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  • 1
  • 2
    Call number: MOP 19538/1d-6d
    Type of Medium: Monograph available for loan
    Pages: 111 S.
    ISSN: 0486-2287
    Language: Russian
    Note: In kyrill. Schr.
    Location: MOP - must be ordered
    Branch Library: GFZ Library
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  • 3
    Call number: Z 06.0500
    Type of Medium: Journal available for loan
    Pages: 30 cm
    ISSN: 1824-7741
    Former Title: Vorgänger Geologisch-paläontologische Mitteilungen, Innsbruck
    Language: German , English
    Note: Ersch. unregelmäßig , Beiträge teilweise in Englisch
    Branch Library: GFZ Library
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  • 4
    Monograph available for loan
    Monograph available for loan
    Garmisch-Partenkirchen : Institut für atmosphärische Umweltforschung der Fraunhofer- Gesellschaft
    Call number: MOP 44829 / Mitte
    Type of Medium: Monograph available for loan
    Pages: 25 S. , graph. Darst.
    Language: English
    Location: MOP - must be ordered
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  • 5
    Call number: S 90.0066(162,1)
    In: Geologisches Jahrbuch / A
    Type of Medium: Series available for loan
    Pages: 261 Seiten , Ill., 1 DVD-ROM (12 cm) und 1 Tafel-Beil. ([2] S.)
    ISBN: 9783510968534
    Series Statement: Geologisches Jahrbuch 162
    Classification:
    Engineering Geophysics
    Language: German
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 6
    Call number: AWI A3-20-93434-2
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 2
    Type of Medium: Series available for loan
    Pages: 218 Seiten , Illustrationen
    Series Statement: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,2
    Language: German
    Note: Zugleich: Dissertation, Freie Unversität Berlin, [ca. 1963] , INHALTSVERZEICHNIS PROBLEMSTELLUNG UND ZIELSETZUNG 1. BEMERKUNGEN ZUM BEOBACHTUNGSGELÄNDE UND ZUM BEOBACHTUNGSMATERIAL 1.1 Das Beobachtungsgelände 1.2 Das Beobachtungsmaterial 2. HOMOGENITÄTSBETRACHTUNGEN 2.1 Temperatur 2.2 Niederschlag 2.3 Wind 2.4 Sonnenschein und Bewölkung 3. TEMPERATURVERHÄLTNISSE 3.1 Monats- und Jahreswerte 3.2 Tageswerte 3.3 Pentadenwerte 3.4 Häufigkeitsbetrachtungen 3.5 Interdiurne Veränderlichkeit 3.6 Der tägliche Gang 3.7 Vorkommen bestimmter Schwellenwerte 3.71 Frost- und Eistage 3.72 Sommer- und Tropentage 4. DER WASSERGEHALT DER LUFT 4.1 Monats- und Jahreswerte 4.2 Tageswerte 4.3 Häufigkeitsbetrachtungen 4.4 Interdiurne Veränderlichkeit 4.5 Der tägliche Gang 5. BEWÖLKUNGSVERHÄLTNISSE 5.1 Monats- und Jahreswerte 5.2 Tageswerte 5.3 Häufigkeitsbetrachtungen 5.4 Der tägliche Gang 5.5 Heitere und trübe Tage 5.6 Nebel 6. SONNENSCHEIN 6.1 Monats- und Jahreswerte 6.2 Tageswerte 6.3 Der tägliche Gang 7. NIEDERSCHLAGSVERHÄLTNISSE 7.1 Monats- und Jahreswerte 7.2 Niederschlagsbereitschaft 7.3 Tageswerte 7.4 Der tägliche Gang 7.5 Häufigkeitsbetrachtungen 7.6 Niederschlags- und Trockenperioden 7.7 Niederschlag und Wind· 7.8 Schneeverhältnisse 7.81 Schneefall und Schneedecke 7.82 Schneehöhe 7.9 Gewitter 8. WINDVERHÄLTNISSE 8.1 Windrichtung 8.2 Windgeschwindigkeit 8.21 Der jährliche Gang 8.22 Häufigkeitsbetrachtungen 8.23 Sturmtage und Windstillen 8.24 Der tägliche Gang 9.ZUSAMMENFASSUNG VERZEICHNIS DER TEXTTABELLEN VERZEICHNIS DER ABBILDUNGEN LITERATURVERZEICHNIS TABELLENANHANG
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  • 7
    Call number: IASS 15.89494
    Type of Medium: Monograph available for loan
    Pages: Losebl.-Ausg.
