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Christopher R German - One of the best experts on this subject based on the ideXlab platform.
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dynamic biogeochemistry of the particulate sulfur pool in a buoyant deep sea Hydrothermal Plume
ACS Earth and Space Chemistry, 2020Co-Authors: Brandi R Cron, Christopher R German, Gregory J Dick, Cody S Sheik, Fotioschristos A Kafantaris, Gregory K Druschel, Jeffrey S Seewald, John A Breier, Brandy M. TonerAbstract:In deep-ocean Hydrothermal vent systems, oxidation–reduction (redox) reactions involving sulfur are known to fuel primary production via chemosynthesis. The particulate sulfur pool within buoyant Hydrothermal Plumes available to microorganisms as metabolic substrates remains undescribed. In this study, buoyant Hydrothermal Plume particles were collected from the Von Damm Vent Field, Mid-Cayman Rise, Caribbean. A novel in situ filtration system and remotely operated vehicle were used to collect samples along vertical profiles above two sites close to the summit of Mount Dent. Particulate sulfur speciation was measured using sulfur 1s X-ray absorption near edge structure (XANES) spectroscopy. The activity of sulfur-cycling genes in the buoyant Plume was measured using metatranscriptomic sequencing. Our results indicate that both solid-state sulfur chemistry and microbial activity within the Von Damm buoyant Plume are dynamic and diverse over short temporal and spatial scales. The particulate sulfur species ...
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near field iron and carbon chemistry of non buoyant Hydrothermal Plume particles southern east pacific rise 15 s
Marine Chemistry, 2018Co-Authors: Colleen L. Hoffman, Christopher R German, Jessica N. Fitzsimmons, Sarah L. Nicholas, Robert M. Sherrell, Maija Heller, Daniel C Ohnemus, Brandy M. TonerAbstract:Abstract Iron (Fe)-poor surface waters limit phytoplankton growth and their ability to remove carbon (C) from the atmosphere and surface ocean. Over the past few decades, research has focused on constraining the global Fe cycle and its impacts on the global C cycle. Hydrothermal vents have become a highly debated potential source of Fe to the surface ocean. Two main mechanisms for transport of Fe over long distances have been proposed: Fe-bearing nanoparticles and organic C complexation with Fe in the dissolved (dFe) and particulate (pFe) pools. However, the ubiquity and importance of these processes is unknown at present, and very few vents have been investigated for Fe-Corg interactions or the transport of such materials away from the vent. Here we describe the near-field contributions (first ~100 km from ridge) of pFe and Corg to the Southern East Pacific Rise (SEPR) Plume, one of the largest known Hydrothermal Plume features in the global ocean. Plume particles (>0.2 μm) were collected as part of the U.S. GEOTRACES Eastern Pacific Zonal Transect cruise (GP16) by in-situ filtration. Sediment cores were also collected to investigate the properties of settling particles. In this study, X-ray absorption near edge structure (XANES) spectroscopy was used in two complementary X-ray synchrotron approaches, scanning transmission X-ray microscopy (STXM) and X-ray microprobe, to investigate the Fe and C speciation of particles within the near-field non-buoyant SEPR Plume. When used in concert, STXM and X-ray microprobe provide fine-scale and representative information on particle morphology, elemental co-location, and chemical speciation. Bulk chemistry depth profiles for particulate Corg (POC), particulate manganese (pMn), and pFe indicated that the source of these materials to the non-buoyant Plume is Hydrothermal in origin. The Plume particles at stations within the first ~100 km down-stream of the ridge were composites of mineral (oxidized Fe) and biological materials (organic C, Corg). Iron chemistry in the Plume and in the core-top sediment fluff layer were both dominated by Fe(III) phases, such as Fe(III) oxyhydroxides and Fe(III) phyllosilicates. Particulate sulfur (pS) was a rare component of our Plume and sediment samples. When pS was detected, it was in the form of an Fe sulfide mineral phase, composing ≤0.4% of the Fe on a per atom basis. The sediment fluff layer contained a mixture of inorganic (coccolith fragments) and Corg bearing (lipid-rich biofilm-like) materials. The particle morphology and co-location of C and Fe in the sediment was different from that in Plume particles. This indicates that if the Fe-Corg composite particles settle rapidly to the sediments, then they experience strong alteration during settling and/or within the sediments. Overall, our observations indicate that the particles within the first ~100 km of the laterally advected Plume are S-depleted, Fe(III)-Corg composites indicative of a chemically oxidizing Plume with strong biological modification. These findings confirm that the Fe-Corg relationships observed for non-buoyant Plume particles within ~100 m of vent sites are representative of particles within the first ~100 km of the advecting non-buoyant Plume, and demonstrate that the export of Hydrothermal pFe is facilitated through physical-chemical association with Corg.
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Iron persistence in a distal Hydrothermal Plume supported by dissolved-particulate exchange
Nature Geoscience, 2017Co-Authors: Jessica N. Fitzsimmons, Christopher R German, Seth G. John, Chris M. Marsay, Colleen L. Hoffman, Sarah L. Nicholas, Brandy M. Toner, Robert M. SherrellAbstract:The largest known Hydrothermal Plume moves dissolved iron halfway across the Pacific. In situ measurements show that dissolved and particulate iron transport is facilitated by reversible exchange of dissolved iron onto organic compounds.
