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  • Springer  (155,123)
  • Nature Publishing Group
  • 2015-2019  (106,161)
  • 1980-1984  (48,423)
  • 1950-1954
  • 1945-1949  (7,456)
  • 2015  (106,161)
  • 1983  (48,423)
  • 1949  (7,456)
Collection
Years
  • 2015-2019  (106,161)
  • 1980-1984  (48,423)
  • 1950-1954
  • 1945-1949  (7,456)
Year
  • 1
    Publication Date: 2023-11-29
    Description: Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a key enzyme of the Calvin cycle, which is responsible for most of Earth's primary production. Although research on RubisCO genes and enzymes in plants, cyanobacteria and bacteria has been ongoing for years, still little is understood about its regulation and activation in bacteria. Even more so, hardly any information exists about the function of metagenomic RubisCOs and the role of the enzymes encoded on the flanking DNA owing to the lack of available function-based screens for seeking active RubisCOs from the environment. Here we present the first solely activity-based approach for identifying RubisCO active fosmid clones from a metagenomic library. We constructed a metagenomic library from hydrothermal vent fluids and screened 1056 fosmid clones. Twelve clones exhibited RubisCO activity and the metagenomic fragments resembled genes from Thiomicrospira crunogena. One of these clones was further analyzed. It contained a 35.2 kb metagenomic insert carrying the RubisCO gene cluster and flanking DNA regions. Knockouts of twelve genes and two intergenic regions on this metagenomic fragment demonstrated that the RubisCO activity was significantly impaired and was attributed to deletions in genes encoding putative transcriptional regulators and those believed to be vital for RubisCO activation. Our new technique revealed a novel link between a poorly characterized gene and RubisCO activity. This screen opens the door to directly investigating RubisCO genes and respective enzymes from environmental samples.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2023-11-08
    Description: The dynamics of the Loop Current (LC) in the Gulf of Mexico (GoM) during transient climates and interglacials, and its interaction with changes in sea level, atmospheric circulation, and Mississippi River (MR) discharge were studied. Geochemical proxy records and numerical modeling indicate that LC eddy shedding and its related heat transport into the GoM increased during the deglaciation. The model simulations imply decreased LC eddy shedding at lowered sea levels, while transports through Yucatan and Florida straits increased due to the southward migration of the Intertropical Convergence Zone (ITCZ) and increased wind-driven transport in the North Atlantic. Consistent with the model, (isotope) geochemical proxy records from the northern GoM show glacial/interglacial amplitudes significantly larger than in the Caribbean and extreme cooling during the Last Glacial Maximum (LGM) due to the vanishing LC eddy shedding. Prominent deglacial melt water releases observed south and west of the MR delta are neither present in the northeastern GoM, nor in sea-surface salinity-records in the subtropical North Atlantic. The freshwater signals were either a regionally restricted phenomenon or due to changes in the isotopic composition of the discharged water. Our results question the impact of MR megadischarges on the large-scale overturning circulation.
    Type: Book chapter , NonPeerReviewed
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  • 3
    Publication Date: 2023-11-08
    Description: The North Atlantic cold bias, associated with the misplacement of the North Atlantic Current (NAC) and typically extending from the surface to 1000 m depth, is a common problem in coupled models that compromises model fidelity. We investigate the use of a flow field correction (FFC) to adjust the path of the NAC and alleviate the cold bias. The FFC consists of three steps. First, climatological potential temperature (T) and salinity (S) fields for use with the model are produced using a three-dimensional restoring technique. Second, these T, S fields are used to modify the momentum equations of the ocean model. In the third stage, the correction term is diagnosed to construct a flow-independent correction. Results using the Kiel Climate Model show that the FFC allows the establishment of a northwest corner, substantially alleviating the subsurface cold bias. A cold bias remains at the surface but can be eliminated by additionally correcting the surface freshwater flux, without adjusting the surface heat flux seen by the ocean model. A model version in which only the surface fluxes of heat and freshwater are corrected continues to exhibit the incorrect path of the NAC and a strong subsurface bias. We also show that the bias in the atmospheric circulation is reduced in some corrected model versions. The FFC can be regarded as a way to correct for model error, e.g. associated with the deep water mass pathways and their impact on the large-scale ocean circulation, and unresolved processes such as eddy momentum flux convergence.
