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  • Artikel  (17)
  • American Geophysical Union  (15)
  • Ecological Society of America  (2)
  • 2020-2023  (17)
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  • 2022  (17)
  • 1
    Publikationsdatum: 2022-10-27
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Loescher, H., Vargas, R., Mirtl, M., Morris, B., Pauw, J., Yu, X., Kutsch, W., Mabee, P., Tang, J., Ruddell, B., Pulsifer, P., Bäck, J., Zacharias, S., Grant, M., Feig, G., Zheng, L., Waldmann, C., & Genazzio, M. Building a global ecosystem research infrastructure to address global grand challenges for macrosystem ecology. Earth’s Future, 10(5), (2022): e2020EF001696, https://doi.org/10.1029/2020ef001696.
    Beschreibung: The development of several large-, “continental”-scale ecosystem research infrastructures over recent decades has provided a unique opportunity in the history of ecological science. The Global Ecosystem Research Infrastructure (GERI) is an integrated network of analogous, but independent, site-based ecosystem research infrastructures (ERI) dedicated to better understand the function and change of indicator ecosystems across global biomes. Bringing together these ERIs, harmonizing their respective data and reducing uncertainties enables broader cross-continental ecological research. It will also enhance the research community capabilities to address current and anticipate future global scale ecological challenges. Moreover, increasing the international capabilities of these ERIs goes beyond their original design intent, and is an unexpected added value of these large national investments. Here, we identify specific global grand challenge areas and research trends to advance the ecological frontiers across continents that can be addressed through the federation of these cross-continental-scale ERIs.
    Beschreibung: This manuscript is in part the product of several workshops and ongoing GERI development. The first workshop was the Terrestrial Ecosystem Research Network (TERN) sponsored and entitled: “Towards a Global Ecosystem Observatory”, 5–7 March 2017, University of Queensland, Brisbane Australia. Another workshop was sponsored by Chinese Academy of Sciences (CAS) and entitled: “Global Integrated Research Infrastructure component in Next Generation ILTER”, 17–20 April, 2018, South China Botanical Garden, Zhaoqing, Guangdong Province, China. The National Science Foundation (NSF) supported two workshops. The first was entitled: ‘Building a Global Ecological Understanding’ held at the University of Delaware, Newark Delaware, 3–6 June, 2016 (NSF 1347883) and the second entitled: “Global Environmental Research Infrastructure (GERI) Planning Workshop”, held at NEON HQ, Boulder Colorado, 25–27 June 2019 (NSF 1917180). The authors wish to thank the workshop attendees for their thoughtful contributions. NEON is a project sponsored by the NSF and managed under cooperative support agreement (DBI-1029808) to Battelle.
    Schlagwort(e): Environmental research infrastructure ; Macrosystem science ; Interoperability ; Societal benefit ; New capabilities ; Federating infrastructure
    Repository-Name: Woods Hole Open Access Server
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  • 2
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Horner, T. J., Little, S. H., Conway, T. M., Farmer, J. R., Hertzberg, J. E., Janssen, D. J., Lough, A. J. M., McKay, J. L., Tessin, A., Galer, S. J. G., Jaccard, S. L., Lacan, F., Paytan, A., Wuttig, K., & GEOTRACES–PAGES Biological Productivity Working Group Members (2021). Bioactive trace metals and their isotopes as paleoproductivity proxies: an assessment using GEOTRACES-era data. Global Biogeochemical Cycles, 35(11), e2020GB006814. https://doi.org/10.1029/2020GB006814.
    Beschreibung: Phytoplankton productivity and export sequester climatically significant quantities of atmospheric carbon dioxide as particulate organic carbon through a suite of processes termed the biological pump. Constraining how the biological pump operated in the past is important for understanding past atmospheric carbon dioxide concentrations and Earth's climate history. However, reconstructing the history of the biological pump requires proxies. Due to their intimate association with biological processes, several bioactive trace metals and their isotopes are potential proxies for past phytoplankton productivity, including iron, zinc, copper, cadmium, molybdenum, barium, nickel, chromium, and silver. Here, we review the oceanic distributions, driving processes, and depositional archives for these nine metals and their isotopes based on GEOTRACES-era datasets. We offer an assessment of the overall maturity of each isotope system to serve as a proxy for diagnosing aspects of past ocean productivity and identify priorities for future research. This assessment reveals that cadmium, barium, nickel, and chromium isotopes offer the most promise as tracers of paleoproductivity, whereas iron, zinc, copper, and molybdenum do not. Too little is known about silver to make a confident determination. Intriguingly, the trace metals that are least sensitive to productivity may be used to track other aspects of ocean chemistry, such as nutrient sources, particle scavenging, organic complexation, and ocean redox state. These complementary sensitivities suggest new opportunities for combining perspectives from multiple proxies that will ultimately enable painting a more complete picture of marine paleoproductivity, biogeochemical cycles, and Earth's climate history.