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geochemistry and iron isotope systematics of Hydrothermal Plume fall out at east pacific rise 9 50 n
Chemical Geology, 2016Co-Authors: Steven J Manganini, Brandy M. Toner, Olivier Rouxel, Christopher R GermanAbstract:Abstract While gross Hydrothermal fluxes entering the ocean are known to be significant, much remains unknown about the fate of this material as it disperses through the oceans, and its impact upon ocean biogeochemistry. Mineral precipitation within Hydrothermal Plumes removes Hydrothermally-sourced metals from solution and also acts to scavenge trace elements from the surrounding water column. Here, we investigate the fate of particulate Fe released from high-temperature Hydrothermal venting at EPR 9°50′N and its potential impact on local deep-ocean Fe-isotopic and geochemical budgets. We measured the geochemical composition, mineralogy and Fe isotope systematics of Hydrothermal Plume products in order to determine whether mineral precipitation imposes characteristic Fe-isotope “fingerprints” for Hydrothermally sourced Fe in the deep ocean. Our sampling includes sediment trap deployments after the eruptive event of Jan. 2006, allowing the examination of temporal changes of Hydrothermal fluxes over a 160 day period. Results show that Fe isotope composition in the high-temperature vent fluids is rather constant over the sampling period 2004–2008, and that secular variations of δ 56 Fe values of Plume particles from − 0.03 to − 0.91‰ (relative to IRMM-14 standard) could be explained by local processes leading to variable mixing extents of Hydrothermal, biogenic and lithogenic particles. Through geochemical modeling, we have calculated the relative abundances of Hydrothermal Plume components such as sulfides, Fe oxyhydroxides, organic matter, biogenic and lithogenic phases. We demonstrate that Fe isotope fractionation in the Hydrothermal Plume occurs during the formation and rapid settling of Fe-sulfides that are characterized by δ 56 Fe values ranging from − 0.73 ± 0.13‰ to − 0.86 ± 0.13‰, which is systematically lower than the end-member Hydrothermal fluids (δ 56 Fe = − 0.4‰). This study suggests that both the initial Fe isotope composition of the high-temperature vent fluids and its initial Fe/H 2 S ratio (i.e. Fe-sulfide precipitation versus Fe-oxyhydroxide precipitation) should impose characteristic Fe isotope “fingerprints” for Hydrothermally derived Fe in the deep ocean.
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Geochemistry and iron isotope systematics of Hydrothermal Plume fall-out at East Pacific Rise 9°50′N
Chemical Geology, 2016Co-Authors: Olivier Rouxel, Steven J Manganini, Brandy M. Toner, Christopher R GermanAbstract:Abstract While gross Hydrothermal fluxes entering the ocean are known to be significant, much remains unknown about the fate of this material as it disperses through the oceans, and its impact upon ocean biogeochemistry. Mineral precipitation within Hydrothermal Plumes removes Hydrothermally-sourced metals from solution and also acts to scavenge trace elements from the surrounding water column. Here, we investigate the fate of particulate Fe released from high-temperature Hydrothermal venting at EPR 9°50′N and its potential impact on local deep-ocean Fe-isotopic and geochemical budgets. We measured the geochemical composition, mineralogy and Fe isotope systematics of Hydrothermal Plume products in order to determine whether mineral precipitation imposes characteristic Fe-isotope “fingerprints” for Hydrothermally sourced Fe in the deep ocean. Our sampling includes sediment trap deployments after the eruptive event of Jan. 2006, allowing the examination of temporal changes of Hydrothermal fluxes over a 160 day period. Results show that Fe isotope composition in the high-temperature vent fluids is rather constant over the sampling period 2004–2008, and that secular variations of δ 56 Fe values of Plume particles from − 0.03 to − 0.91‰ (relative to IRMM-14 standard) could be explained by local processes leading to variable mixing extents of Hydrothermal, biogenic and lithogenic particles. Through geochemical modeling, we have calculated the relative abundances of Hydrothermal Plume components such as sulfides, Fe oxyhydroxides, organic matter, biogenic and lithogenic phases. We demonstrate that Fe isotope fractionation in the Hydrothermal Plume occurs during the formation and rapid settling of Fe-sulfides that are characterized by δ 56 Fe values ranging from − 0.73 ± 0.13‰ to − 0.86 ± 0.13‰, which is systematically lower than the end-member Hydrothermal fluids (δ 56 Fe = − 0.4‰). This study suggests that both the initial Fe isotope composition of the high-temperature vent fluids and its initial Fe/H 2 S ratio (i.e. Fe-sulfide precipitation versus Fe-oxyhydroxide precipitation) should impose characteristic Fe isotope “fingerprints” for Hydrothermally derived Fe in the deep ocean.
Edward T. Baker - One of the best experts on this subject based on the ideXlab platform.
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understanding a submarine eruption through time series Hydrothermal Plume sampling of dissolved and particulate constituents west mata 2008 2012
Geochemistry Geophysics Geosystems, 2014Co-Authors: Edward T. Baker, J E Lupton, Marvin D Lilley, Tamara Baumberger, Joseph A Resing, David A Butterfield, E J Olson, Gretchen L FruhgreenAbstract:Four cruises between 2008 and 2012 monitored the continuing eruption of West Mata volcano in the NE Lau Basin as it produced Plumes of chemically altered water above its summit. Although large enrichments in 3He, CO2, Fe, and Mn were observed in the Plumes, the most notable enrichment was that of H2, which reached concentrations as high as 14,843 nM. Strongly enriched H2 concentrations in the water column result from reactions between seawater or magmatic water and extremely hot rocks. In 2008, the observation of elevated H2 concentrations in the water column above West Mata pointed to vigorous ongoing eruptions at the volcano's summit. The eruption was confirmed by visual observations made by the ROV Jason 2 in 2009 and demonstrated that H2 measurements are a vital instrument to detect ongoing volcanic eruptions at the seafloor. Elevated H2 in 2010 showed that the eruption was ongoing, although at a reduced level given a maximum H2 concentration of 4410 nM. In 2012, H2 levels in the water column declined significantly, to a maximum of only 7 nM, consistent with visual observations from the Quest-4000 ROV that found no evidence of an ongoing volcanic eruption. Methane behaved independently of other measured gases and its concentrations in the Hydrothermal Plume were very low. We attribute its minimal enrichments to a mixture of mantle carbon reduced to CH4 and biological CH4 from diffuse flow sites. This study demonstrates that ongoing submarine volcanic eruptions are characterized by high dissolved H2 concentrations present in the overlying water column.
