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  • 2020-2024  (40,625)
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  • 1
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    Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
    In:  EPIC3Berichte zur Polar- und Meeresforschung = Reports on polar and marine research, Bremerhaven, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 786, 65 p., pp. 1-65, ISSN: 1866-3192
    Publication Date: 2024-06-14
    Repository Name: EPIC Alfred Wegener Institut
    Type: "Berichte zur Polar- und Meeresforschung" , notRev
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  • 2
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    Naturalis Biodiversity Center
    In:  Blumea: Biodiversity, Evolution and Biogeography of Plants vol. 66 no. 1, pp. 82-92
    Publication Date: 2024-06-14
    Description: The original set of botanical collections of the agronomist H.A. Homblé is conserved in the herbarium BR. Homblé was one of the first collectors (1911–1913) for the flora of Katanga, Democratic Republic of the Congo. Many Homblé specimens were described as taxonomic novelties; 107 tropical African plant species are named after him. Before his colonial career in Katanga, Homblé stayed about two years (1909–1911) in Guangxi, China. His incompletely labelled Chinese collections were erroneously considered as collected in Katanga. This supposed African origin has led to confusion with regard to the identification, and even resulted in the description of four species believed to be new for science. This paper presents and discusses Homblé’s collection made in Guangxi, and the assumed novelties in it. Drosera insolita is a synonym of the Asian Drosera lunata, widespread from India to Australia. Three other species are new synonyms. Caesalpinia homblei is a synonym of the pantropical Caesalpinia bonduc. Digitaria polybotryoides is a synonym of Digitaria abludens, a widespread species in tropical Asia. Grewia katangensis is the only species that proved to be synonymous with an endemic species, Grewia cuspidatoserrata, only known from S Yunnan, and here reported as a new record for Guangxi. Lysimachia candida and Impatiens chinensis should be deleted from the list of the Congo Flora. The importance of careful specimen labelling and label interpretation is discussed.
    Keywords: Plant Science ; Ecology ; Evolution ; Behavior and Systematics
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
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  • 3
    Publication Date: 2024-06-13
    Description: Southern hemisphere humpback whale (Megaptera novaeangliae, SHHW) breeding populations follow a high-fidelity Antarctic krill (Euphausia superba) diet while feeding in distinct sectors of the Southern Ocean. Their capital breeding life history requires predictable ecosystem productivity to fuel migration and migration-related behaviours. It is therefore postulated that populations feeding in areas subject to the strongest climate change impacts are more likely to show the first signs of a departure from a high-fidelity krill diet. We tested this hypothesis by investigating blubber fatty acid profiles and skin stable isotopes obtained from five SHHW populations in 2019, and comparing them to Antarctic krill stable isotopes sampled in three SHHW feeding areas in the Southern Ocean in 2019. Fatty acid profiles and δ13C and δ15N varied significantly among all five populations, however, calculated trophic positions did not (2.7 to 3.1). Similarly, fatty acid ratios, 16:1ω7c/16:0 and 20:5ω3/22:6ω3 were above 1, showing that whales from all five populations are secondary heterotrophs following an omnivorous diet with a diatom-origin. Thus, evidence for a potential departure from a high-fidelity Antarctic krill diet was not seen in any population. δ13C of all populations were similar to δ13C of krill sampled in productive upwelling areas or the marginal sea-ice zone. Consistency in trophic position and diet origin but significant fatty acid and stable isotope differences demonstrate that the observed variability arises at lower trophic levels. Our results indicate that, at present, there is no evidence of a divergence from a high-fidelity krill diet. Nevertheless, the characteristic isotopic signal of whales feeding in productive upwelling areas, or in the marginal sea-ice zone, implies that future cryosphere reductions could impact their feeding ecology.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Public Library of Science (PLoS)
    In:  EPIC3PLOS Climate, Public Library of Science (PLoS), 3(3), pp. e0000358-e0000358, ISSN: 2767-3200
    Publication Date: 2024-06-13
    Description: 〈jats:p〉Food-webs are a critical feature of ecosystems and help us understand how communities will respond to climate change. The Southern Ocean is facing rapid and accelerating changes due to climate change. Though having evolved in an isolated and somewhat extreme environment, Southern Ocean biodiversity and food-webs are among the most vulnerable. Here, we review 1) current knowledge on Southern Ocean food-webs; 2) methods to study food-webs; 3) assessment of current and future impacts of climate change on Southern Ocean food-webs; 4) knowledge gaps; and 5) the role of Early Career Researchers (ECRs) in future studies. Most knowledge on Southern Ocean food-webs come from the pelagic environment, both at macro- and microbial levels. Modelling and diet studies of individual species are major contributors to the food-web knowledge. These studies revealed a short food-web, predominantly sustained by Antarctic Krill (〈jats:italic〉Euphausia superba〈/jats:italic〉). Additionally, alternative