    Type: Article , PeerReviewed
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  • 4
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    Springer
    Publication Date: 2023-11-08
    Description: Definition: Seamounts are literally mountains rising from the seafloor. More specifically, they are “any geographically isolated topographic feature on the seafloor taller than 100 m, including ones whose summit regions may temporarily emerge above sea level, but not including features that are located on continental shelves or that are part of other major landmasses” (Staudigel et al., 2010). The term “guyot” can be used for seamounts having a truncated cone shape with a flat summit produced by erosion at sea level (Hess, 1946), development of carbonate reefs (e.g., Flood, 1999), or partial collapse due to caldera formation (e.g., Batiza et al., 1984). Seamounts 〈1,000 m tall are sometimes referred to as “knolls” (e.g., Hirano et al., 2008). “Petit spots” are a newly discovered subset of sea knolls confined to the bulge of subducting oceanic plates of oceanic plates seaward of deep-sea trenches (Hirano et al., 2006).
    Type: Book chapter , NonPeerReviewed
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  • 5
    Publication Date: 2023-09-19
    Description: Nitrous oxide is a potent greenhouse gas and a key compound in stratospheric ozone depletion. In the ocean, nitrous oxide is produced at intermediate depths through nitrification and denitrification, in particular at low oxygen concentrations. Although a third of natural emissions of nitrous oxide to the atmosphere originate from the ocean, considerable uncertainties in the distribution and magnitude of the emissions still exist. Here we present high-resolution surface measurements and vertical profiles of nitrous oxide that include the highest reported nitrous oxide concentrations in marine surface waters, suggesting that there is a hotspot of nitrous oxide emissions in high-productivity upwelling ecosystems along the Peruvian coast. We estimate that off Peru, the extremely high nitrous oxide supersaturations we observed drive a massive efflux of 0.2–0.9 Tg of nitrogen emitted as nitrous oxide per year, equivalent to 5–22% of previous estimates of global marine nitrous oxide emissions. Nutrient and gene abundance data suggest that coupled nitrification–denitrification in the upper oxygen minimum zone and transport of resulting nitrous oxide to the surface by upwelling lead to the high nitrous oxide concentrations. Our estimate of nitrous oxide emissions from the Peruvian coast surpasses values from similar, highly productive areas.
    Type: Article , PeerReviewed
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  • 6
    Publication Date: 2023-08-15
    Description: This book is an update of the first BACC assessment, published in 2008. It offers new and updated scientific findings in regional climate research for the Baltic Sea basin. These include climate changes since the last glaciation (approx. 12,000 years ago), changes in the recent past (the last 200 years), climate projections up until 2100 using state-of-the-art regional climate models and an assessment of climate-change impacts on terrestrial, freshwater and marine ecosystems. There are dedicated new chapters on sea-level rise, coastal erosion and impacts on urban areas. A new set of chapters deals with possible causes of regional climate change along with the global effects of increased greenhouse gas concentrations, namely atmospheric aerosols and land-cover change. The evidence collected and presented in this book shows that the regional climate has already started to change and this is expected to continue. Projections of potential future climates show that the region will probably become considerably warmer and wetter in some parts, but dryer in others. Terrestrial and aquatic ecosystems have already shown adjustments to increased temperatures and are expected to undergo further changes in the near future. The BACC II Author Team consists of 141 scientists from 12 countries, covering various disciplines related to climate research and related impacts. BACC II is a project of the Baltic Earth research network and contributes to the World Climate Research Programme.
