Metal flux from hydrothermal vents increased by organic complexation

Sander, Sylvia G.; Koschinsky, Andrea

doi:10.1038/ngeo1088

Cited by 284 publications

(208 citation statements)

References 45 publications

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“…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. Potentially a more ubiquitous pathway, recent studies have shown that organic ligands bind 4-8% of the dissolved Fe in hydrothermal plumes (42)(43)(44). This organic chelation protects the Fe from precipitation and stabilizes it in the dissolved phase as it is advected away from the vent site.…”

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.

150

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.

150

125

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“…Binding of Fe to small organic complexes can explain a higher solubility than expected for inorganic suspension alone (Sander and Koschinsky, 2011;Toner et al, 2009;Bennett et al, 2008;Kuma et al, 1996), where b 100 nm fractions of iron were lower (Table 2B). However, although no DOC data are available for our sample sites, the concentrations of organic matter at site D, where the b100 nm fraction of iron was the highest, is not expected to be higher than at site B and the control site, where b 100 nm fractions of iron were lower (Table 2B).…”

Section: Discussionmentioning

confidence: 99%

“…Steep pH gradients combined with metal enriched fluid emissions typical at these high temperature deep sea hydrothermal vents (Kadar et al, 2005) are conditions known to facilitate the formation of Fe-rich nanoparticles (NPs) (Kennedy et al, 2004;Kim et al, 2008;Yucel et al, 2011;Wu et al, 2011). Recent research suggests that an unknown fraction of this flux escapes from precipitation/flocculation reactions partly due to stabilisation by organic ligands (Sander and Koschinsky, 2011;Toner et al, 2009;Bennett et al, 2008), and due to nanoparticles reported to be kinetically stable (Yucel et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Metallic nanoparticle enrichment at low temperature, shallow CO2 seeps in Southern Italy

et al. 2012

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a b s t r a c t a r t i c l e i n f oWe report on metal enrichment along a natural pH gradient owing to increased CO 2 degassing at cold, shallow seeps of Vulcano Island in the Mediterranean Sea, off Sicily. We assessed composition of unfiltered and filtered seawater (b100 nm) along acidic zones ranging between ambient and pH 5, and showed that most seep derived elements are present as nanoclusters which then aggregate into larger colloids while mixing with ambient seawater along a pH gradient. Size and elemental composition of such naturally occurring nanoparticles assessed by modern characterisation methods were in good agreement with the results from conventional analytical methods. We provide analytical evidence for the presence in the water column of a large fraction of seep derived elements (e.g. approximately 50% of iron, over 80% of Mn, 100% of Cr, S and Zn) in the form of nano sized particles (e.g. b 100 nm) even at typical open ocean pHs. We launch in situ sampling protocols and sample preparation procedures for multi-method suitable to obtain accurate measurements on nanoparticles from environmental samples. Based on our results a first insight to the formation of natural nanoparticles at cold CO 2 seeps is presented and the persistence of such nano-clusters in the surrounding seawater is stipulated.

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“…Other sources are sediments (Bordovsky, 1957), dust (Paris and Desboeufs, 2013, Figure 2A). To date, the characterization of organic ligands associated with hydrothermal vents, a terrestrial input, is in its infancy but will be highly relevant for upwelling regions (e.g., Sander and Koschinsky, 2011;Kleint et al, 2016); their potential contribution to any of the three groups of ligands considered is not yet known. In addition, rain contains humics but also malonic, citric, and oxalic acids that stabilize iron in solution (Willey et al, 2000) as well as iron binding ligands detected by electrochemistry (Cheize et al, 2012; Table 1).…”

Section: Humicsmentioning

confidence: 99%

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

2017

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Iron-binding ligands are paramount to understanding iron biogeochemistry and its potential to set the productivity and the magnitude of the biological pump in >30% of the ocean. However, the nature of these ligands is largely uncharacterized and little is known about their sources, sensitivity to photochemistry and biological transformation, or scavenging behavior. Despite many uncertainties, there is no doubt that ligands are produced by a wide range of biotic and abiotic processes, and that the bulk ligand pool encompasses a diverse range of molecules. Despite widespread recognition of the likelihood of a continuum of ligand classes making up the bulk ligand pool, studies to date largely focused on the dominant ligand. Thus, most studies have overlooked the need to assess where these targeted molecules fit across the spectrum of ligands that comprise the bulk ligand pool. Here we summarize present knowledge to critically assess the source(s), function(s), production pathways, and loss mechanisms of three important iron-binding organic ligand groups in order to assess their distinctive characteristics and how they link with observed ligand distributions. We considered that ligands are contained in broad groupings of exopolymer substances (EPS), humic substances (HS), and siderophores; using literature data for speciation modeling suggested that this adequately described the iron speciation reported in the ocean. We hypothesize that a holistic viewpoint of the multi-faceted controls on ligands dynamics is essential to begin to understand why some ligands can be expected to dominate in particular oceanic regions, depth strata, or exhibit seasonality and/or lateral gradients. We advocate that the development of a regional classification will enhance our understanding of the changing composition of the bulk ligand pool across the global ocean and to help address to what extent seasonality influences the makeup of this pool. This classification, based on selected functional ligand classes, can act as a bridge to use future ligand datasets to fill in the gaps in the continuum.

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Metal flux from hydrothermal vents increased by organic complexation

Cited by 284 publications

References 45 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

Metallic nanoparticle enrichment at low temperature, shallow CO2 seeps in Southern Italy

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

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