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rapid dispersal of a Hydrothermal Plume by turbulent mixing
Deep Sea Research Part I: Oceanographic Research Papers 57 (8). pp. 931-945., 2010Co-Authors: Maren Walter, Christopher R German, Christian Mertens, Uwe Stober, Dana R Yoerger, Jurgen Sultenfus, Monika Rhein, Bernd Melchert, Edward T. BakerAbstract:The water column imprint of the Hydrothermal Plume observed at the Nibelungen field (8 18'S 13 degrees 30'W) is highly variable in space and time. The off-axis location of the site, along the southern boundary of a non-transform ridge offset at the joint between two segments of the southern Mid-Atlantic Ridge, is characterized by complex, rugged topography, and thus favorable for the generation of internal tides, subsequent internal wave breaking, and associated vertical mixing in the water column. We have used towed transects and vertical profiles of stratification, turbidity, and direct current measurements to investigate the strength of turbulent mixing in the vicinity of the vent site and the adjacent rift valley, and its temporal and spatial variability in relation to the Plume dispersal. Turbulent diffusivities K(rho) were calculated from temperature inversions via Thorpe scales. Heightened mixing (compared to open ocean values) was observed in the whole rift valley within an order of K(rho) around 10(-3) m(2) s(-1). The mixing close to the vent site was even more elevated, with an average of K(rho) = 4 x 10(-2) m(2) s(-1). The mixing, as well as the flow field, exhibited a strong tidal cycle, with strong currents and mixing at the non-buoyant Plume level during ebb flow. Periods of strong mixing were associated with increased internal wave activity and frequent occurrence of turbulent overturns. Additional effects of mixing on Plume dispersal include bifurcation of the particle Plume, likely as a result of the interplay between the modulated mixing strength and current speed, as well as high frequency internal waves in the effluent Plume layer, possibly triggered by the buoyant Plume via nonlinear interaction with the elevated background turbulence or penetrative convection. (C) 2010 Elsevier Ltd. All rights reserved.
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geochemical and physical structure of the Hydrothermal Plume at the ultramafic hosted logatchev Hydrothermal field at 14 45 n on the mid atlantic ridge
Marine Geology, 2010Co-Authors: Herwig Marbler, Edward T. Baker, Andrea Koschinsky, Thomas Pape, Richard Seifert, Stefan Weber, L M De Carvalho, K SchmidtAbstract:Abstract The Hydrothermal Plume generated in deep waters above the Logatchev Hydrothermal field (LHF) about 15°N on the Mid-Atlantic Ridge was investigated and mapped for its 3D distributions using a combination of in situ optical light scattering data, temperature and salinity data, as well as concentrations of hydrogen, methane, total dissolvable Fe, and total dissolvable Mn. Based on the results obtained for these meaningful parameters, we report the geochemical and physical characteristics of the fluids expelled from the ultramafic LHF and the chemical structure of its Hydrothermal Plume in the water column. The Hydrothermal Plume is sourced by at least seven distinct vent sites and possibly additional diffusive fluid and gas discharge. It comprises a water body characterized by strong nephelometric anomalies (expressed as ∆NTU, nephelometric turbidity units) and high concentrations of Fe and Mn (> 5 times seawater concentration), and the gas Plume with several times the H 2 and CH 4 concentrations of normal seawater. Up to three Plume levels with a total vertical extension of about 350 m from the seafloor were classified in the Hydrothermal Plume. The ∆NTU Plume could be followed to approximately 2.5 km to the north and to the south from the vent site while the gas Plume spread several km farther from the Hydrothermal source. High concentrations of H 2 (up to 1598 nmol l − 1 ) and CH 4 (up to 323 nmol l − 1 ) accompanied by relatively low dissolvable Fe concentrations (up to 270 nmol l − 1 ) as well as low concentrations of dissolvable Mn (112 nmol l − 1 ) compared to basaltic Hydrothermal systems are the characteristics of the Plume. The low metal/gas ratios showed a decrease with increasing distance from the vent site. Our data demonstrate that ultramafic systems such as the LHF serve both as sources and sinks for elements, with respect to metal and gas inputs into the oceanic water column. The relevance of such systems is underlined by the discovery (and postulated frequency) of further ultramafic-hosted Hydrothermal systems on slow-spreading ridges.
