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  • 11
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    PANGAEA
    In:  Supplement to: Hawkes, Jeffrey A; Rossel, Pamela E; Stubbins, Aron; Butterfield, David A; Connelly, Douglas P; Achterberg, Eric Pieter; Koschinsky, Andrea; Chavagnac, Valerie; Hansen, Christian T; Bach, Wolfgang; Dittmar, Thorsten (2015): Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation. Nature Geoscience, 8(11), 856-860, https://doi.org/10.1038/ngeo2543
    Publication Date: 2024-02-17
    Description: Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood (Dittmar and Stubbins, 2014; Hansell, 2013, doi:10.1146/annurev-marine-120710-100757). Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years (Elderfield and Schultz, 1996, doi:10.1146/annurev.earth.24.1.191).
    Keywords: Akademik Mstislav Keldysh; AMK47; AMK47-Lost_City; AT18-08; Atlantis (1997); Carbon, organic, dissolved; Carbon, organic, dissolved, extracted; Comment; Comment 2 (continued); Contamination; CTD/Rosette; CTD-RO; Description; Error; Event label; Factor; Identification; ISIS; ISIS MS2000; J2-574; J2-575; J2-576; J2-579; J2-580; J2-581; J2-583; James Cook; JC042; JC080; JC082; JC42_ISIS_130; JC42_ISIS_133; JC42_ISIS_134; JC42_ISIS_141; JC80_015_CTD; JC80_ISIS_189; JC80_ISIS_190; JC80_ISIS_194; JC82_ISIS_198; JC82_ISIS_200; JC82_ISIS_202; JC82_ISIS_204; JC82_ISIS_206; JC82_ISIS_207; Juan_de_Fuca_Ridge_Axial; Juan_de_Fuca_Ridge_Endeavour; Latitude of event; Lithology/composition/facies; Longitude of event; Lost City Hydrothermal Field, Mid-Atlantic Ridge; M82/3; M82/3_719-1; M82/3_722-1; M82/3_739-1; M82/3_756-1; Magnesium; Maria S. Merian; Meteor (1986); MIR; MIR deep-sea manned submersible; MSM10/3; MSM10/3_290ROV-11; MSM10/3_300; MSM10/3_313ROV-12; Name; Ocean and sea region; Percentage; Precision; Remote operated vehicle; Remote operated vehicle Jason II; ROV; ROVJ; Sample type; Sample volume; Sampling date; Site; Solid phase extractable; South Atlantic Ocean; tropical/subtropical North Atlantic; Type; Volume; Wakamiko_Crater
    Type: Dataset
    Format: text/tab-separated-values, 4130 data points
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  • 12
    Publication Date: 2021-04-23
    Description: Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood. Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401°C. In laboratory experiments, where we heated samples to 380°C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years
    Type: Article , PeerReviewed
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  • 13
    Publication Date: 2023-02-08
    Description: The vast majority of freshly produced oceanic dissolved organic carbon (DOC) is derived from marine phytoplankton, then rapidly recycled by heterotrophic microbes. A small fraction of this DOC survives long enough to be routed to the interior ocean, which houses the largest and oldest DOC reservoir. DOC reactivity depends upon its intrinsic chemical composition and extrinsic environmental conditions. Therefore, recalcitrance is an emergent property of DOC that is analytically difficult to constrain. New isotopic techniques that track the flow of carbon through individual organic molecules show promise in unveiling specific biosynthetic or degradation pathways that control the metabolic turnover of DOC and its accumulation in the deep ocean. However, a multivariate approach is required to constrain current carbon fluxes so that we may better predict how the cycling of oceanic DOC will be altered with continued climate change. Ocean warming, acidification, and oxygen depletion may upset the balance between the primary production and heterotrophic reworking of DOC, thus modifying the amount and/or composition of recalcitrant DOC. Climate change and anthropogenic activities may enhance mobilization of terrestrial DOC and/or stimulate DOC production in coastal waters, but it is unclear how this would affect the flux of DOC to the open ocean. Here, we assess current knowledge on the oceanic DOC cycle and identify research gaps that must be addressed to successfully implement its use in global scale carbon models.