    Edition: Stand: Oktober 2010
    ISBN: 9783768501828
    Language: German
    Branch Library: IASS Library
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  • 8
    Monograph available for loan
    Monograph available for loan
    [Edgecumbe, N.Z.] : A. Muller
    Call number: M 15.89146
    Description / Table of Contents: An account of the results of the 2 March 1987 earthquake in the eastern Bay of Plenty and the aftermath's effects on the people and places on the Rangitaiki Plains
    Type of Medium: Monograph available for loan
    Pages: 223 S., , Ill.
    Language: English
    Branch Library: GFZ Library
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  • 9
    Call number: PIK N 453-17-91096
    Type of Medium: Monograph available for loan
    Pages: 50 Seiten , Illustrationen, Diagramme
    Language: German
    Location: A 18 - must be ordered
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  • 10
    Monograph non-lending collection
    Monograph non-lending collection
    Leiden : Nijhoff ; 1.2009 -
    Call number: IASS 17.92082
    Type of Medium: Monograph non-lending collection
    ISSN: 1876-8814
    Language: English
    Branch Library: IASS Library
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  • 11
    Call number: (DE-599)GBV03709842X
    Type of Medium: Monograph available for loan
    Language: German
    Location: MOP - must be ordered
    Branch Library: GFZ Library
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  • 12
    Call number: 3/S 07.0034(2016)
    In: Annual report
    Type of Medium: Monograph available for loan
    Pages: 51 Seiten
    ISSN: 1865-6439 , 1865-6447
    Parallel Title: Erscheint auch als Annual report ... / Helmholtz Association of German Research Centres
    Language: English
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  • 13
    Monograph available for loan
    Monograph available for loan
    Leningrad : Gidrometeorolog. Izd.
    Call number: MOP 33767
    Type of Medium: Monograph available for loan
    Pages: 663 S.
    Language: Russian
    Note: In kyrill. Schr., russ.
    Location: MOP - must be ordered
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  • 14
    Call number: AWI G6-19-92375
    In: Berichte / Christian-Albrechts-Universität zu Kiel, Institut für Geowissenschaften, Nr. 9
    Type of Medium: Monograph available for loan
    Pages: 278 Seiten , Illustrationen
    ISSN: 0175-9302
    Series Statement: Berichte / Christian-Albrechts-Universität zu Kiel, Institut für Geowissenschaften 9
    Language: German
    Note: Zugleich: Dissertation, Christian-Albrechts-Universität zu Kiel, 1999 , INHALTSVERZEICHNIS 1. Einleitung 1.1 Kenntnisstand und offene Fragen 1.2 Fragestellung und Ziele dieser Arbeit 2. Umweltbedingungen in den Arbeitsgebieten 2.1 Hydrographie, Eisverhältnisse und NAO 2.2 Zur Variation von Wassertiefe und Breite der Dänemarkstraße und zur Vereisung Islands während des letzten Glazials 3. Methoden 3.1 Auswahl der Kernstationen 3.2 Probennahme und Analysen (Übersicht) 3.3 Zur Rekonstruktion von Paläobedingungen im Oberflächenwasser Zur Aussage stabiler Isotopenverhältnisse in planktischen Foraminiferen Zur Messung stabiler Isotopenverhältnisse Zur Massenspektrometrie Zur Rekonstruktion von Oberflächentemperaturen Alkane und Alkohole als Maß für Staubeintrag Eistranspmtiertes Material und vulkanische Aschen 3.4 Zur Rekonstruktion von Paläobedingungen im Zwischen-/ Tiefenwasser Häufigkeit von Cibicides- und anderen benthischen Arten (inkl. Taxonomie) Stabile Isotopenverhältnisse in benthischen Foraminiferen 3.5 AMS 14C-Datierungen Probenreinigung 3. 