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Geochemical and physical structure of the Hydrothermal Plume at the ultramafic-hosted Logatchev Hydrothermal field at 14°45'N on the Mid-Atlantic Ridge
Marine Geology, 2010Co-Authors: Herwig Marbler, Edward T. Baker, Andrea Koschinsky, Thomas Pape, Richard Seifert, Stefan Weber, L M De Carvalho, K SchmidtAbstract:Abstract The Hydrothermal Plume generated in deep waters above the Logatchev Hydrothermal field (LHF) about 15°N on the Mid-Atlantic Ridge was investigated and mapped for its 3D distributions using a combination of in situ optical light scattering data, temperature and salinity data, as well as concentrations of hydrogen, methane, total dissolvable Fe, and total dissolvable Mn. Based on the results obtained for these meaningful parameters, we report the geochemical and physical characteristics of the fluids expelled from the ultramafic LHF and the chemical structure of its Hydrothermal Plume in the water column. The Hydrothermal Plume is sourced by at least seven distinct vent sites and possibly additional diffusive fluid and gas discharge. It comprises a water body characterized by strong nephelometric anomalies (expressed as ∆NTU, nephelometric turbidity units) and high concentrations of Fe and Mn (> 5 times seawater concentration), and the gas Plume with several times the H 2 and CH 4 concentrations of normal seawater. Up to three Plume levels with a total vertical extension of about 350 m from the seafloor were classified in the Hydrothermal Plume. The ∆NTU Plume could be followed to approximately 2.5 km to the north and to the south from the vent site while the gas Plume spread several km farther from the Hydrothermal source. High concentrations of H 2 (up to 1598 nmol l − 1 ) and CH 4 (up to 323 nmol l − 1 ) accompanied by relatively low dissolvable Fe concentrations (up to 270 nmol l − 1 ) as well as low concentrations of dissolvable Mn (112 nmol l − 1 ) compared to basaltic Hydrothermal systems are the characteristics of the Plume. The low metal/gas ratios showed a decrease with increasing distance from the vent site. Our data demonstrate that ultramafic systems such as the LHF serve both as sources and sinks for elements, with respect to metal and gas inputs into the oceanic water column. The relevance of such systems is underlined by the discovery (and postulated frequency) of further ultramafic-hosted Hydrothermal systems on slow-spreading ridges.
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rapid dike emplacement leads to eruptions and Hydrothermal Plume release during seafloor spreading events
Geology, 2007Co-Authors: Robert P Dziak, Edward T. Baker, James P Cowen, Delwayne R Bohnenstiehl, K H Rubin, J H Haxel, M J FowlerAbstract:The creation of ocean crust by rapid injection of magma at mid-ocean ridges can lead to eruptions of lava onto the seafloor and release of “event Plumes,” which are huge volumes of anomalously warm water enriched in reduced chemicals that rise up to 1 km above the seafloor. Here, we use seismic data to show that seafloor eruptions and the release of Hydrothermal event Plumes correspond to diking episodes with high injection velocities and rapid onset of magma emplacement within the rift zone. These attributes result from high excess magma pressure at the dike source, likely due to a new influx of melt from the mantle. These dynamic magmatic conditions can be detected remotely and may predict the likelihood of event Plume release during future seafloor spreading events.
Richard E Thomson - One of the best experts on this subject based on the ideXlab platform.
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compositional variability in the ascending fluxes from a Hydrothermal Plume
Journal of Geophysical Research, 2002Co-Authors: Miriam A Bertram, Richard E Thomson, James P Cowen, Richard A FeelyAbstract:[1] Sequentially sampling sediment traps set with 33 day sampling intervals were deployed with current meters on three moorings in the northeast Pacific Ocean between July 1994 and May 1995. One mooring was deployed near the Main Vent field on Endeavour Ridge (On-Axis site, 47°57.0′N, 129°05.7′W), a second, 3 km west of the Main vent site (West site), and the third, 43 km northeast of the Main vent site (East or background site). Ascending and descending particles were collected near 1600 and 2000 m depth, well above and within the top of laterally spreading Hydrothermal Plumes. The elemental composition of particles was used to evaluate their origins: biogenic fluxes were indicated by elevated Ca or Si, Hydrothermal fluxes by elevated Fe, Mn, and Cu, and lithogenic fluxes by elevated Ti. We link temporal variability in both the ascending and descending particle composition and flux to variations in lateral transport of Hydrothermal constituents and to seasonal drawdown of Hydrothermal Plume particles by biogenic material from the upper ocean. The relatively low Hydrothermal Fe content of ascending material late in the experiment is thought to be due to uptake by descending biogenic material. These results suggest that seasonal productivity and particle export from the ocean surface can modulate the Hydrothermal flux of elements to the waters above and to the sediments below.
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Ascending and descending particle flux from Hydrothermal Plumes at Endeavour Segment, Juan de Fuca Ridge
Deep Sea Research Part I: Oceanographic Research Papers, 2001Co-Authors: James P Cowen, Edward T. Baker, Richard E Thomson, Miriam A Bertram, Stuart G Wakeham, J. William Lavelle, Richard A FeelyAbstract:Abstract Bio-acoustic surveys and associated zooplankton net tows have documented anomalously high concentrations of zooplankton within a 100 m layer above the Hydrothermal Plumes at Endeavour Segment, Juan de Fuca Ridge. These and other data suggest that congregating epi-Plume zooplankton are exploiting a food substrate associated with the Hydrothermal Plume. Ascending, organic-rich particles could provide a connection. Consequently, two paired sequentially sampling ascending and descending particle flux traps and a current meter were deployed on each of three moorings from July 1994 to May 1995. Mooring sites included an on-axis site (OAS; 47°57.0′N, 129°05.7′W) near the main Endeavour vent field, a “down-current” site 3 km west of the main vent field (WS), and a third background station 43 km northeast of the vent field (ES). Significant ascending and descending particle fluxes were measured at all sites and depths. Lipid analyses indicated that ascending POC was derived from mid-depth and deep zooplankton whereas descending POC also contained a component of photosynthetically derived products from the sea surface. Highest ascending POC fluxes were found at the Hydrothermal Plume-swept sites (OAS and WS). The limited data available, however, precludes an unequivocal conclusion that Hydrothermal processes contribute to the ascending flux of organic carbon at each site. Highest ascending to descending POC flux ratios were also found at WS. Observed trends in POC, PMn/PTi, and PFe/PTi clearly support a Hydrothermal component to the descending flux at the Plume-swept WS site (no descending data was recovered at OAS) but not at the background ES site. Alternative explanations for ascending particle data are discussed. First-order calculations for the organic carbon input (5–22 mg C m−2 d−1) required to sustain observed epi-Plume zooplankton anomalies at Endeavour are comparable both to measured total POC flux to epi-Plume depths (2–5 mg C m−2 d−1: combined Hydrothermal and surface derived organic carbon) and to estimates of the total potential in situ organic carbon production (2–9 mg C m−2 d−1) from microbial oxidation of Hydrothermal Plume H2, CH4 and NH4+.