    Type: Book , NonPeerReviewed
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  • 7
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    Springer
    In:  EPIC3Berlin, Springer, 447 p., ISBN: 978-3-319-16510-3
    Publication Date: 2023-06-21
    Description: This book describes how manmade litter, primarily plastic, has spread into the remotest parts of the oceans and covers all aspects of this pollution problem from the impacts on wildlife and human health to socio-economic and political issues. Marine litter is a prime threat to marine wildlife, habitats and food webs worldwide. The book illustrates how advanced technologies from deep-sea research, microbiology and mathematic modelling as well as classic beach litter counts by volunteers contributed to the broad awareness of marine litter as a problem of global significance. The authors summarise more than five decades of marine litter research, which receives growing attention after the recent discovery of great oceanic garbage patches and the ubiquity of microscopic plastic particles in marine organisms and habitats. In 16 chapters, authors from all over the world have created a universal view on the diverse field of marine litter pollution, the biological impacts, dedicated research activities, and the various national and international legislative efforts to combat this environmental problem. They recommend future research directions necessary for a comprehensive understanding of this environmental issue and the development of efficient management strategies. This book addresses scientists, and it provides a solid knowledge base for policy makers, NGOs, and the broader public.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Book , peerRev
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  • 8
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    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, (Springer Earth System Sciences), Heidelberg [u.a.], Springer, Toward, 251 p., pp. 139-148, ISBN: 978-3-319-13865-7
    Publication Date: 2023-06-21
    Description: Sea-ice elevation profiles and thickness measurements have been collected during summer 2011 in the Central Arctic. These two different data sets have been combined in order to obtain surface and bottom topography of the sea-ice. From the bottom profile, the keels of ridges are detected. Then, a parameterization of oceanic drag coefficients that accounts for the keels depth and density is applied. The calculated oceanic drag coefficients are highly variable (between about 2 × 10−3 and about 8 × 10−3) within the range of observed values. In order to estimate the contribution of variable drag coefficients on the Ekman pumping, the calculated drag coefficients are used in an idealized model experiment, where sea ice is drifting at constant velocity on an ocean at rest. The resulting variations of the Ekman vertical velocity are in the same order of magnitude as for variable ice velocity at the surface. In most state-of-the-art general circulation models, the variations of drag coefficients are not taken into account. The simple experiment carried out in the present study suggests that neglecting this contribution can lead to an incorrect representation of the momentum exchange between ice and ocean and to an underestimation of the Ekman pumping, with consequences for the large scale ocean circulation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 9
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    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Earth System Science—Past Experiences and Future Trends, Heidelberg, Springer, pp. 3-7, ISBN: 978-3-319-13864-0, ISSN: 2197-9596
    Publication Date: 2023-06-21
    Description: Earth System Science has developed over the last two decades from an interesting concept in Earth sciences education to a fully integrative science focussed on understanding the complex system Earth. This evolution is partially due to the radical and far reaching anthropogenic changes and the general feeling of helplessness with regards to the possible consequences and future impacts on the Earth System. This paper proposes that a paradigm shift in undergraduate and graduate education is needed to further develop Earth System Science. Graduate programs such as the Earth System Science Research School (ESSReS), which are intrinsically trans- and interdisciplinary will help to change rigid subject specific mind-set among faculty and students. The health and sustainability of our planet is at stake
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 10
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    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Towards an Interdisciplinary Approach in Earth System Science, Heidelberg, Springer, pp. 161-170, ISBN: 978-3-319-13864-0, ISSN: 2197-9596
    Publication Date: 2023-06-21
    Description: Components of the climate system, such as ice sheets and marine sediments serve as invaluable archives, which can be tapped into, to reconstruct paleoclimate conditions. The relative abundance of hydrogen and oxygen isotopes in ice cores is a proxy for past local temperature evolution. However the translation of these proxies into temperature is not straightforward. Complex interdependencies in the climate system can hide or override the local climate signal at which the ice core was drilled. Using 3D ice sheet modelling in concert with passive tracer advection one can simulate the isotopic distribution in ice sheets and compare them to ice core data. Combining this method in a coupled climate model environment, containing atmosphere and ocean components, one can theoretically simulate the isotopic cycle from the source to the actual ice record. Such an approach would greatly support the interpretation of proxy data whilst constraining the output of 3D ice sheet models (ISMs). We present the implementation of passive tracer advection in our 3D ISM RIMBAY (Thoma et al. in Geosci Model Dev 1:1–21, 2014, Goeller et al. in Cryosphere 7:1095–1106, 2014) and asses the potential of the method to reproduce chronologies of the polar ice sheets
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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