6 Hauptelementanalysen von vulkanischen Asche-Leithorizonten 3. 7 Geomagnetische Meßgrößen und magnetische Suszeptibiltät 3.8 Techniken zur Spektralanalyse 4. Methodische Ergebnisse 4.1 Zum Einfluß der Probenreinigung auf δ18O-/ δ13C-Werte 4.2 Probleme bei der langfristigen Reproduzierbarkeit von δ18O-Zeitreihen 4.3 Einfluß der Korngröße und Artendefinition planktischer Foraminiferen auf SST-Rekonstruktionen in hohen Breiten 4.4 Vergleich der stabilen Isotopenwerte von Cibicides lobatulus und Cibicidoides wuellerstorfi 5. Stratigraphische Grundlagen und Tiefenprofile der Klimasignale 5.1 Stratigraphische Korrelation zwischen parallel-gekernten GKG- und SL-/KL-Profilen 5.2 Flanktische δ18O-/ δ13C-Kurven, 14C-Alter und biostratigraphische Fixpunkte Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Kern 23351 Vøring-Plateau Kern 23071 Kern 23074 5.3 Benthische δ18O-/ δ13C-Werte in Kern PS2644 5.4 Siliziklastische Sedimentkomponenten: Eistransportiertes Material Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Vøring-Plateau Kern 23071 Kern 23074 5.5 Vulkanische Glasscherben in Kern PS2644: Wind- und Eiseintrag 5.6 Geochemie und Alter einzelner Tephralagen als Leithorizonte Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Vøring-Plateau Kern 23071 Kern 23074 5.7 Magnetische Suszeptibilität in den Kernen PS2644, PS2646 und PS2647 Kern PS2644 Kern PS2646 und PS2647 5.8 Geomagnetische Feldintensität und Richtungsänderungen in Kern PS2644 5.9 Variation von Planktonfauna und -flora Westliches Islandbecken: Kern PS2644 Kern PS2646 und PS2647 Vøring-Plateau: Kern 23071 und 23074 5.10 Benthische Foraminiferen in Kern PS2644 6. Entwicklung von Temperatur und Salzgehalt nördlich der Dänemark-Straße 6.1 Variation der Oberflächentemperatur nach Planktonforaminiferen 6.2 Variation der Oberflächentemperatur nach Uk37 6.3 Variation der Oberflächensalinität 7. Die Feinstratigraphie von Kern PS2644 als Basis für eine Eichung der 14C-Altersskala 22 - 55 ka 7.1 Korrelation zwischen den Klimasignalen in Kern PS2644 und der GISP2-Klimakurve zum Kalibrieren der 14C-Alter und Erstellen eines Altersmodells Tephrachronologische Marker Korrelationsparameter und -regeln Sonderfälle/ Probleme bei der Korrelation 7.2 Alters-stratigraphische Korrelation der Klimakurven von Kern 23071 und 23074 7.3 Variation der Altersanomalien zwischen 20 und 55 14C-ka 7.4 Variabilität des planktischen 14C-Reservoiralters in Schmelzwasserbeeinflußten Seegebieten Variation der planktischen 14C-Alter unmittelbar an der Basis von Heinrich-Ereignis 4 Unterschiede zwischen planktischen und benthischen 14C-Altern in der westlichen Islandsee. Zur Erklärung der inversen Altersdifferenzen 7.5 Differenz zwischen 14C- und Kalenderalter: Zeitliche Variation unter Einfluß des Erdmagnetfeldes - Modell und Befund 7.6 Sedimentationsraten der Kerne 23071, 23074 und PS2644 nach dem GISP2-Altersmodell Vøring-Plateau: Kerne 23071 und 23074 Südwest-Islandsee: Kern PS2644 8. Klimaoszillationen im Europäischen Nordmeer in der Zeit und Frequenzdomäne 8.1 "Der Einzelzyklus" in den Klimakurven von Kern PS2644 8.2 Zur Veränderlichkeit der Warm- und Kaltextreme sowie Zyklenlänge Besonderheiten in der Zyklenlänge Variation der Kalt-(Stadiale) Variation der Interstadiale 8.3 Periodizitäten der Klimasignale im Frequenzband der D.-Oe.-Zyklen. Der D.-Oe.-Zyklus von 1470 J., seine Multiplen und harmonischen Schwingungen Weitere Frequenzen: 1000-1150 Jahre- und 490- 510 Jahre-Zyklizitäten Höhere Frequenzen im Bereich von Jahrhunderten und Dekaden 8.4 Phasenbeziehungen und (örtliche) Steuemngsmechanismen der Dansgaard-Oeschger-Zyklen 9. Schlußfolgerungen Danksagung Literaturverzeichnis Anhang
