Hydrothermal vents as a kinetically stable source of iron-sulphide-bearing nanoparticles to the ocean

Yücel, Mustafa; Gartman, Amy; Chan, Clara S.; Luther, George W.

doi:10.1038/ngeo1148

Cited by 216 publications

(175 citation statements)

References 28 publications

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“…Fe:C ratios are calculated using an AOU:C ratio of 1.6 (61) and are in units of μmol/mol. the dFe in global vent fluids (40,41). These colloids would pass through the 0.4-μm filter used to operationally define dissolved Fe in this study, and due to their small size they would sink very slowly, providing a mechanism by which inorganic dFe might be carried away from vents in the dissolved fraction.…”

Section: Resultsmentioning

confidence: 99%

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

Fitzsimmons

Boyle

Jenkins

2014

Proc. Natl. Acad. Sci. U.S.A.

147

125

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Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on recent abyssal dFe enrichments near hydrothermal vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209-212] argues that some hydrothermal Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (<0.4 μm) measurements from the abyssal southeast and southwest Pacific Ocean, where dFe of 1.0-1.5 nmol/kg near 2,000 m depth (0.4-0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be hydrothermally derived based on its correlation with primordial 3 He and dissolved Mn (dFe: 3 He of 0.9-2.7 × 10 6 ). Given the known sites of hydrothermal venting in these regions, this dFe must have been transported thousands of kilometers away from its vent site to reach our sampling stations. Additionally, changes in the size partitioning of the hydrothermal dFe between soluble (<0.02 μm) and colloidal (0.02-0.4 μm) phases with increasing distance from the vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02-1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that hydrothermal vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input).iron | hydrothermal vents | helium | East Pacific Rise | trace metals

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Section: Resultsmentioning

confidence: 99%

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

Fitzsimmons

Boyle

Jenkins

2014

Proc. Natl. Acad. Sci. U.S.A.

147

125

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“…The first emphasizes stabilization of Fe by organic ligands [15,34], the second highlights an important role of Fe-sulfur nanoparticle pyrite [35,36], while a third emphasizes the importance of colloidal Fe(III)-oxyhydroxide phases. Each mechanism will have distinct influences on the residence time and reactivity of Fe within the plume.…”

Section: Discussion (A) Evidence Of the Stabilization Of Hydrothermalmentioning

confidence: 99%

Impact of hydrothermalism on the ocean iron cycle

Tagliabue

2016

Phil. Trans. R. Soc. A.

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As the iron supplied from hydrothermalism is ultimately ventilated in the iron-limited Southern Ocean, it plays an important role in the ocean biological carbon pump. We deploy a set of focused sensitivity experiments with a state of the art global model of the ocean to examine the processes that regulate the lifetime of hydrothermal iron and the role of different ridge systems in governing the hydrothermal impact on the Southern Ocean biological carbon pump. Using GEOTRACES section data, we find that stabilization of hydrothermal iron is important in some, but not all regions. The impact on the Southern Ocean biological carbon pump is dominated by poorly explored southern ridge systems, highlighting the need for future exploration in this region. We find inter-basin differences in the isopycnal layer onto which hydrothermal Fe is supplied between the Atlantic and Pacific basins, which when combined with the inter-basin contrasts in oxidation kinetics suggests a muted influence of Atlantic ridges on the Southern Ocean biological carbon pump. Ultimately, we present a range of processes, operating at distinct scales, that must be better constrained to improve our understanding of how hydrothermalism affects the ocean cycling of iron and carbon. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.

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“…Laboratory studies have shown that a range of simple organic molecules can impact Fe(II) oxidation rates, and whilst some had no effect, others directly or indirectly slowed the net oxidation rate (Santana-Casiano et al 2000). It is also possible that inorganic complexes such as sulphides could stabilize Fe(II) in solution in the form of Fe sulphide nanoparticles (Yücel et al 2011), but evidence for this in shelf systems has not been demonstrated.…”

Section: Fe(ii) Oxidation Kinetics In Core-top and Water Column Seawatermentioning

confidence: 99%

Stability of dissolved and soluble Fe(II) in shelf sediment pore waters and release to an oxic water column

et al. 2017

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Shelf sediments underlying temperate and oxic waters of the Celtic Sea (NW European Shelf) were found to have shallow oxygen penetrations depths from late spring to late summer (2.2-5.8 mm below seafloor) with the shallowest during/after the spring-bloom (mid-April to mid-May) when the organic carbon content was highest. Sediment porewater dissolved iron (dFe,\0.15 lm) mainly ([85%) consisted of Fe(II) and gradually increased from 0.4 to 15 lM at the sediment surface to *100-170 lM at about 6 cm depth. During the late spring this Fe(II) was found to be mainly present as soluble Fe(II) ([85% sFe, \0.02 lm). Sub-surface dFe(II) maxima were enriched in light isotopes (d 56 Fe -2.0 to -1.5%), which is attributed to dissimilatory iron reduction (DIR) during the bacterial decomposition of organic matter. As porewater Fe(II) was oxidised to insoluble Fe(III) in the surface sediment layer, residual Fe(II) was further enriched in light isotopes (down to -3.0%). Ferrozine-reactive Fe(II) was found in surface porewaters and in overlying core top waters, and was highest in the late spring period. Shipboard experiments showed that depletion of bottom water Responsible Editor: Martin Solan.Electronic supplementary material The online version of this article (doi:10.1007/s10533-017-0309-x) contains supplementary material, which is available to authorized users. 49-67 DOI 10.1007/s10533-017-0309-x oxygen in late spring can lead to a substantial release of Fe(II). Reoxygenation of bottom water caused this Fe(II) to be rapidly lost from solution, but residual dFe(II) and dFe(III) remained (12 and 33 nM) after [7 h. Iron(II) oxidation experiments in core top and bottom waters also showed removal from solution but at rates up to 5-times slower than predicted from theoretical reaction kinetics. These data imply the presence of ligands capable of complexing Fe(II) and supressing oxidation. The lower oxidation rate allows more time for the diffusion of Fe(II) from the sediments into the overlying water column. Modelling indicates significant diffusive fluxes of Fe(II) (on the order of 23-31 lmol m -2 day -1 ) are possible during late spring when oxygen penetration depths are shallow, and pore water Fe(II) concentrations are highest. In the water column this stabilised Fe(II) will gradually be oxidised and become part of the dFe(III) pool. Thus oxic continental shelves can supply dFe to the water column, which is enhanced during a small period of the year after phytoplankton bloom events when organic matter is transferred to the seafloor. This input is based on conservative assumptions for solute exchange (diffusion-reaction), whereas (bio)physical advection and resuspension events are likely to accelerate these solute exchanges in shelf-seas.

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Hydrothermal vents as a kinetically stable source of iron-sulphide-bearing nanoparticles to the ocean

Cited by 216 publications

References 28 publications

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

Impact of hydrothermalism on the ocean iron cycle

Stability of dissolved and soluble Fe(II) in shelf sediment pore waters and release to an oxic water column

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