    Beschreibung: T. J. Horner acknowledges support from NSF; S. H. Little from the UK Natural Environment Research Council (NE/P018181/1); T. M. Conway from the University of South Florida; and, J. R. Farmer from the Max Planck Society, the Tuttle Fund of the Department of Geosciences of Princeton University, the Grand Challenges Program of the Princeton Environmental Institute, and the Andlinger Center for Energy and the Environment of Princeton University.
    Schlagwort(e): Biological pump ; Marine chemistry ; Biogeochemical cycles ; Micronutrients ; Phytoplankton ; Paleoceanography
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  • 3
    Publikationsdatum: 2022-10-27
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rastetter, E., Kwiatkowski, B., Kicklighter, D., Plotkin, A., Genet, H., Nippert, J., O’Keefe, K., Perakis, S., Porder, S., Roley, S., Ruess, R., Thompson, J., Wieder, W., Wilcox, K., & Yanai, R. N and P constrain C in ecosystems under climate change: role of nutrient redistribution, accumulation, and stoichiometry. Ecological Applications, (2022): e2684, https://doi.org/10.1002/eap.2684.
    Beschreibung: We use the Multiple Element Limitation (MEL) model to examine responses of 12 ecosystems to elevated carbon dioxide (CO2), warming, and 20% decreases or increases in precipitation. Ecosystems respond synergistically to elevated CO2, warming, and decreased precipitation combined because higher water-use efficiency with elevated CO2 and higher fertility with warming compensate for responses to drought. Response to elevated CO2, warming, and increased precipitation combined is additive. We analyze changes in ecosystem carbon (C) based on four nitrogen (N) and four phosphorus (P) attribution factors: (1) changes in total ecosystem N and P, (2) changes in N and P distribution between vegetation and soil, (3) changes in vegetation C:N and C:P ratios, and (4) changes in soil C:N and C:P ratios. In the combined CO2 and climate change simulations, all ecosystems gain C. The contributions of these four attribution factors to changes in ecosystem C storage varies among ecosystems because of differences in the initial distributions of N and P between vegetation and soil and the openness of the ecosystem N and P cycles. The net transfer of N and P from soil to vegetation dominates the C response of forests. For tundra and grasslands, the C gain is also associated with increased soil C:N and C:P. In ecosystems with symbiotic N fixation, C gains resulted from N accumulation. Because of differences in N versus P cycle openness and the distribution of organic matter between vegetation and soil, changes in the N and P attribution factors do not always parallel one another. Differences among ecosystems in C-nutrient interactions and the amount of woody biomass interact to shape ecosystem C sequestration under simulated global change. We suggest that future studies quantify the openness of the N and P cycles and changes in the distribution of C, N, and P among ecosystem components, which currently limit understanding of nutrient effects on C sequestration and responses to elevated CO2 and climate change.
    Beschreibung: This material is based on work supported by the National Science Foundation under Grant No. 1651722 as well through the NSF LTER Program 1637459, 2220863 (ARC), 1637686 (NWT), 1832042 (KBS), 2025849 (KNZ), 1636476 (BNZ), 1637685 (HBR), 1832210 (HFR), 2025755 (AND). We also acknowledge NSF grants 1637653 and 1754126 (INCyTE RCN), and DOE grant DESC0019037. We also acknowledge support through the USDA Forest Service Hubbard Brook Experimental Forest, North Woodstock, New Hampshie (USDA NIFA 2019-67019-29464) and Pacific Northwest Research Station, Corvallis, Oregon.