    Type: Article , PeerReviewed
    Format: text
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  • 14
    Publication Date: 2021-01-26
    Description: Over the last decades, the Arctic Ocean has suffered a substantial decline in sea ice cover due to global warming. The impacts of these variations on primary productivity, fluxes of dissolved and particulate organic matter (OM) and turnover at the seafloor are still poorly understood. Here we focus on the characteristics and dynamics of the pool of marine dissolved OM (DOM) in surface sediments of the Arctic Ocean. To investigate spatial and temporal variations of DOM in relation to particulate OM input and benthic microbial community parameters, sediment porewater and overlying bottom water were collected from the long-term observatory HAUSGARTEN in June 2013 and 2014. The study area in the Fram Strait, which is partially covered by sea ice, was sampled along a bathymetric transect (1050–5500 m water depth), from east to west (7°0.2′ E to 5°17′ W), and from south to north (78°37’ to 79°43’ N). Molecular data on solid phase extracted DOM obtained via Fourier Transform Ion Cyclotron Resonance Mass Spectrometric analysis and a suite of bulk chemical parameters were related to benthic biogeochemical data. Our results demonstrate a close coupling between the production and input of OM from the surface ocean to the seafloor, and the concentration and composition of DOC/DOM in the deep sea. Surface porewaters collected in 2013 from shallower stations (≤1500 m water depth) in the eastern Fram Strait, had a signal of a larger and more recent input of OM (higher concentrations of phytodetritus). This was associated with higher numbers of molecular formulas, abundances of unsaturated aliphatic and N-containing formulas, in concert with higher enzymatic activity, phospholipids, total organic carbon and protein content. In contrast, porewaters collected in 2014 from deeper stations and from the West, were associated with lower OM input, and showed higher abundances of aromatic and oxygen-poor compounds. Higher OM input was also reflected in higher DOC concentrations and fluxes from the sediment into the water column. Our study demonstrates that regional and temporal variations in OM input can quickly translate into changes in the quantity and quality of surface porewater DOM, the latter substantially altered by deep-sea sediment bacteria.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 15
    Publication Date: 2021-05-05
    Description: The potential of marine dissolved organic matter (DOM) for free radical scavenging has been extensively evaluated, however, the quantitative assessment of the antioxidant potential has been recently measured for the first time. The linkage of the DOM antioxidant potential to its molecular composition has not yet been examined. Following this line, this article takes a step forward by assessing, throughout a polarity-mediated fractionation, (1) the antioxidant capacity and phenolic content and (2) the molecular characterization of DOM in a more exhaustive manner. (3) The DOM antioxidant potential and phenolic content was linked to the molecular composition of DOM, which was molecularly characterized using ultrahigh resolution Fourier transform Ion Cyclotron Resonance mass spectrometry (FT-ICR MS). Antioxidant activity and phenolic content were quantified by the free radical 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS⋅) and the Folin-Ciocalteu methods, respectively. We considered three types of different natural DOM samples: the deep North Pacific Ocean, the oligotrophic surface of the North Pacific Ocean and porewater from the sulfidic tidal flats of the Wadden Sea. Bulk porewater and its individual polarity fractions presented the highest antioxidant activity and phenolic content. DOM from the water column samples had lower antioxidant activity and phenolic content than porewater, but exceeded what it is commonly found in macroalgae, microalgae, fruits and vegetables with cosmeceutical purposes. Our values were similar to published values for terrestrial DOM. The variations in bioactivity were dependent on polarity and molecular composition. The high resolution and high mass accuracy used to determine the molecular composition of marine DOM and the chemometric and multistatistical analyses employed have allowed to distinguish molecular categories that are related to the bioactive potential. As a future perspective, we performed cytotoxicity tests with human cells and propose marine DOM as a natural ingredient for the development of cosmeceutical products.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 16
    Publication Date: 2020-05-29
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 17
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Estuarine, Coastal and Shelf Science 65 (2005): 587-600, doi:10.1016/j.ecss.2005.07.005.