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lipid rich ascending particles from the Hydrothermal Plume at endeavour segment juan de fuca ridge
Geochimica et Cosmochimica Acta, 2001Co-Authors: Stuart G Wakeham, Brenda J Burd, James P Cowen, Richard E ThomsonAbstract:Abstract Samples of ascending and descending particulate matter from the Hydrothermal Plume at Endeavour Segment of the Juan de Fuca Ridge were analyzed for their lipid composition to investigate the biogeochemistry of particulate matter associated with oceanic Hydrothermal processes. The ascending flux of lipid was up to ≈ six-fold greater than the descending flux, and ascending particles were significantly enriched up to ≈200-fold in lipid compared with descending particles. The dominant fatty acids in both ascending and descending particles were C16:1, C18:1ω9, C20:1, and C22:1, and the major neutral lipids were C20:1 and C22:1 fatty alcohols and cholesterol. C20:1 and C22:1 alcohols constituted up to >70% of neutral lipids in ascending particles at sites directly influenced by the Plume, compared to 54% at the background site and 35 to 54% in descending particles. Comparison with zooplankton collected above the Plume suggested that a large fraction of this lipid was derived from zooplankton that may be opportunistically feeding on organic matter associated with the Plume. The high flux of lipid moving upward in the water column in the vicinity of the vent Plume is roughly equivalent to downward fluxes at similar oceanic depths and suggests an important mechanism by which particulate lipids may be dispersed in the marine water column.
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Elevated NH+4 in a neutrally buoyant Hydrothermal Plume
Deep Sea Research Part I: Oceanographic Research Papers, 1998Co-Authors: James P Cowen, Ronald D Jones, Richard E ThomsonAbstract:Anomalously high concentrations of NH+4 in Hydrothermal vent discharge fluids were tracked in the resulting neutrally buoyant Plume over the unsedimented Endeavour Segment, Juan de Fuca Ridge. Vertical profiles of NH+4 concentrations showed Plume depth (∼2025 m) maxima of nearly 400 nM over the Endeavour Segment’s main vent field, on the same order as most subsurface NH+4 maxima. Plume NH+4 values decreased to just above background deep water values (50–70 nM) in older Plume water at a station 15 km southwest of the vent field, although most of the Plume NH+4 appears to be transported beyond the ridge axial valley. Preliminary net specific NH+4 removal rates determined within the Plume maximum (0.04–0.13 d-1) and corresponding turnover times (8–28 d) are similar to values for CH4 oxidation rates. The data suggest that NH+4 may be a significant substrate for in situ chemolithotrophic production of organic matter in the Endeavour Segment Hydrothermal Plume.
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distribution of zooplankton associated with the endeavour ridge Hydrothermal Plume
Journal of Plankton Research, 1995Co-Authors: Brenda J Burd, Richard E ThomsonAbstract:Enhanced zooplankton biomass was found in shallow ( 900 m) net samples collected over the Endeavour Ridge Hydrothermal Plume in 1991 and 1992. This enhanced biomass was manifest in considerably higher abundance values for most species in proximity to the vent field compared with abundance values from net samples collected 10-50 km off-axis. The species most enriched in abundance by the Hydrothermal Plume were those normally found in the mid-depth scattering layer at 400- 900 m depth. These mid-depth animals were also the dominant fauna in the deep scattering layers that overlie the Hydrothermal Plume at depths of 1200-1900 m near the main vent field. The abundance and biomass dominants were species with pronounced ontogenetic migration patterns, and their associated predators. The abundance of many typically deep species was also enhanced over the main vent field. Faunal compositions of net samples were compared using a similarity measure and average linkage rule. Deep fauna in proximity to the vent field but not associated with scattering layers (Group 1), were similar to deep fauna 10-50 km off- axis. The fauna of the deep scattering layer over the vent field (Group 2) was most similaT to surface and mid- depth scattering layer fauna found within a 50 km radius of the vent field. Statistical tests of linkages obtained using a bootstrap method indicate that the abundance and taxonomic composition of the two faunal groups were significantly distinct in 1992, but not in 1991. We conclude that there was considerable infiltration of shallow fauna into the deep scattering layers within 2-3 km of the main vent field, less extensive infiltration 10-15 km to the north and south of the vent field in 1991, and insignificant infiltration at stations 50 km to the west of the vent field in 1992. A bootstrap analysis comparing the faunal composition of nets towed above 900 m depth showed that shallow fauna were not significantly distinct between the two sampling years or up to 50 km away from the vent field.
Richard A Feely - One of the best experts on this subject based on the ideXlab platform.