pathways exist, involving other krill species, fish, and squid, which play equally important roles in connecting primary producers with top predators. Advantages and disadvantages of several techniques used to study Southern Ocean food-webs were identified, from the classical analyses of stomach contents, scats, or boluses to the most recent approaches such as metabarcoding and trophic-biomarkers. Observations show that climate change can impact the food-web in different ways. As an example, changes to smaller phytoplankton species can lengthen the food-web, increasing assimilation losses and/or changing nutrient cycles. Future studies need to focus on the benthic-dominated food-webs and the benthopelagic coupling. Furthermore, research during the winter season and below the ice-shelves is needed as these areas may play a crucial role in the functioning of this ecosystem. ECRs can play a significant role in advancing the study of Southern Ocean food-webs due to their willingness for interdisciplinary collaboration and proficiency in employing various methodologies, contributing to the construction of high-resolution food-webs.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Taylor & Francis
    In:  EPIC3Arctic Antarctic and Alpine Research, Taylor & Francis, 56(1), pp. 2350546-2350546, ISSN: 1523-0430
    Publication Date: 2024-06-13
    Description: Arctic landscapes are characterized by diverse water bodies, which are covered with ice for most of the year. Ice controls surface albedo, hydrological properties, gas exchange, and ecosystem services, but freezing processes differ between water bodies. We studied the influence of geomor-phology and meteorology on winter ice of water bodies in the Lena Delta, Siberia. Electrical conductivity (EC) and stable water isotopes of ice cores from four winters and six water bodies were measured at unprecedented resolution down to 2-cm increments, revealing differences in freezing systems. Open-system freezing shows near-constant isotopic and EC gradients in ice, whereas closed-system freezing shows decreasing isotopic composition with depth. Lena River ice displays three zones of isotopic composition within the ice, reflecting open-system freezing that records changing water sources over the winter. The isotope composition of ice covers in landscape units of different ages also reflects the individual water reservoir settings (i.e., Pleistocene vs. Holocene ground ice thaw). Ice growth models indicate that snow properties are a dominant determinant of ice growth over winter. Our findings provide novel insights into the winter hydro-chemistry of Arctic ice covers, including the influences of meteorology and water body geomor-phology on freezing rates and processes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
    Publication Date: 2024-06-13
    Description: Volcanic rocks are the prominent host rocks in geothermal and volcanic systems in general, displaying heterogeneity. Although various external factors such as temperature, pressure, time, fluid chemistry, and subsurface geology have been thoroughly researched regarding the source of hydrothermal minerals in geothermal fields, the effect of hydrothermal alteration on volcanic hosts is still controversial in the literature. This review compiles data on the physical and mechanical properties of the host rocks composing volcanic environments exhibiting hydrothermal alteration or remaining unaltered. The considered data is originated from hydrothermal areas from Kuril-Kamchatka (Russia), Los Humeros (Mexico), Ngatamaraki, Rotokawa, Kawerau and Ohakuri geothermal fields and Mt. Ruapehu, Mt. Taranaki, and Whakaari volcanoes (New Zealand), Solfatara (Italy), Reykjanes, Nesjavellir, and Theistarereykir geothermal fields (Iceland), La Soufrière de Guadeloupe (Caribbean) volcano, and Merapi volcano (Indonesia). Analysis of average values displayed in several graphical representations and correlations finds that dense rocks (such as lavas and intrusive rocks) exhibit greater competence and lower porosity than fragmental rocks. However, altered dense rocks display greater variability in mechanical properties compared to pyroclastic rocks, primarily influenced by mineral dissolution leading to rock weakening. Exceptions occur for high-temperature hydrothermal alteration, such as advanced silicification and propylitic alteration, with the latter influenced by minor types of alteration. Fragmental rocks have diverse behaviour with the extent of hydrothermal alteration and welding/compaction. According to the compiled data, an overall strengthening of pyroclastic rocks develops as hydrothermal alteration increases, regardless of the type of hydrothermal alteration. The complexity of hydrothermal systems, the variability shown by different hydrothermal settings and histories in terms of temperature, fluid chemistry and secondary mineral assemblage, and the variety of rock materials with different microstructures contribute to moderate correlations between properties compared to those established in an unaltered state. However, the same trends (linear, nonlinear, positive, negative) are preserved along hydrothermal alteration. This review emphasizes the significance of the type and degree of hydrothermal alteration, along with the rock type and pre-existence of fractures, in shaping the development of alteration in volcanic environments and modifying the properties of host rocks. The relevance of the review relies on the fact that these properties are considered to enhance the productivity of geothermal fields and improve the assessment of volcanic hazards. Future research is expected to expand on this groundwork.