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  • 15
    Monograph available for loan
    Monograph available for loan
    Madrid : Secc
    Call number: PIK N 456-17-90913
    Type of Medium: Monograph available for loan
    Pages: 536 Seiten
    Series Statement: Ministerio de Transportes Turismo Y Comunicaciones : Publicación Serie A 114
    Parallel Title: 1,1=6; 2,1=13 von Publicaciones / D / Ministerio del Aire, Subsecretaria de Aviación Civil, Servicio Meteorológico Nacional
    Language: Spanish
    Location: A 18 - must be ordered
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  • 16
    Monograph available for loan
    Monograph available for loan
    London : Penguin Books
    Type of Medium: Monograph available for loan
    ISBN: 9780141985206
    Language: English
    Branch Library: IASS Library
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  • 17
    Call number: AWI A3-20-93434
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 1
    Type of Medium: Series available for loan
    Pages: 121 Seiten , Illustrationen
    Series Statement: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,1
    Language: German
    Note: Zugleich: Dissertation, Freie Unversität Berlin, [ca. 1963] , INHALTSVERZEICHNIS PROBLEMSTELLUNG UND ZIELSETZUNG 1. BEMERKUNGEN ZUM BEOBACHTUNGSGELÄNDE UND ZUM BEOBACHTUNGSMATERIAL 1.1 Das Beobachtungsgelände 1.2 Das Beobachtungsmaterial 2. HOMOGENITÄTSBETRACHTUNGEN 2.1 Temperatur 2.2 Niederschlag 2.3 Wind 2.4 Sonnenschein und Bewölkung 3. TEMPERATURVERHÄLTNISSE 3.1 Monats- und Jahreswerte 3.2 Tageswerte 3.3 Pentadenwerte 3.4 Häufigkeitsbetrachtungen 3.5 Interdiurne Veränderlichkeit 3.6 Der tägliche Gang 3.7 Vorkommen bestimmter Schwellenwerte 3.71 Frost- und Eistage 3.72 Sommer- und Tropentage 4. DER WASSERGEHALT DER LUFT 4.1 Monats- und Jahreswerte 4.2 Tageswerte 4.3 Häufigkeitsbetrachtungen 4.4 Interdiurne Veränderlichkeit 4.5 Der tägliche Gang 5. BEWÖLKUNGSVERHÄLTNISSE 5.1 Monats- und Jahreswerte 5.2 Tageswerte 5.3 Häufigkeitsbetrachtungen 5.4 Der tägliche Gang 5.5 Heitere und trübe Tage 5.6 Nebel 6. SONNENSCHEIN 6.1 Monats- und Jahreswerte 6.2 Tageswerte 6.3 Der tägliche Gang 7. NIEDERSCHLAGSVERHÄLTNISSE 7.1 Monats- und Jahreswerte 7.2 Niederschlagsbereitschaft 7.3 Tageswerte 7.4 Der tägliche Gang 7.5 Häufigkeitsbetrachtungen 7.6 Niederschlags- und Trockenperioden 7.7 Niederschlag und Wind· 7.8 Schneeverhältnisse 7.81 Schneefall und Schneedecke 7.82 Schneehöhe 7.9 Gewitter 8. WINDVERHÄLTNISSE 8.1 Windrichtung 8.2 Windgeschwindigkeit 8.21 Der jährliche Gang 8.22 Häufigkeitsbetrachtungen 8.23 Sturmtage und Windstillen 8.24 Der tägliche Gang 9.ZUSAMMENFASSUNG VERZEICHNIS DER TEXTTABELLEN VERZEICHNIS DER ABBILDUNGEN LITERATURVERZEICHNIS TABELLENANHANG
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  • 18
    Type of Medium: Monograph available for loan
    Pages: Bände (Loseblattsammlung)
    ISBN: 9783963144509 , 3963144505
    Subsequent Title: Fortsetzung von EnEV und Energieausweise ...
