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  • Springer Nature  (2,023)
  • American Geophysical Union
  • Copernicus Publications (EGU)
  • 2020-2024  (2,439)
  • 2021  (2,273)
  • 2020  (166)
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  • 1
    Publication Date: 2024-06-27
    Description: Upwelling of nutrient-rich deep waters make eastern boundary upwelling systems (EBUSs), such as the Humboldt Current system, hot spots of marine productivity. Associated settling of organic matter to depth and consecutive aerobic decomposition results in large subsurface water volumes being oxygen depleted. Under these circumstances, organic matter remineralisation can continue via denitrification, which represents a major loss pathway for bioavailable nitrogen. Additionally, anaerobic ammonium oxidation can remove significant amounts of nitrogen in these areas. Here we assess the interplay of suboxic water upwelling and nitrogen cycling in a manipulative offshore mesocosm experiment. Measured denitrification rates in incubations with water from the oxygen-depleted bottom layer of the mesocosms (via 15N label incubations) mostly ranged between 5.5 and 20 nmol N2 L−1 h−1 (interquartile range), reaching up to 80 nmol N2 L−1 h−1. However, actual in situ rates in the mesocosms, estimated via Michaelis–Menten kinetic scaling, did most likely not exceed 0.2–4.2 nmol N2 L−1 h−1 (interquartile range) due to substrate limitation. In the surrounding Pacific, measured denitrification rates were similar, although indications of substrate limitation were detected only once. In contrast, anammox (anaerobic ammonium oxidation) made only a minor contribution to the overall nitrogen loss when encountered in both the mesocosms and the Pacific Ocean. This was potentially related to organic matter C / N stoichiometry and/or process-specific oxygen and hydrogen sulfide sensitivities. Over the first 38 d of the experiment, total nitrogen loss calculated from in situ rates of denitrification and anammox was comparable to estimates from a full nitrogen budget in the mesocosms and ranged between ∼ 1 and 5.5 µmol N L−1. This represents up to ∼  20 % of the initially bioavailable inorganic and organic nitrogen standing stocks. Interestingly, this loss is comparable to the total amount of particulate organic nitrogen that was exported into the sediment traps at the bottom of the mesocosms at about 20 m depth. Altogether, this suggests that a significant portion, if not the majority of nitrogen that could be exported to depth, is already lost, i.e. converted to N2 in a relatively shallow layer of the surface ocean, provided that there are oxygen-deficient conditions like those during coastal upwelling in our study. Published data for primary productivity and nitrogen loss in all EBUSs reinforce such conclusion.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2024-06-26
    Description: Observed oxygen minimum zones (OMZs) in the tropical Pacific Ocean are located above intermediate-depth waters (IDWs), defined here as the 500–1500 m water layer. Typical climate models do not represent IDW properties well and are characterized by OMZs that are too deep-reaching. We analyze the role of the IDW in the misrepresentation of oxygen levels in a heterogeneous subset of ocean models characterized by a horizontal resolution ranging from 0.1 to 2.8∘. First, we show that forcing the extratropical boundaries (30∘ S and N) to observed oxygen values results in a significant increase in oxygen levels in the intermediate eastern tropical region. Second, we highlight the fact that the Equatorial Intermediate Current System (EICS) is a key feature connecting the western and eastern part of the basin. Typical climate models lack in representing crucial aspects of this supply at intermediate depth, as the EICS is basically absent in models characterized by a resolution lower than 0.25∘. These two aspects add up to a “cascade of biases” that hampers the correct representation of oxygen levels at intermediate depth in the eastern tropical Pacific Ocean and potentially future OMZ projections.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2024-06-22
    Description: The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological timescales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage in vicinity of the modern Polar Front over a complete glacial-interglacial cycle (i.e., the past 140,000 years), based on sediment grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with weakened current strength during glacials and a stronger circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennialscale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We infer that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations modulated Pacific-Atlantic water exchange via the “cold water route” and potentially affected the Atlantic Meridional Overturning Circulation and marine carbon storage.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    American Geophysical Union
    In:  EPIC3Paleoceanography and Paleoclimatology, American Geophysical Union, 36(7), ISSN: 2572-4517