    Description: Published
    Description: 104754
    Description: OSV4: Preparazione alle crisi vulcaniche
    Description: JCR Journal
    Keywords: Hydrothermal alteration ; physical properties ; degree of hydrothermal alteration ; mechanical properties ; hydrothermal alteration facies ; intrusion-related geothermal systems ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2024-06-13
    Description: Ground-based high resolution observations of downward longwave irradiance (DLI), surface air temperature, water vapour surface partial pressure and column amount, zenith sky infrared (IR) radiance in the atmospheric window, and all-sky camera images are regularly obtained at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5° N, 68.8° W), North-West Greenland. The datasets for the years 2017 and 2018 have been used to assess the performance of different empirical formulas to infer clear sky DLI. An algorithm to identify clear sky observations has been developed, based on value, variability, and persistence of zenith sky IR radiance. Seventeen different formulas to estimate DLI have been tested against the THAAO dataset, using the originally determined coefficients. The formulas which combine information on total column water vapour and surface air temperature appear to perform better than others, with a mean bias with respect to the measured DLI smaller than 1 W/m2 and a root mean squared error (RMSE) around 6 W/m2. Some formulas, specifically developed for the Arctic, are found to produce poor statistical results; this is attributed partly to limitations in the originally used dataset, which does not cover a whole year, or is relative to very specific conditions (i.e., the ice sheet). The bias displays a significant improvement when the coefficients of the different formulas are calculated using the THAAO dataset. The presence of two full years of data allows the investigation of the inter-annual variability, and the use of different years for the determination of the coefficients and the evaluation of results. The smallest values of the bias and RMSE reach 0.1 W/m2 and 5 W/m2, respectively. Overall, best results are found for formulas which use both surface parameters and total water vapour column, and have been developed from global datasets. Conversely, formulas which express the atmospheric emissivity as a linear function of the logarithm of the column integrated water vapour appear to poorly reproduce the observations at THAAO.
    Description: Published
    Description: 1617–1632
    Description: OSA2: Evoluzione climatica: effetti e loro mitigazione
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2024-06-13
    Description: We aim to compute macroseismic parameters (location and magnitude) using the BOXER code for the first time on the citizen testimonies, that is, individual intensity data points (IDPs) at the global scale collected and made available by the LastQuake system of the European–Mediterranean Seismological Centre (EMSC). IDPs available for different earthquakes are selected to eliminate those that are geographically inconsistent with most data; then they are clustered spatially based on various methods. For each cluster with at least three IDPs, a macroseismic data point (MDP), corresponding to an intensity value assessed for given localities as in classical macroseismic studies, is computed by various central tendency estimators (average, median, and trimmed averages). Finally, macroseismic parameters are obtained by MDP distribution using two location methods of BOXER code. For each earthquake, we used raw and corrected intensities and 132 different combinations of grouping methods, estimators, and BOXER methods. We assigned a ranking to the combinations that best reproduce instrumental parameters and used such a ranking to select preferred combinations for each earthquake. We analyzed retrospectively the reliability of the parameters as a function of time and space. The results are essentially identical using original and corrected intensities and show higher reliability for BOXER’s method 1 than for method 0; they are dependent on the geographical area, and generally improve over time and with the number of IDPs collected. These findings are useful for the future real-time analyses, and for evaluating the location and magnitude of earthquakes whenever a sufficient number of IDPs are available and with a distribution such that MDPs can be derived and the BOXER method applied.
    Description: Published
    Description: 969–996
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2024-06-13
    Description: The ability to predict the mobility of rock avalanches is necessary when designing strategies to mitigate the risks they pose. A popular mobility indicator of the flow front is the Heim’s apparent friction coefficient muH. In the field, muH shows a decrease in value as flow volume V increases. But this correlation has been a mystery as to whether it is due to a causal relationship between V and mobility since: (1) field data of muH do not collapse onto a single curve because typically widely scattered and (2) laboratory experiments have shown an opposite volume effect on the center of mass mobility of miniature flows. My numerical simulations confirm for the first time the existence of a functional relationship of scaling parameters where muH decreases as V increases in unsteady and nonuniform 3D flows. Data scatter is caused by muH that is affected by numerous other variables besides V. The interplay of these variables produces different granular regimes with opposite volume effects. In particular, muH decreases as V increases in the regime characterized by a relatively rough subsurface. The relationship holds for large-scale flows that, like rock avalanches, consist of a very large number of fine clasts traveling in wide channels. In these dense flows, flow front mobility increases as flow volume increases, as channel width increases, as grain size decreases, as basal friction decreases and as flow scale increases. Larger-scale flows are more mobile because they have larger Froude number values.
    Description: Published
    Description: 933–947
    Description: OSV1: Verso la previsione dei fenomeni vulcanici pericolosi
    Description: JCR Journal
    Keywords: Pyroclastic Flows ; Rock Avalanches ; Flow Front ; Mobility
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2024-06-13
    Description: Underdetermination is a condition affecting all problems in seismic imaging. It manifests mainly in the nonuniqueness of the models inferred from the data. This condition is exacerbated if simplifying hypotheses like isotropy are discarded in favor of more realistic anisotropic models that, although supported by seismological evidence, require more free parameters. Investigating the connections between underdetermination and anisotropy requires the implementation of solvers which explore the whole family of possibilities behind nonuniqueness and allow for more informed conclusions about the interpretation of the seismic models. Because these aspects cannot be investigated using traditional iterative linearized inversion schemes with regularization constraints that collapse the infinite possible models into a unique solution, we explore the application of transdimensional Bayesian Monte Carlo sampling to address the consequences of underdetermination in anisotropic seismic imaging. We show how teleseismic waves of P and S phases can constrain upper‐mantle anisotropy and the amount of additional information these data provide in terms of uncertainty and trade‐offs among multiple fields.
    Description: Published
    Description: 1214–1226
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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