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  • Artikel  (6)
  • OceanRep
  • Canada Basin  (2)
  • Plant wax lipids  (2)
  • Sediment transport  (2)
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  • Artikel  (6)
  • OceanRep
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  • 1
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    Lateral organic carbon supply to the deep Canada Basin (2010)
    American Geophysical Union
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L11607, doi:10.1029/2008GL034271.
    Beschreibung: Understanding the processes driving the carbon cycle in the Arctic Ocean is important for assessing the impacts of the predicted rapid and amplified climate change in this region. We analyzed settling particle samples intercepted by a time-series sediment trap deployed in the abyssal Canada Basin (at 3067 m) in order to examine carbon export to the deep Arctic Ocean. Strikingly old radiocarbon ages (apparent mean 14C age = ∼1900 years) of the organic carbon, abundant lithogenic material (∼80%), and mass flux variations temporally decoupled from the cycle of primary productivity in overlying surface waters together suggest that, unlike other ocean basins, the majority of the particulate organic carbon entering the deep Canada Basin is supplied from the surrounding margins.
    Beschreibung: This research was funded by the NSF Ocean Sciences Division (Chemical Oceanography program) and NSF Office of Polar Programs, Office of Naval Research, as well as the Ocean and Climate Change Institute and Arctic Research Initiative at the Woods Hole Oceanographic Institution.
    Schlagwort(e): POC ; Lateral transport ; Canada Basin
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 2
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    Rapid lateral particle transport in the Argentine Basin : molecular C-14 and Th-230(xs) evidence (2006)
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Elsevier B.V., 2006. 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 Deep Sea Research Part I: Oceanographic Research Papers 53 (2006): 1224-1243, doi:10.1016/j.dsr.2006.05.005.
    Beschreibung: Recent studies have revealed that lateral transport and focusing of particles strongly influences the depositional patterns of organic matter in marine sediments. Transport can occur in the water column prior to initial deposition or following sediment re-suspension. In both cases, fine-grained particles and organic-rich aggregates are more susceptible to lateral transport than coarse-grained particles (e.g. foraminiferal tests) because of the slower sinking velocities of the former. This may lead to spatial and, in the case of redistribution of resuspended sediments, temporal decoupling of organic matter from coarser sediment constituents. Prior studies from the Argentine Basin have yielded evidence that suspended particles are displaced significant distances (100 - 1000 km) northward and downslope by strong surface and/or bottom currents. These transport processes result in anomalously cold alkenone-derived sea surface temperature (SST) estimates (up to 6°C colder than measured SST) and in the presence of frustules of Antarctic diatom species in surface sediments fromthis area. Here we examine advective transport processes through combined measurements of compound-specific radiocarbon ages of marine phytoplankton derived biomarkers (alkenones) from core-tops and excess 230Th (230Thxs)-derived focusing factors for late Holocene sediments from the Argentine Basin. On the continental slope, we observe 230Thxs-based focusing factors of 1.4 to 3.2 at sites where alkenone-based SST estimates were 4–6°C colder than measured values. In contrast, alkenone radiocarbon data suggest coeval deposition of marine biomarkers and planktic foraminifera, as alkenones in core-tops were younger than, or similar in age to, foraminifera. We therefore infer that the transport processes leading to the lateral displacement of these sediment components are rapid, and hence probably occur in the upper water column (〈1500 m).
    Beschreibung: This work was funded by NSF grant #OCE-0327405 and a WHOI-NOSAMS postdoctoral scholarship to GM, and by support from NSF and the Gary Comer Science and Education Foundation to JFM.
    Schlagwort(e): Sediment transport ; Radiocarbon dating ; Sea-surface temperatures ; Core-top sediments ; South Atlantic Ocean ; Argentine and Brazil Basins ; Brazil-Malvinas Confluence
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
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  • 3
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    14C and 13C characteristics of higher plant biomarkers in Washington margin surface sediments (2013)
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 105 (2013): 14-30, doi:10.1016/j.gca.2012.11.034.
    Beschreibung: Plant wax lipids and lignin phenols are the two most common classes of molecular markers that are used to trace vascular plant-derived OM in the marine environment. However, their 13C and 14C compositions have not been directly compared, which can be used to constrain the flux and attenuation of terrestrial carbon in marine environment. In this study, we describe a revised method of isolating individual lignin phenols from complex sedimentary matrices for 14C analysis using high pressure liquid chromatography (HPLC) and compare this approach to a method utilizing preparative capillary gas chromatography (PCGC). We then examine in detail the 13C and 14C compositions of plant wax lipids and lignin phenols in sediments from the inner and mid shelf of the Washington margin that are influenced by discharge of the Columbia River. Plant wax lipids (including n-alkanes, n-alkanoic (fatty) acids, n-alkanols, and n-aldehydes) displayed significant variability in both δ13C (-28.3 to -37.5 ‰) and ∆14C values (-204 to +2 ‰), suggesting varied inputs and/or continental storage and transport histories. In contrast, lignin phenols exhibited similar δ13C values (between -30 to -34 ‰) and a relatively narrow range of ∆14C values (-45 to -150 ‰; HPLC-based mesurement) that were similar to, or younger than, bulk OM (-195 to -137 ‰). Moreover, lignin phenol 14C age correlated with the degradation characteristics of this terrestrial biopolymer in that vanillyl phenols were on average ~500 years older than syringyl and cinnamyl phenols that degrade faster in soils and sediments. The isotopic characteristics, abundance, and distribution of lignin phenols in sediments suggest that they serve as promising tracers of recently biosynthesized terrestrial OM during supply to, and dispersal within the marine environment. Lignin phenol 14C measurements may also provide useful constraints on the vascular plant end member in isotopic mixing models for carbon source apportionment, and for interpretation of sedimentary records of past vegetation dynamics. Key words: 14C and 13C composition, radiocarbon age, plant wax lipids, lignin phenols, Washington margin, marine carbon cycling, terrestrial organic matter
    Beschreibung: Grants OCE-9907129, OCE-0137005, and OCE-0526268 (to TIE) from the National Science Foundation (NSF) supported this research.