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compositional variability in the ascending fluxes from a Hydrothermal Plume
Journal of Geophysical Research, 2002Co-Authors: Miriam A Bertram, Richard E Thomson, James P Cowen, Richard A FeelyAbstract:[1] Sequentially sampling sediment traps set with 33 day sampling intervals were deployed with current meters on three moorings in the northeast Pacific Ocean between July 1994 and May 1995. One mooring was deployed near the Main Vent field on Endeavour Ridge (On-Axis site, 47°57.0′N, 129°05.7′W), a second, 3 km west of the Main vent site (West site), and the third, 43 km northeast of the Main vent site (East or background site). Ascending and descending particles were collected near 1600 and 2000 m depth, well above and within the top of laterally spreading Hydrothermal Plumes. The elemental composition of particles was used to evaluate their origins: biogenic fluxes were indicated by elevated Ca or Si, Hydrothermal fluxes by elevated Fe, Mn, and Cu, and lithogenic fluxes by elevated Ti. We link temporal variability in both the ascending and descending particle composition and flux to variations in lateral transport of Hydrothermal constituents and to seasonal drawdown of Hydrothermal Plume particles by biogenic material from the upper ocean. The relatively low Hydrothermal Fe content of ascending material late in the experiment is thought to be due to uptake by descending biogenic material. These results suggest that seasonal productivity and particle export from the ocean surface can modulate the Hydrothermal flux of elements to the waters above and to the sediments below.
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Ascending and descending particle flux from Hydrothermal Plumes at Endeavour Segment, Juan de Fuca Ridge
Deep Sea Research Part I: Oceanographic Research Papers, 2001Co-Authors: James P Cowen, Edward T. Baker, Richard E Thomson, Miriam A Bertram, Stuart G Wakeham, J. William Lavelle, Richard A FeelyAbstract:Abstract Bio-acoustic surveys and associated zooplankton net tows have documented anomalously high concentrations of zooplankton within a 100 m layer above the Hydrothermal Plumes at Endeavour Segment, Juan de Fuca Ridge. These and other data suggest that congregating epi-Plume zooplankton are exploiting a food substrate associated with the Hydrothermal Plume. Ascending, organic-rich particles could provide a connection. Consequently, two paired sequentially sampling ascending and descending particle flux traps and a current meter were deployed on each of three moorings from July 1994 to May 1995. Mooring sites included an on-axis site (OAS; 47°57.0′N, 129°05.7′W) near the main Endeavour vent field, a “down-current” site 3 km west of the main vent field (WS), and a third background station 43 km northeast of the vent field (ES). Significant ascending and descending particle fluxes were measured at all sites and depths. Lipid analyses indicated that ascending POC was derived from mid-depth and deep zooplankton whereas descending POC also contained a component of photosynthetically derived products from the sea surface. Highest ascending POC fluxes were found at the Hydrothermal Plume-swept sites (OAS and WS). The limited data available, however, precludes an unequivocal conclusion that Hydrothermal processes contribute to the ascending flux of organic carbon at each site. Highest ascending to descending POC flux ratios were also found at WS. Observed trends in POC, PMn/PTi, and PFe/PTi clearly support a Hydrothermal component to the descending flux at the Plume-swept WS site (no descending data was recovered at OAS) but not at the background ES site. Alternative explanations for ascending particle data are discussed. First-order calculations for the organic carbon input (5–22 mg C m−2 d−1) required to sustain observed epi-Plume zooplankton anomalies at Endeavour are comparable both to measured total POC flux to epi-Plume depths (2–5 mg C m−2 d−1: combined Hydrothermal and surface derived organic carbon) and to estimates of the total potential in situ organic carbon production (2–9 mg C m−2 d−1) from microbial oxidation of Hydrothermal Plume H2, CH4 and NH4+.
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Hydrothermal Plume particles and dissolved phosphate over the superfast spreading southern east pacific rise
Geochimica et Cosmochimica Acta, 1996Co-Authors: Richard A Feely, Jun Ichiro Ishibashi, Edward T. Baker, Katsumi Marumo, Tetsuro Urabe, James F Gendron, Geoffrey T Lebon, Kei OkamuraAbstract:Abstract The distribution and elemental composition of Hydrothermal Plume particles were mapped along the superfast spreading southern East Pacific Rise from the Garret Transform Fault to ∼19°S. Hydrographic and optical data were obtained using a series of seven tow-yos and thirty vertical casts employing a rosette sampler with 19-L PVC bottles for collecting discrete samples of various dissolved and particulate Hydrothermal species. The extent of Hydrothermal Plume coverage over the southern East Pacific Rise between 13°33′ and 18°40′S is significantly greater than in other ridgecrest systems. The region south of 17°20′S is characterized by significant enrichments of volatile gases resulting from magmatic input of fresh lava at the seafloor. Between 17°20′ and 18°40′S, the ratio of S Fe in the Plume particles is highly correlated with the dissolved gases in the neutrally-buoyant Hydrothermal Plumes. Plume inventories of Fe and S over this portion of the southern East Pacific Rise are 6–150 times higher than what has been observed over other vent fields because the total abundance of Plumes is much greater. In addition, significant depletions (> 100 nmol/L) of dissolved phosphate over the ridge axis were observed at the depth of the Hydrothermal Plumes. These results provide clear evidence that this section of the southern East Pacific Rise maintains the most extensive complex of Hydrothermal Plumes observed thus far on the global ridgecrest system.