    Publication Date: 2024-06-22
    Description: Marine sedimentary records are a key archive when reconstructing past climate; however, mixing at the seabed (bioturbation) can strongly influence climate records, especially when sedimentation rates are low. By commingling the climate signal from different time periods, bioturbation both smooths climate records, by damping fast climate variations, and creates noise when measurements are made on samples containing small numbers of individual proxy carriers, such as foraminifera. Bioturbation also influences radiocarbon-based age-depth models, as sample ages may not represent the true ages of the sediment layers from which they were picked. While these effects were first described several decades ago, the advent of ultra-small-sample $^{14}$C dating now allows samples containing very small numbers of foraminifera to be measured, thus enabling us to directly measure the age-heterogeneity of sediment for the first time. Here, we use radiocarbon dates measured on replicated samples of 3-30 foraminifera to estimate age-heterogeneity for five marine sediment cores with sedimentation rates ranging from 2-30 cm kyr$^{-1}$. From their age-heterogeneities and sedimentation rates we infer mixing depths of 10-20 cm for our core sites. Our results show that when accounting for age-heterogeneity, the true error of radiocarbon dating can be several times larger than the reported measurement. We present estimates of this uncertainty as a function of sedimentation rate and the number of individuals per radiocarbon date. A better understanding of this uncertainty will help us to optimise radiocarbon measurements, construct age models with appropriate uncertainties and better interpret marine paleo records.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 5
    Publication Date: 2024-06-17
    Description: The aim of this paper is to investigate, through fnancial-statement analyzes, the economic fnancial performance of Italian hotels, after the international economic crisis, also con sidering the possible macro-regional diferences. The study focuses the fnancial state ments of 5473 hotels from 2009 to 2018. National data are also disaggregated in the three macro-areas that characterize Italy for diferent social and economic aspects. Anova test and Tukey–Kramer test are used. Results show that the crisis afected proftability. Ital ian hotels have a low capitalization, unable to cope with the large structural investments that require signifcant debts. The proftability indicators record similar trends in the three macro-areas, while the fnancial independence index and the coverage index show signif cant diferent values in the three observed areas. Therefore, in the digital era, Italian hotel industry has all the potential to restructure itself. Here fve ratios are considered to observe medium sized hotels. Future research with other variables will be useful, even on smaller hotels, and the analysis of their trends by cohorts of companies is necessary, as well as the integration of quantitative data with qualitative evidence. This paper encourages the cul ture of temporal sector comparison, re-evaluating the potential of accounting information systems, in order to promote data-based growth and development strategies. Furthermore, it contains indications for government ofcials, as well as for countries in the process of developing the hospitality sector following the example of the Italian experience.
    Description: Published
    Description: 383–407
    Description: OSA5: Energia e georisorse
    Description: N/A or not JCR
    Keywords: Italian hotels ; Tourism in Italy ; Economic-fnancial performance ; Crisis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2024-06-07
    Description: The University of Victoria Earth system climate model of intermediate complexity has been a useful tool in recent assessments of long-term climate changes including paleo-climate modelling. Since the last official release of the UVic ESCM 2.9, and the two official updates during the last decade, a lot of model development has taken place in multiple groups. The new version 2.10 of the University of Victoria Earth System Climate Model (UVic ESCM), to be used in the 6th phase of the coupled model intercomparison project (CMIP6), presented here combines and brings together multiple model developments and new components that have taken place since the last official release of the model. To set the foundation of its use, we here describe the UVic ESCM 2.10 and evaluate results from transient historical simulations against observational data. We find that the UVic ESCM 2.10 is capable of reproducing well changes in historical temperature and carbon fluxes, as well as the spatial distribution of many ocean tracers, including temperature, salinity, phosphate and nitrate. This is connected to a good representation of ocean physical properties. For the moment, there remain biases in ocean alkalinity and dissolved inorganic carbon, which will be addressed in the next updates to the model.
