Near-field iron and carbon chemistry of non-buoyant hydrothermal plume particles, Southern East Pacific Rise 15°S

Hoffman, Colleen L.; Nicholas, Sarah; Ohnemus, Daniel C.; Fitzsimmons, Jessica N.; Sherrell, Robert M.; German, Christopher R.; Heller, Maija; Lee, Jong-mi; Lam, Phoebe J.; Toner, Brandy M.

doi:10.1016/j.marchem.2018.01.011

Cited by 30 publications

(35 citation statements)

References 105 publications

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“…The data on the particles we have collected suggests that most of the pFe in the plume is in the form of Fe oxyhydroxides. It is also possible that there is Fe adsorbed to the surface of POC (Toner et al, 2009;Hoffman et al, 2018) and/or mineral particles that was present but undetected by our methods. Fe oxyhydroxides will be stable in oxygenated seawater and unlikely to undergo dissolution unless this process is ligand mediated.…”

Section: Hydrothermal Plume Particle Compositionmentioning

confidence: 95%

“…However, the exact mineralogy of these particles cannot be determined due to the uncertainty of EDX analysis for elements as light as oxygen (Goldstein et al, 2003). Due to the time-scales over which plume dilution occurs it is unlikely that more structured Fe oxides such as hematite or goethite will form and Fe oxyhydroxides have been shown to be the most prevailing Fe oxide phase in hydrothermal plumes (Feely et al, 1994;Fitzsimmons et al, 2017;Lough et al, 2017;Hoffman et al, 2018).…”

Section: Mineralogy and Oxidation State Of Plume Particles By Scanninmentioning

confidence: 99%

“…Synchrotron X-ray micro-fluorescence (µXRF) was used to assess the distribution of Fe, C, and O in samples with PyMCA software used to create element maps (Solé et al, 2007). Given that hydrothermal plumes typically have a deficit of particulate inorganic carbon (PIC) and elevated concentrations of particulate organic carbon (POC) compared to seawater (Hoffman et al, 2018) we assume that the majority of carbon in our samples detected by µXRF is most likely to be organic in nature and not carbonate minerals unless the carbon map appears to be the same as the oxygen map.…”

Section: Mineralogy and Oxidation State Of Plume Particles By Scanninmentioning

confidence: 99%

“…After removing the previous two explanations for increasing proportions of sFe and cFe in the VDVF plume we are left with the possibility of transfer of Fe from the particulate fraction to the soluble and colloidal fractions. This would require the breakdown of either Fe bearing POC (Toner et al, 2009;Hoffman et al, 2018) matrices or dissolution of authigenic hydrothermal Fe minerals (Feely et al, 1987; Figure 7). The data on the particles we have collected suggests that most of the pFe in the plume is in the form of Fe oxyhydroxides.…”

Section: Hydrothermal Plume Particle Compositionmentioning

confidence: 99%

See 3 more Smart Citations

Diffuse Hydrothermal Venting: A Hidden Source of Iron to the Oceans

et al. 2019

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Section: Hydrothermal Plume Particle Compositionmentioning

confidence: 95%

Section: Mineralogy and Oxidation State Of Plume Particles By Scanninmentioning

confidence: 99%

Section: Mineralogy and Oxidation State Of Plume Particles By Scanninmentioning

confidence: 99%

Section: Hydrothermal Plume Particle Compositionmentioning

confidence: 99%

See 2 more Smart Citations

Diffuse Hydrothermal Venting: A Hidden Source of Iron to the Oceans

et al. 2019

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“…Moreover, organically complexed Fe (II) in the dissolved fraction can allow Fe (II) in the hydrothermal plumes to spread away from the vents (Hopkinson & Barbeau, 2007;Sedwick et al, 2015). There has been no report of the Fe (II) ligands, while nonsulfide Fe (II) associated with organic matrix has been found in plume particles (Hoffman et al, 2018;Toner et al, 2009Toner et al, , 2012.…”