    Description: Here we present the first reconstruction of changes in surface primary production during the last century from the Puyuhuapi fjord in southern Chile, using a variety of parameters (diatoms, biogenic silica, total organic carbon, chlorins, and proteins) as productivity proxies. Two sediment cores from the head and the center of the fjord were analyzed and compared to gain insights on past changes in productivity in these two different depositional environments. Higher sedimentation rates found at the head of the fjord result from the combination of a shallower water column and a restricted circulation by the occurrence of a sill. Additionally, sediment mixing depths estimated from 210Pb data suggest that suboxic conditions may dominate the bottom water and the sediment-water interface in this location. Productivity of the Puyuhuapi fjord during the last century was characterized by a constant increase from the late 19th century to the early 1980s, then decreased until the late-1990s, and then rose again to present-day values. The influence of rainfall on productivity was most noticeable during periods of low rainfall, which coincided with decreased overall productivity within the Puyuhuapi fjord. Simultaneous variations in productivity and rainfall in the study area suggest that marine productivity could respond to atmospheric-oceanic interactions at a local scale. At a regional scale, marine productivity of the area may be related to other large-scale processes such as the El Niño Southern Oscillation.
    Description: We are grateful to the Ministerio de Hacienda de Chile (Chilean Ministry of Treasury) and the National Oceanographic Committee (CONA) for financial support to carry out the Cimar-7 Fiordo Program (Grant C7F 01-10 to Silvio Pantoja), the FONDAP-COPAS Center, and Grant 200.031.085-1 (UdeC) for financial support. Sepúlveda was funded by a scholarship from the Graduate School of the University of Concepción and by the FONDAP-COPAS Center. Additional support was given by Fundación Andes through the Woods Hole Oceanographic Institution/University of Concepción agreement.
    Keywords: Paleoproductivity ; Organic matter ; Fjords ; Chile
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: 603977 bytes
    Format: application/pdf
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  • 18
    Publication Date: 2022-10-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wagner, S., Schubotz, F., Kaiser, K., Hallmann, C., Waska, H., Rossel, P. E., Hansmann, R., Elvert, M., Middelburg, J. J., Engel, A., Blattmann, T. M., Catala, T. S., Lennartz, S. T., Gomez-Saez, G., V., Pantoja-Gutierrez, S., Bao, R., & Galy, V. Soothsaying DOM: A current perspective on the future of oceanic dissolved organic carbon. Frontiers in Marine Science, 7, (2020): 341, doi:10.3389/fmars.2020.00341.
    Description: The vast majority of freshly produced oceanic dissolved organic carbon (DOC) is derived from marine phytoplankton, then rapidly recycled by heterotrophic microbes. A small fraction of this DOC survives long enough to be routed to the interior ocean, which houses the largest and oldest DOC reservoir. DOC reactivity depends upon its intrinsic chemical composition and extrinsic environmental conditions. Therefore, recalcitrance is an emergent property of DOC that is analytically difficult to constrain. New isotopic techniques that track the flow of carbon through individual organic molecules show promise in unveiling specific biosynthetic or degradation pathways that control the metabolic turnover of DOC and its accumulation in the deep ocean. However, a multivariate approach is required to constrain current carbon fluxes so that we may better predict how the cycling of oceanic DOC will be altered with continued climate change. Ocean warming, acidification, and oxygen depletion may upset the balance between the primary production and heterotrophic reworking of DOC, thus modifying the amount and/or composition of recalcitrant DOC. Climate change and anthropogenic activities may enhance mobilization of terrestrial DOC and/or stimulate DOC production in coastal waters, but it is unclear how this would affect the flux of DOC to the open ocean. Here, we assess current knowledge on the oceanic DOC cycle and identify research gaps that must be addressed to successfully implement its use in global scale carbon models.
    Description: This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 422798570. The Hanse-Wissenschaftskolleg and the Geochemical Society provided funding for the conference. Additional support was provided by the National Science Foundation OCE #1756812 to SW. TB acknowledges funding from ETH Zürich and JAMSTEC. JM was supported by the Netherlands Earth System Science Centre. SP-G was funded by COPAS Sur-Austral (CONICYT PIA APOYO CCTE AFB170006). GG-S acknowledges funding from DFG, DI 842/6-1.
    Keywords: Dissolved organic carbon ; Global carbon cycle ; Recalcitrance ; Isotopic probing ; Climate change
    Repository Name: Woods Hole Open Access Server
    Type: Article
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