    Type: Article , PeerReviewed
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  • 7
    Publication Date: 2024-05-17
    Description: Combining proxy information and climate model simulations reconciles these sources of information about past climates. This, in turn, strengthens our understanding of past climatic changes. The analogue or proxy surrogate reconstruction method is a computationally cheap data assimilation approach, which searches in a pool of simulated climate states the best fit to proxy data. We use the approach to reconstruct European summer mean temperature from the 13th century until present using the Euro 2k set of proxy records and a pool of global climate simulation output fields. Our focus is on quantifying the uncertainty of the reconstruction, because previous applications of the analogue method rarely provided uncertainty ranges. We show several ways of estimating reconstruction uncertainty for the analogue method, which take into account the non-climate part of the variability in each proxy record. In general, our reconstruction agrees well at multi-decadal timescales with the Euro 2k reconstruction, which was conducted with two different statistical methods and no information from model simulations. In both methodological approaches, the decades around the year 1600 CE were the coldest. However, the approaches disagree on the warmest pre-industrial periods. The reconstructions from the analogue method also represent the local variations of the observed proxies. The diverse uncertainty estimates obtained from our analogue approaches can be locally larger or smaller than the estimates from the Euro 2k effort. Local uncertainties of the temperature reconstructions tend to be large in areas that are poorly covered by the proxy records. Uncertainties highlight the ambiguity of field-based reconstructions constrained by a limited set of proxies.
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2024-05-13
    Description: Dieses Open-Access-Buch erläutert ein Handlungsmodell zur Gestaltung sozialer Versorgung. Das Modell beinhaltet 16 Gestaltungsaufgaben, die sich an den wesentlichen Planungs- und Steuerungsaufgaben sozialer Versorgung und den vier Phasen eines Managementkreislaufes (Analyse, Strategieentwicklung, Umsetzung, Weiterentwicklung) orientieren. Dem Handlungsmodell liegt ein prozessorientiertes, reflexives und an der Sozialen Arbeit ausgerichtetes Handlungsverständnis zugrunde, das über „lineare“ Planungsansätze hinausreicht. Das Lehrbuch möchte Impulse für eine systematische und zugleich innovative Gestaltung sozialer Versorgung geben.
    Keywords: Social sciences ; Social work ; thema EDItEUR::J Society and Social Sciences::JK Social services and welfare, criminology::JKS Social welfare and social services::JKSN Social work
    Language: German
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  • 9
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    Springer Nature
    Publication Date: 2024-05-13
    Description: In diesem Open-Access-Buch wird die Bedeutung von religiösen Ritualen für die soziale Ordnung systematisch untersucht. Dazu werden Konzepte des Zusammenhangs von Ritualen mit verschiedenen Ebenen des Sozialen erarbeitet: Interaktion, Gemeinschaft und Gesellschaft.; In diesem Open-Access-Buch wird die Bedeutung von religiösen Ritualen für die soziale Ordnung systematisch untersucht. Dazu werden Konzepte des Zusammenhangs von Ritualen mit verschiedenen Ebenen des Sozialen erarbeitet: Interaktion, Gemeinschaft und Gesellschaft.
    Keywords: Social sciences ; Religion and sociology ; Social sciences—Philosophy ; thema EDItEUR::Q Philosophy and Religion::QR Religion and beliefs ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology::JHBA Social theory
    Language: German
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  • 10
    Publication Date: 2024-05-13
    Description: Communication Studies; Sustainable Development; Communications Engineering, Networks; Computer Systems Organization and Communication Networks
    Keywords: Communication Studies ; Sustainable Development ; Communications Engineering, Networks ; Computer Systems Organization and Communication Networks ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSV Zoology and animal sciences
    Language: English
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