    Schlagwort(e): Carbon dioxide fertilization ; Carbon sequestration ; Carbon-nitrogen interactions ; Carbon-phosphorus interactions ; Climate change ; Long-term ecological research (LTER) ; Nitrogen cycle ; Phosphorus cycle ; Terrestrial ecosystem stoichiometry
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  • 4
    Publikationsdatum: 2022-10-27
    Beschreibung: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(10),(2021): e2021JB022050, https://doi.org/10.1029/2021JB022050.
    Beschreibung: On-fault earthquake magnitude distributions are calculated for northern Caribbean faults using estimates of fault slip and regional seismicity parameters. Integer programming, a combinatorial optimization method, is used to determine the optimal spatial arrangement of earthquakes sampled from a truncated Gutenberg-Richter distribution that minimizes the global misfit in slip rates on a complex fault system. Slip rates and their uncertainty on major faults are derived from a previously published GPS block model for the region, with fault traces determined from offshore geophysical mapping and previously published onshore studies. The optimal spatial arrangement of the sampled earthquakes is compared with the 500-year history of earthquake observations. Rupture segmentation of the subduction interface along the Hispaniola-Puerto Rico Trench (PRT) fault and seismic coupling on the PRT fault appear to exert the primary control over this spatial arrangement. Introducing a rupture barrier for the Hispaniola-PRT fault northwest of Mona Passage, based on geophysical and seismicity observations, and assigning a low slip rate of 2 mm/yr on the PRT fault are most consistent with historical earthquakes in the region. The addition of low slip-rate secondary faults as well as segmentation of the Hispaniola and Septentrional strike-slip fault improves the consistency with historical seismicity. An important observation from the modeling is that varying the slip rate on the PRT fault and different segmentation scenarios result in significant changes to the optimal magnitude distribution on faults farther away. In general, optimal on-fault magnitude distributions are more complex and inter-dependent than is typically assumed in probabilistic seismic hazard analysis and probabilistic tsunami hazard analysis.
    Beschreibung: Funding for this study is from the U.S. Geological Survey Coastal and Marine Hazards and Resources Program.
    Beschreibung: 2022-04-11
    Schlagwort(e): Northern Caribbean ; Rupture forecast ; Combinatorial optimization ; Integer programming
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  • 5
    Publikationsdatum: 2022-10-27
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Blagden, M., Harrison, J. L., Minocha, R., Sanders-DeMott, R., Long, S., & Templer, P. H. Climate change influences foliar nutrition and metabolism of red maple (Acer rubrum) trees in a northern hardwood forest. Ecosphere, 13(2), (2022): e03859. https://doi.org/10.1002/ecs2.3859.
    Beschreibung: Mean annual air temperatures are projected to increase, while the winter snowpack is expected to shrink in depth and duration for many mid- and high-latitude temperate forest ecosystems over the next several decades. Together, these changes will lead to warmer growing season soil temperatures and an increased frequency of soil freeze–thaw cycles (FTCs) in winter. We took advantage of the Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire, USA, to determine how these changes in soil temperature affect foliar nitrogen (N) and carbon metabolism of red maple (Acer rubrum) trees in 2015 and 2017. Earlier work from this study revealed a similar increase in foliar N concentrations with growing season soil warming, with or without the occurrence of soil FTCs in winter. However, these changes in soil warming could differentially affect the availability of cellular nutrients, concentrations of primary and secondary metabolites, and the rates of photosynthesis that are all responsive to climate change. We found that foliar concentrations of phosphorus (P), potassium (K), N, spermine (a polyamine), amino acids (alanine, histidine, and phenylalanine), chlorophyll, carotenoids, sucrose, and rates of photosynthesis increased with growing season soil warming. Despite similar concentrations of foliar N with soil warming with and without soil FTCs in winter, winter soil FTCs affected other foliar metabolic responses. The combination of growing season soil warming and winter soil FTCs led to increased concentrations of two polyamines (putrescine and spermine) and amino acids (alanine, proline, aspartic acid, γ-aminobutyric acid, valine, leucine, and isoleucine). Treatment-specific metabolic changes indicated that while responses to growing season warming were more connected to their role as growth modulators, soil warming + FTC treatment-related effects revealed their dual role in growth and stress tolerance. Together, the results of this study demonstrate that growing season soil warming has multiple positive effects on foliar N and cellular metabolism in trees and that some of these foliar responses are further modified by the addition of stress from winter soil FTCs.