    Schlagwort(e): 14C and 13C composition ; Radiocarbon age ; Plant wax lipids ; Lignin phenols ; Washington margin ; Marine carbon cycling ; Terrestrial organic matter
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  • 4
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    Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic : 14C characteristics of sedimentary carbon components and their environmental controls (2016)
    John Wiley & Sons
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 29 (2015): 1855–1873, doi:10.1002/2015GB005204.
    Beschreibung: Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these “old” terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.
    Beschreibung: Chinese National Key Development Program for Basic Research Grant Numbers: 2014CB954003, 2015CB954201; Knut and Alice Wallenberg Foundation; Headquarters of the Russian Academy of Sciences; Swedish Research Council; US National Oceanic and Atmospheric Administration; Russian Foundation of Basic Research Grant Numbers: (13-05-12028, 13-05-12041; Swedish Polar Research Secretariat; Nordic Council of Ministers; Government of the Russian Federation Grant Number: 2013-220-04-157; Swiss National Science foundation. Grant Number: (200021_140850 US National Science Foundation (NSF) Grant Numbers: OCE-9907129, OCE-0137005, OCE-0526268; Stanley Watson Chair for Excellence in Oceanography Grant Number: 825.10.022; ETH Zürich; NWO Rubicon; Veni Grant Number: 863.12.004; UK NERC Grant Number: NE/I024798/1; NSF. Grant Numbers: 0436118, 0732555, 1107774
    Beschreibung: 2016-05-02
    Schlagwort(e): Compound-specific radiocarbon analysis ; Terrestrial carbon markers ; Pan-arctic rivers ; Diacids ; Lignin ; Plant wax lipids
    Repository-Name: Woods Hole Open Access Server
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  • 5
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    Aging of marine organic matter during cross-shelf lateral transport in the Benguela upwelling system revealed by compound-specific radiocarbon dating (2010)
    American Geophysical Union
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q09004, doi:10.1029/2007GC001603.
    Beschreibung: Organic matter accumulation and burial on the Namibian shelf and upper slope are spatially heterogeneous and strongly controlled by lateral transport in subsurface nepheloid layers. Much of the material deposited in depo-centers on the slope ultimately derives from the shelf. Supply of organic matter from the shelf involves selective transport of organic matter. We studied these selective transport processes by analyzing the radiocarbon content of co-occurring sediment fractions. Here we present radiocarbon data for total organic carbon as well as three tracers of surface ocean productivity (phytoplankton-derived alkenones, membrane lipids of pelagic crenarchaeota (crenarchaeol), and calcareous microfossils of planktic foraminifera) in core-top and near-surface sediment samples. The samples were collected on the Namibian margin along a shelf-slope transect (85 to 1040 m) at 24°S and from the upper slope depo-center at 25.5°S. In core-top sediments, alkenone ages gradually increased from modern to 3490 radiocarbon years with distance from shore and with water depth. Crenarchaeol, while younger than alkenones, also increased in age with distance offshore. It was concluded that the observed ages were a consequence of cross-shelf transport and associated aging of organic matter. Radiocarbon ages of preserved lipid biomarkers in sediments thus at least partially depend on the relative amount of laterally supplied, pre-aged material present in a sample, highlighting the importance of nepheloid transport for the sedimentation of organic matter over the Namibian margin.
    Beschreibung: This work was funded by NSF grant OCE- 0327405 to T.I.E. and by a Spinoza grant to J.S.S.D. from NWO.
    Schlagwort(e): Compound-specific radiocarbon dating ; Sediment transport
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  • 6
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    Temporal and spatial variability of particle transport in the deep Arctic Canada Basin (2015)
    John Wiley & Sons
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    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 2784–2799, doi:10.1002/2014JC010643.
    Beschreibung: To better understand the current carbon cycle and potentially detect its change in the rapidly changing Arctic Ocean, we examined sinking particles collected quasi-continuously over a period of 7 years (2004–2011) by bottom-tethered sediment trap moorings in the central Canada Basin. Total mass flux was very low (〈100 mg m−2 d−1) at all sites and was temporally decoupled from the cycle of primary production in surface waters. Extremely low radiocarbon contents of particulate organic carbon and high aluminum contents in sinking particles reveal high contributions of resuspended sediment to total sinking particle flux in the deep Canada Basin. Station A (75°N, 150°W) in the southwest quadrant of the Canada Basin is most strongly influenced while Station C (77°N, 140°W) in the northeast quadrant is least influenced by lateral particle supply based on radiocarbon content and Al concentration. The results at Station A, where three sediment traps were deployed at different depths, imply that the most likely mode of lateral particle transport was as thick clouds of enhanced particle concentration extending well above the seafloor. At present, only 1%–2% of the low levels of new production in Canada Basin surface waters reaches the interior basin. Lateral POC supply therefore appears to be the major source of organic matter to the interior basin. However, ongoing changes to surface ocean boundary conditions may influence both lateral and vertical supply of particulate material to the deep Canada Basin.
    Beschreibung: This research was funded by the NSF Division of Polar Programs (ARC-0909377), the Ocean and Climate Change Institute of Woods Hole Oceanographic Institution, and ETH Zürich. J.H. and M.K. were partly supported by the National Research Foundation of Korea grant funded by the Korean Government (2011–0013629).
    Schlagwort(e): Canada Basin ; Particulate organic carbon ; Lateral supply ; Radiocarbon ; Carbon cycle
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