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composition and sedimentation of Hydrothermal Plume particles from north cleft segment juan de fuca ridge
Journal of Geophysical Research, 1994Co-Authors: Richard A Feely, Edward T. Baker, Gary J Massoth, John H Trefry, Anthony J Paulson, Geoffrey T LebonAbstract:In 1990 and 1991, particles from buoyant and neutrally buoyant Hydrothermal Plumes above Hydrothermal vents at the North Cleft segment of the Juan de Fuca Ridge were sampled to study their changing composition and fluxes away from the vent field. In the rising buoyant Plume, >75% of the P, V, Cr, and As scavenging from seawater by Hydrothermal precipitates occurs in the first 50 m above the vent. Cu and Zn are most enriched in buoyant Plume particles collected from the first few meters above the vent. However, the degree of enrichment decreases very rapidly with increased height above the vents due to sedimentation of the more dense Cu- and Zn-rich sulfide phases. Using the Plume data, coupled with the results of our analysis of sediment trap samples, we estimated that more than 99% and 99.9%, respectively, of the total Hydrothermal Fe and Mn produced at the vent field are transported beyond the vent field and dispersed in the open ocean.
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distribution and composition of Hydrothermal Plume particles from the ashes vent field at axial volcano juan de fuca ridge
Journal of Geophysical Research, 1990Co-Authors: Richard A Feely, Edward T. Baker, T L Geiselman, Gary J Massoth, S R HammondAbstract:In 1986 and 1987, buoyant and neutrally buoyant Hydrothermal Plume particles from the ASHES vent field within Axial Volcano were sampled to study their variations in composition with height above the seafloor. Individual mineral phases were identified using standard X ray diffraction procedures. Elemental composition and particle morphologies were determined by X ray fluorescence spectrometry and scanning electron microscopy/X ray energy spectrometry techniques. The vent particles were primarily composed of sphalerite, anhydrite, pyrite, pyrrhotite, chalcopyrite, barite, hydrous iron oxides, and amorphous silica. Grain size analyses of buoyant Plume particles showed rapid particle growth in the first few centimeters above the vent orifice, followed by differential sedimentation of the larger sulfide and sulfate minerals out of the buoyant Plume. The neutrally buoyant Plume consisted of a lower Plume, which was highly enriched in Fe, S, Zn, and Cu, and an upper Plume, which was highly enriched in Fe and Mn. The upper Plume was enriched in Fe and Mn oxyhydroxide particles, and the lower Plume was enriched in suspended sulfide particles in addition to the Fe and Mn oxyhydroxide particles. The chemical data for the water column particles indicate that chemical scavenging and differential sedimentation processes are major factors controlling the composition of the dispersing Hydrothermal particles. Short-term sediment trap experiments indicate that the fallout from the ASHES vent field is not as large as some of the other vent fields on the Juan de Fuca Ridge.
Brandy M. Toner - One of the best experts on this subject based on the ideXlab platform.
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dynamic biogeochemistry of the particulate sulfur pool in a buoyant deep sea Hydrothermal Plume
ACS Earth and Space Chemistry, 2020Co-Authors: Brandi R Cron, Christopher R German, Gregory J Dick, Cody S Sheik, Fotioschristos A Kafantaris, Gregory K Druschel, Jeffrey S Seewald, John A Breier, Brandy M. TonerAbstract:In deep-ocean Hydrothermal vent systems, oxidation–reduction (redox) reactions involving sulfur are known to fuel primary production via chemosynthesis. The particulate sulfur pool within buoyant Hydrothermal Plumes available to microorganisms as metabolic substrates remains undescribed. In this study, buoyant Hydrothermal Plume particles were collected from the Von Damm Vent Field, Mid-Cayman Rise, Caribbean. A novel in situ filtration system and remotely operated vehicle were used to collect samples along vertical profiles above two sites close to the summit of Mount Dent. Particulate sulfur speciation was measured using sulfur 1s X-ray absorption near edge structure (XANES) spectroscopy. The activity of sulfur-cycling genes in the buoyant Plume was measured using metatranscriptomic sequencing. Our results indicate that both solid-state sulfur chemistry and microbial activity within the Von Damm buoyant Plume are dynamic and diverse over short temporal and spatial scales. The particulate sulfur species ...
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near field iron and carbon chemistry of non buoyant Hydrothermal Plume particles southern east pacific rise 15 s
Marine Chemistry, 2018Co-Authors: Colleen L. Hoffman, Christopher R German, Jessica N. Fitzsimmons, Sarah L. Nicholas, Robert M. Sherrell, Maija Heller, Daniel C Ohnemus, Brandy M. TonerAbstract:Abstract Iron (Fe)-poor surface waters limit phytoplankton growth and their ability to remove carbon (C) from the atmosphere and surface ocean. Over the past few decades, research has focused on constraining the global Fe cycle and its impacts on the global C cycle. Hydrothermal vents have become a highly debated potential source of Fe to the surface ocean. Two main mechanisms for transport of Fe over long distances have been proposed: Fe-bearing nanoparticles and organic C complexation with Fe in the dissolved (dFe) and particulate (pFe) pools. However, the ubiquity and importance of these processes is unknown at present, and very few vents have been investigated for Fe-Corg interactions or the transport of such materials away from the vent. Here we describe the near-field contributions (first ~100 km from ridge) of pFe and Corg to the Southern East Pacific Rise (SEPR) Plume, one of the largest known Hydrothermal Plume features in the global ocean. Plume particles (>0.2 μm) were collected as part of the U.S. GEOTRACES Eastern Pacific Zonal Transect cruise (GP16) by in-situ filtration. Sediment cores were also collected to investigate the properties of settling particles. In this study, X-ray absorption near edge structure (XANES) spectroscopy was used in two complementary X-ray synchrotron approaches, scanning transmission X-ray microscopy (STXM) and X-ray microprobe, to investigate the Fe and C speciation of particles within the near-field non-buoyant SEPR Plume. When used in concert, STXM and X-ray microprobe provide fine-scale and representative information on particle morphology, elemental co-location, and chemical speciation. Bulk chemistry depth profiles for particulate Corg (POC), particulate manganese (pMn), and pFe indicated that the source of these materials to the non-buoyant Plume is Hydrothermal in origin. The Plume particles at stations within the first ~100 km down-stream of the ridge were composites of mineral (oxidized Fe) and biological materials (organic C, Corg). Iron chemistry in the Plume and in the core-top sediment fluff layer were both dominated by Fe(III) phases, such as Fe(III) oxyhydroxides and Fe(III) phyllosilicates. Particulate sulfur (pS) was a rare component of our Plume and sediment samples. When pS was detected, it was in the form of an Fe sulfide mineral phase, composing ≤0.4% of the Fe on a per atom basis. The sediment fluff layer contained a mixture of inorganic (coccolith fragments) and Corg bearing (lipid-rich biofilm-like) materials. The particle morphology and co-location of C and Fe in the sediment was different from that in Plume particles. This indicates that if the Fe-Corg composite particles settle rapidly to the sediments, then they experience strong alteration during settling and/or within the sediments. Overall, our observations indicate that the particles within the first ~100 km of the laterally advected Plume are S-depleted, Fe(III)-Corg composites indicative of a chemically oxidizing Plume with strong biological modification. These findings confirm that the Fe-Corg relationships observed for non-buoyant Plume particles within ~100 m of vent sites are representative of particles within the first ~100 km of the advecting non-buoyant Plume, and demonstrate that the export of Hydrothermal pFe is facilitated through physical-chemical association with Corg.