    Beschreibung: This research was supported by an NSF Long Term Ecological Research (LTER) Grant to Hubbard Brook (NSF 1114804 and 1637685) and an NSF CAREER grant to PHT (NSF DEB1149929). RSD was supported by NSF DGE0947950, a Boston University (BU) Dean's Fellowship, and the BU Program in Biogeoscience. Jamie Harrison was supported by a BU Dean's Fellowship. Megan Blagden was supported by a BU Undergraduate Research Opportunity Program fellowship. This manuscript is a contribution to the Hubbard Brook Ecosystem Study. Hubbard Brook is part of the LTER network, which is supported by the NSF.
    Schlagwort(e): Amino acids ; Chlorophyll ; HPLC ; Inorganic nutrients ; Metabolism ; Photosynthesis ; Polyamines ; Soil freeze-thaw cycles ; Soil warming ; Stress ; Sugars
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  • 6
    Publikationsdatum: 2022-10-27
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zeigler, S. L., Gutierrez, B. T., Lentz, E. E., Plant, N. G., Sturdivant, E. J., & Doran, K. S. Predicted sea-level rise-driven biogeomorphological changes on Fire Island, New York: implications for people and plovers. Earth’s Future, 10(4), (2022): e2021EF002436, https://doi.org/10.1029/2021EF002436.
    Beschreibung: Forecasting biogeomorphological conditions for barrier islands is critical for informing sea-level rise (SLR) planning, including management of coastal development and ecosystems. We combined five probabilistic models to predict SLR-driven changes and their implications on Fire Island, New York, by 2050. We predicted barrier island biogeomorphological conditions, dynamic landcover response, piping plover (Charadrius melodus) habitat availability, and probability of storm overwash under three scenarios of shoreline change (SLC) and compared results to observed 2014/2015 conditions. Scenarios assumed increasing rates of mean SLC from 0 to 4.71 m erosion per year. We observed uncertainty in several morphological predictions (e.g., beach width, dune height), suggesting decreasing confidence that Fire Island will evolve in response to SLR as it has in the past. Where most likely conditions could be determined, models predicted that Fire Island would become flatter, narrower, and more overwash-prone with increasing rates of SLC. Beach ecosystems were predicted to respond dynamically to SLR and migrate with the shoreline, while marshes lost the most area of any landcover type compared to 2014/2015 conditions. Such morphological changes may lead to increased flooding or breaching with coastal storms. However—although modest declines in piping plover habitat were observed with SLC—the dynamic response of beaches, flatter topography, and increased likelihood of overwash suggest storms could promote suitable conditions for nesting piping plovers above what our geomorphology models predict. Therefore, Fire Island may offer a conservation opportunity for coastal species that rely on early successional beach environments if natural overwash processes are encouraged.
    Beschreibung: Funding for this work was provided by the U.S. Geological Survey's Coastal and Marine Hazards and Resources Program, with supplemental funding through the Disaster Relief Act.
    Schlagwort(e): Sea level rise ; Erosion ; Coastal habitats ; Barrier island ; Shorebirds
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  • 7
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Davila, X., Gebbie, G., Brakstad, A., Lauvset, S. K., McDonagh, E. L., Schwinger, J., & Olsen, A. How Is the ocean anthropogenic carbon reservoir filled? Global Biogeochemical Cycles, 36(5), (2022): e2021GB007055, https://doi.org/10.1029/2021GB007055.
    Beschreibung: About a quarter of the total anthropogenic CO2 emissions during the industrial era has been absorbed by the ocean. The rate limiting step for this uptake is the transport of the anthropogenic carbon (Cant) from the ocean mixed layer where it is absorbed to the interior ocean where it is stored. While it is generally known that deep water formation sites are important for vertical carbon transport, the exact magnitude of the fluxes across the base of the mixed layer in different regions is uncertain. Here, we determine where, when, and how much Cant has been injected across the mixed-layer base and into the interior ocean since the start of the industrialized era. We do this by combining a transport matrix derived from observations with a time-evolving boundary condition obtained from already published estimates of ocean Cant. Our results show that most of the Cant stored below the mixed layer are injected in the subtropics (40.1%) and the Southern Ocean (36.0%), while the Subpolar North Atlantic has the largest fluxes. The Subpolar North Atlantic is also the most important region for injecting Cant into the deep ocean with 81.6% of the Cant reaching depths greater than 1,000 m. The subtropics, on the other hand, have been the most efficient in transporting Cant across the mixed-layer base per volume of water ventilated. This study shows how the oceanic Cant uptake relies on vertical transports in a few oceanic regions and sheds light on the pathways that fill the ocean Cant reservoir.
