositions of pyrites are used as biogeochemical tracers in Archean to modern sediments. Moreover, pyrite formation from monosulphide precursors has been proposed to be involved in prebiotic chemistry. However, the factors controlling pyrite formation and distribution in the sedimentary record are incompletely understood. Here, we show that Ni 2+ ions accelerate ~5 times the nucleation of pyrite at ambient temperature. Using Fe and Ni K-edge EXAFS and TEM-EDXS we demonstrate that Ni(II) is directly involved in the nucleation of pyrite synthesised by reacting Fe(III) with Na 2 S in the presence of aqueous Ni(II) impurity. Initial formation of a Ni-enriched pyrite core is followed by overgrowth of a Ni-depleted pyrite shell, leading to compositional zoning of the Fe 1-x Ni x S 2 nanocrystals (x = 0.05 to 0.0004). The molar Ni/Fe ratio in the final aqueous solution was then 2000 times lower than the starting ratio of 0.01. This enhanced and accelerated trapping of Ni by pyrite could be of prime importance in controlling Ni concentration in the ocean during early diagenesis of marine sediments, and could thus have important implications for interpreting abundances of Ni and pyrite in the sedimentary record. In addition, acceleration of pyrite nucleation in the presence of nickel could help understanding the role of Fe-Ni sulphides in catalysing potential prebiotic reactions.

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Soil and Aboveground Carbon Stocks in a Planted Tropical Mangrove Forest (Can Gio, Vietnam)

Vinh

Marchand

Linh

et al. 2021

Wetland Carbon and Environmental Management

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Can Gio mangrove is the largest in Vietnam, developing on approximately 35000 hectares. This forest was partially destroyed during the Vietnamese war. A restoration program was developed between the late 70s and the early 90s, using Rhizophora apiculata Blume propagules. Currently, the Can Gio mangrove forest regenerates naturally and presents a specific species zonation along the intertidal elevation gradient. Rhizophora dominates the inner forest at the highest elevation, while at an intermediate location, Rhizophora and Avicennia cohabit with other scattered species. The lowest position is colonized by Avicennia.Within this context, the main objectives of this study were to determine the soil physicochemical characteristics, as well as the quality (C/N ratios and δ 13 C) and the quantity (carbon content and stocks) of the organic matter stored beneath each mangrove stand. In addition, we were interested in determining the above-ground biomass and the total carbon stocks of the ecosystem (without considering the below-ground biomass). Carbon stocks of the Can Gio mangrove forest ranged from 150 to 479 Mg C ha -1 , with up to 86 % of the C stored in the upper meter of the soil. The inner forest has the highest stock, followed by the transitional forest, and the fringe forest. The depth extension of the root system of the current forest was estimated, and its contribution to the soil carbon stock was calculated, using the adjacent mudflat as a proxy for the antecedent stocks. Our results show that, for the last 40 years, the current mature planted Rhizophora forest stored 25.26 Mg C ha -1 . Consequently, mangrove plantation and restoration after the war was a success in terms of carbon storing.We suggest that the destruction of the Can Gio mangrove forests for urban development would induce the loss of an efficient CO2 sink.

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EXAFS analysis of iron cycling in mangrove sediments downstream a lateritized ultramafic watershed (Vavouto Bay, New Caledonia)

Cited by 94 publications

References 89 publications

Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

Nickel accelerates pyrite nucleation at ambient temperature

Soil and Aboveground Carbon Stocks in a Planted Tropical Mangrove Forest (Can Gio, Vietnam)

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