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iron persistence in a distal Hydrothermal Plume supported by dissolved particulate exchange
Nature Geoscience, 2017Co-Authors: Jessica N. Fitzsimmons, Seth G. John, Chris M. Marsay, Colleen L. Hoffman, Sarah L. Nicholas, Brandy M. TonerAbstract:Hydrothermally sourced dissolved metals have been recorded in all ocean basins. In the oceans’ largest known Hydrothermal Plume, extending westwards across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same Plume also exceed background concentrations, even 4,000 km from the vent source. Both dissolved and particulate iron deepen by more than 350 m relative to 3He—a non-reactive tracer of Hydrothermal input—crossing isopycnals. Manganese shows no similar descent. Individual Plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5–10 m yr−1. Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe(III) oxyhydroxides, whereas dissolved iron consists of nanoparticulate Fe(III) oxyhydroxides and an organically complexed iron phase. The descent of Plume-dissolved iron is best explained by reversible exchange onto slowly sinking particles, probably mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles. The largest known Hydrothermal Plume moves dissolved iron halfway across the Pacific. In situ measurements show that dissolved and particulate iron transport is facilitated by reversible exchange of dissolved iron onto organic compounds.
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Iron persistence in a distal Hydrothermal Plume supported by dissolved-particulate exchange
Nature Geoscience, 2017Co-Authors: Jessica N. Fitzsimmons, Christopher R German, Seth G. John, Chris M. Marsay, Colleen L. Hoffman, Sarah L. Nicholas, Brandy M. Toner, Robert M. SherrellAbstract:The largest known Hydrothermal Plume moves dissolved iron halfway across the Pacific. In situ measurements show that dissolved and particulate iron transport is facilitated by reversible exchange of dissolved iron onto organic compounds.
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geochemistry and iron isotope systematics of Hydrothermal Plume fall out at east pacific rise 9 50 n
Chemical Geology, 2016Co-Authors: Steven J Manganini, Brandy M. Toner, Olivier Rouxel, Christopher R GermanAbstract:Abstract While gross Hydrothermal fluxes entering the ocean are known to be significant, much remains unknown about the fate of this material as it disperses through the oceans, and its impact upon ocean biogeochemistry. Mineral precipitation within Hydrothermal Plumes removes Hydrothermally-sourced metals from solution and also acts to scavenge trace elements from the surrounding water column. Here, we investigate the fate of particulate Fe released from high-temperature Hydrothermal venting at EPR 9°50′N and its potential impact on local deep-ocean Fe-isotopic and geochemical budgets. We measured the geochemical composition, mineralogy and Fe isotope systematics of Hydrothermal Plume products in order to determine whether mineral precipitation imposes characteristic Fe-isotope “fingerprints” for Hydrothermally sourced Fe in the deep ocean. Our sampling includes sediment trap deployments after the eruptive event of Jan. 2006, allowing the examination of temporal changes of Hydrothermal fluxes over a 160 day period. Results show that Fe isotope composition in the high-temperature vent fluids is rather constant over the sampling period 2004–2008, and that secular variations of δ 56 Fe values of Plume particles from − 0.03 to − 0.91‰ (relative to IRMM-14 standard) could be explained by local processes leading to variable mixing extents of Hydrothermal, biogenic and lithogenic particles. Through geochemical modeling, we have calculated the relative abundances of Hydrothermal Plume components such as sulfides, Fe oxyhydroxides, organic matter, biogenic and lithogenic phases. We demonstrate that Fe isotope fractionation in the Hydrothermal Plume occurs during the formation and rapid settling of Fe-sulfides that are characterized by δ 56 Fe values ranging from − 0.73 ± 0.13‰ to − 0.86 ± 0.13‰, which is systematically lower than the end-member Hydrothermal fluids (δ 56 Fe = − 0.4‰). This study suggests that both the initial Fe isotope composition of the high-temperature vent fluids and its initial Fe/H 2 S ratio (i.e. Fe-sulfide precipitation versus Fe-oxyhydroxide precipitation) should impose characteristic Fe isotope “fingerprints” for Hydrothermally derived Fe in the deep ocean.