    Beschreibung: X. Davila was supported by a PhD research fellowship from the University of Bergen. G. Gebbie was supported by U.S. NSF Grant 88075300. A. Brakstad was supported by the Trond Mohn Foundation under grant agreement BFS2016REK01. E. L. McDonagh was supported by UKRI grants Atlantic Biogeochemical fluxes (ref no. NE/M005046/2) and TICTOC:Transient tracer-based Investigation of Circulation and Thermal Ocean Change (ref no. NE/P019293/2). A. Olsen and S. K. Lauvset appreciate support from the Research Council of Norway (ICOS-Norway, project number 245972). J. Schwinger acknowledges support by the Research Council of Norway through project INES (project number 270061). Supercomputer time and storage resources were provided by the The Norwegian e-infrastructure for Research Education (UNINETT Sigma2, projects nn2980k and ns2980k).
    Schlagwort(e): Anthropogenic carbon ; Transport matrix ; Mixed-layer ; Observations ; Fluxes
    Repository-Name: Woods Hole Open Access Server
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  • 8
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hage, S., Galy, V., Cartigny, M., Heerema, C., Heijnen, M., Acikalin, S., Clare, M., Giesbrecht, I., Gröcke, D., Hendry, A., Hilton, R., Hubbard, S., Hunt, J., Lintern, D., McGhee, C., Parsons, D., Pope, E., Stacey, C., Sumner, E., Tank, S., & Talling, P. Turbidity currents can dictate organic carbon fluxes across river‐fed fjords: an example from Bute Inlet (BC, Canada). Journal of Geophysical Research: Biogeosciences, 127(6), (2022): e2022JG006824, https://doi.org/10.1029/2022jg006824.
    Beschreibung: The delivery and burial of terrestrial particulate organic carbon (OC) in marine sediments is important to quantify, because this OC is a food resource for benthic communities, and if buried it may lower the concentrations of atmospheric CO2 over geologic timescales. Analysis of sediment cores has previously shown that fjords are hotspots for OC burial. Fjords can contain complex networks of submarine channels formed by seafloor sediment flows, called turbidity currents. However, the burial efficiency and distribution of OC by turbidity currents in river-fed fjords had not been investigated previously. Here, we determine OC distribution and burial efficiency across a turbidity current system within Bute Inlet, a fjord in western Canada. We show that 62% ± 10% of the OC supplied by the two river sources is buried across the fjord surficial (30–200 cm) sediment. The sandy subenvironments (channel and lobe) contain 63% ± 14% of the annual terrestrial OC burial in the fjord. In contrast, the muddy subenvironments (overbank and distal basin) contain the remaining 37% ± 14%. OC in the channel, lobe, and overbank exclusively comprises terrestrial OC sourced from rivers. When normalized by the fjord’s surface area, at least 3 times more terrestrial OC is buried in Bute Inlet, compared to the muddy parts of other fjords previously studied. Although the long-term (〉100 years) preservation of this OC is still to be fully understood, turbidity currents in fjords appear to be efficient at storing OC supplied by rivers in their near-surface deposits.
    Beschreibung: S.H. acknowledges funding by the IAS postgraduate grant scheme, a Research Development funds offered by Durham University, and the NOCS/WHOI exchange program. S.H. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 899546. The field campaign and geochemical analyses were supported by Natural Environment Research Council grants NE/M007138/1, NE/W30601/1, NE/N012798/1, NE/K011480/1 and NE/M017540/1. M.J.B.C. was funded by a Royal Society Research Fellowship (DHF\R1\180166). M.A.C. was supported by the U.K. National Capability NERC CLASS program (NE/R015953/1) and NERC grants (NE/P009190/1 and NE/P005780/1). C.J.H. and M.S.H. were funded by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 721403 - ITN SLATE. E.L.P. was supported by a Leverhulme Early Career Fellowship (ECF-2018-267).