Section: The Hydrothermally Sourced Fe Stabilized By the Dissolved Smentioning

confidence: 99%

The Size Fractionation and Speciation of Iron in the Longqi Hydrothermal Plumes on the Southwest Indian Ridge

et al. 2019

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The distribution and composition of Fe in hydrothermal plumes are crucial for understanding the contribution of hydrothermal venting to the oceanic Fe inventory. In this study, we conduct the first complete investigation of the size fractions of Fe and Fe‐binding ligands in the Longqi hydrothermal plumes on the Southwest Indian Ridge, combining the approaches of the size partitioning and reverse titration‐competitive ligand exchange‐adsorptive cathodic stripping voltammetry. Concentrations of all the Fe fractions were very high in the plume samples, and dissolved Fe (<0.2 μm) constituted a significant portion (48.7 ± 7.9%) of total Fe, which might be related to the existence of colloidal Fe oxyhydroxides and sulfides, as well as organic Fe complexes. Dissolved Fe consisted of colloidal Fe (10 kDa to 0.2 μm, ~70.2%) and soluble Fe (<10 kDa, ~29.8%). Colloidal Fe mainly contained Fe oxyhydroxides and sulfides (86.4 ± 6.2%), while most of the soluble Fe were organic Fe complexes (65.7 ± 5.4%). Fe speciation analyses showed that dissolved ligand concentrations were high in the hydrothermal plumes but were significantly lower than the dissolved Fe concentrations. Inferring from previous studies in the Longqi hydrothermal field, the ligands were most likely derived from the diffuse flow adjacent to the hydrothermal vents. The conditional stability constants (logK′FeL) of dissolved FeL (20.4 ± 0.5) were slightly higher than those of soluble FeL (19.6 ± 0.4), although they were not statistically different. Based on the ligands' size partitioning, the soluble ligands stabilized ~8.8 ± 3.8% of the hydrothermal Fe, which is over 2 times that of the colloidal ligands, ~4.0 ± 1.8%.

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Impacts of deep‐sea mining on microbial ecosystem services

Orcutt

Bradley

Brazelton

et al. 2020

Limnology & Oceanography

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Interest in extracting mineral resources from the seafloor through deep-sea mining has accelerated in the past decade, driven by consumer demand for various metals like zinc, cobalt, and rare earth elements. While there are ongoing studies evaluating potential environmental impacts of deep-sea mining activities, these focus primarily on impacts to animal biodiversity. The microscopic spectrum of seafloor life and the services that this life provides in the deep sea are rarely considered explicitly. In April 2018, scientists met to define the microbial ecosystem services that should be considered when assessing potential impacts of deep-sea mining, and to provide recommendations for how to evaluate and safeguard these services. Here, we indicate that the potential impacts of mining on microbial ecosystem services in the deep sea vary substantially, from minimal expected impact to loss of services that cannot be remedied by protected area offsets. For example, we (1) describe potential major losses of microbial ecosystem services at active hydrothermal vent habitats impacted by mining, (2) speculate that there could be major ecosystem service degradation at inactive massive sulfide deposits without extensive mitigation efforts, (3) suggest minor impacts to carbon sequestration within manganese nodule fields coupled with potentially important impacts to primary production capacity, and (4) surmise that assessment of impacts to microbial ecosystem services at seamounts with ferromanganese crusts is too poorly understood to be definitive. We conclude by recommending that baseline assessments of microbial diversity, biomass, and, importantly, biogeochemical function need to be considered in environmental impact assessments of deep-sea mining.With increasing demand for rare and critical metals-such as cobalt, copper, manganese, tellurium, and zinc-there is increasing interest in mining these resources from the seafloor (Hein et al. 2013; Wedding et al. 2015;Thompson et al. 2018). The primary mineral resources in the deep sea that attract attention fall into four categories (Figs. 1, 2): (1) massive sulfide deposits created at active high-temperature hydrothermal vent systems along mid-ocean ridges, back-arc spreading centers, and volcanic arcs, from the mixing of mineral-rich, advecting hydrothermal fluids with bottom seawater; (2) similar deposits at inactive hydrothermal vent sites, where fluid advection has ceased but mineral deposits remain; (3) polymetallic nodules that form on the seafloor of the open ocean

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Near-field iron and carbon chemistry of non-buoyant hydrothermal plume particles, Southern East Pacific Rise 15°S

Cited by 30 publications

References 105 publications

Diffuse Hydrothermal Venting: A Hidden Source of Iron to the Oceans

Diffuse Hydrothermal Venting: A Hidden Source of Iron to the Oceans

The Size Fractionation and Speciation of Iron in the Longqi Hydrothermal Plumes on the Southwest Indian Ridge

Impacts of deep‐sea mining on microbial ecosystem services

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