    Schlagwort(e): Fjords ; Organic carbon ; Sediment ; Submarine channel ; Carbon burial ; Rivers
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  • 9
    Publikationsdatum: 2022-05-27
    Beschreibung: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 126(10),(2021): e2021JC017375.,https://doi.org/10.1029/2021JC017375.
    Beschreibung: The Deep Water Horizon oil spill dramatically impacted the Gulf of Mexico from the seafloor to the surface. While dispersion of contaminants at the surface has been extensively studied, little is known about deep water dispersion properties. This study describes the results of the Deep Water Dispersion Experiment (DWDE), which consisted of the release of surface drifters and acoustically tracked RAFOS floats drifting at 300 and 1,500 dbar in the Gulf of Mexico. We show that surface diffusivity is elevated and decreases with depth: on average, diffusivity at 1,500 dbar is 5 times smaller than at the surface, suggesting that the dispersion of contaminants at depth is a significantly slower process than at the surface. This study also examines the turbulent regimes driving the dispersion, although conflicting evidences and large uncertainties do not allow definitive conclusions. At all depths, while the growth of dispersion and kurtosis with time supports the possibility of an exponential regime at very short time scales, indicating that early dispersion is nonlocal, finite size Lyapunov exponents support the hypothesis of local dispersion, suggesting that eddies of size comparable to the initial separation (6 km), may dominate the early dispersion. At longer time scales, the quadratic growth of dispersion is indicative of a ballistic regime, where a mean shear flow would be the dominating process. Examination of the along- and across-bathymetry components of float velocities supports the idea that boundary currents could be the source for this shear dispersion.
    Beschreibung: This research has been funded by the Mexican National Council for Science and Technology - Mexican Ministry of Energy - Hydrocarbon Fund, project 201441. This is a contribution of the Gulf of Mexico Research Consortium (CIGoM).
    Beschreibung: 2022-03-18
    Schlagwort(e): Lagrangian experiment ; turbulence ; RAFOS ; relative dispersion ; Gulf of Mexico ; Deep Water Dispersion
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  • 10
    Publikationsdatum: 2022-05-27
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hines, S. K. V., Bolge, L., Goldstein, S. L., Charles, C. D., Hall, I. R., & Hemming, S. R. Little change in ice age water mass structure from Cape Basin benthic neodymium and carbon isotopes. Paleoceanography and Paleoclimatology, 36(11), (2021): e2021PA004281, https://doi.org/10.1029/2021PA004281.
    Beschreibung: A common conception of the deep ocean during ice age episodes is that the upper circulation cell in the Atlantic was shoaled at the Last Glacial Maximum compared to today, and that this configuration facilitated enhanced carbon storage in the deep ocean, contributing to glacial CO2 draw-down. Here, we test this notion in the far South Atlantic, investigating changes in glacial circulation structure using paired neodymium and benthic carbon isotope measurements from International Ocean Discovery Program Site U1479, at 2,615 m water depth in the Cape Basin. We infer changes in circulation structure across the last glacial cycle by aligning our site with other existing carbon and neodymium isotope records from the Cape Basin, examining vertical isotope gradients, while determining the relative timing of inferred circulation changes at different depths. We find that Site U1479 had the most negative neodymium isotopic composition across the last glacial cycle among the analyzed sites, indicating that this depth was most strongly influenced by North Atlantic Deep Water (NADW) in both interglacial and glacial intervals. This observation precludes a hypothesized dramatic shoaling of NADW above ∼2,000 m. Our evidence, however, indicates greater stratification between mid-depth and abyssal sites throughout the last glacial cycle, conditions that developed in Marine Isotope Stage 5. These conditions still may have contributed to glacial carbon storage in the deep ocean, despite little change in the mid-depth ocean structure.
    Beschreibung: This work was supported by NSF grant OCE-1831415 (S. K. V. Hines, S. L. Goldstein., S. R. Hemming.).
    Beschreibung: 2022-04-25
    Schlagwort(e): Ocean circulation ; Neodymium isotopes ; Carbon isotopes
    Repository-Name: Woods Hole Open Access Server
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