    Language: German
    Branch Library: PIK Library
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  • 19
    Journal available for loan
    Journal available for loan
    Tübingen : Mohr Siebeck ; 1.1884 - 48.1931; N.F. 1.1932/33 - 10.1943/44(1945),3; 11.1948/49(1949) -
    Call number: ZS 22.95039
    Type of Medium: Journal available for loan
    Pages: Online-Ressource
    ISSN: 1614-0974 , 0015-2218 , 0015-2218
    Language: German , English
    Note: N.F. entfällt ab 57.2000. - Volltext auch als Teil einer Datenbank verfügbar , Ersch. ab 2000 in engl. Sprache mit dt. Hauptsacht.
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  • 20
    Monograph available for loan
    Monograph available for loan
    Stuttgart : Schweizerbart Science Publishers ; Volume 1, number 1 (1978)-
    Call number: M 18.91571
    Type of Medium: Monograph available for loan
    Pages: 134 Seiten
    ISSN: 2363-7196
    Series Statement: Global tectonics and metallogeny : special issue Vol. 10/2-4
    Classification:
    Tectonics
    Parallel Title: Erscheint auch als Global tectonics and metallogeny
    Language: English
    Location: Upper compact magazine
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  • 21
    Journal available for loan
    Journal available for loan
    München : Altop Verlag ; 2007 -
    Call number: Z 19.92410
    Type of Medium: Journal available for loan
    Pages: 30 cm
    ISSN: 1865-4266
    Former Title: Vorg. Nachhaltiges Wirtschaften in Deutschland
    Language: German
    Note: Ungezählte Beil. ab 2010: Special , Ersch. jährl. 4x
    Branch Library: IASS Library
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  • 22
    Call number: IASS 22.95033
    Type of Medium: Monograph available for loan
    Pages: 378 S , 225 mm x 135 mm
    ISBN: 3899421876 , 978-3-89942-187-3
    Series Statement: Edition panta rei
    Language: German
    Note: Zugl.: Marburg (Lahn), Univ., Habil.-Schr., 2004 u.d.T.: Gutmann, Mathias: Die Medialität des Erfahrens
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  • 23
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 24
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 25
    Publication Date: 2024-02-07
    Description: Biophotonic nanostructures rarely withstand fossilization processes occurring after burial over geologic time. Even more distinctive is a change introduced to the optical properties during diagenetic processes resulting in a different optical appearance. Here, we report and explain the optical appearance of centric diatom frustules obtained from ash-bearing carbonate-cemented concretions on the Greifswalder Oie island (Pomeranian Bay, Germany, southern Baltic Sea). The ultrastructural and mineralogical analysis of the fossil frustules were carried out using electron microscopy techniques and were correlated to the macroscopic and microscopic optical appearance of the frustules before and after acid etching. The unique optical properties of the fossil diatoms were associated with diagenetic nanocrystalline calcite filling the frustules’ areolae. This fill created the macroscopic pale-yellow colour of many frustules, a microscopic iridescence probably associated with diffraction grating behaviour, and microscopic colour rings. The results highlight the unique permineralization process of diatom frustules and might be an addition to the emerging studies on frustule optics and photonics.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 26
    Publication Date: 2024-02-07
    Description: Scientific drilling expeditions offer a unique op- portunity to characterize microbial communities in the sub- surface that have long been isolated from the surface. With subsurface microbial biomass being low in general, biologi- cal contamination from the drilling fluid, sample processing, or molecular work is a major concern. To address this, char- acterization of the contaminant populations in the drilling fluid and negative extraction controls are essential for assess- ing and evaluating such sequencing data. Here, rock cores down to 2250 m depth, groundwater-bearing fractures, and the drilling fluid were sampled for DNA to characterize the microbial communities using a broad genomic approach. However, even after removing potential contaminant popu- lations present in the drilling fluid, notorious contaminants were abundant and mainly affiliated with the bacterial order Burkholderiales. These contaminant microorganisms likely originated from the reagents used for isolating DNA despite stringent quality standards during the molecular work. The detection of strictly anaerobic sulfate reducers such as Candi- datus Desulforudis audaxviator suggested the presence of au- tochthonous deep biosphere taxa in the sequenced libraries, yet these clades represented only a minor fraction of the se- quence counts (〈 0.1 %), hindering further ecological inter- pretations. The described methods and findings emphasize the importance of sequencing extraction controls and can support experimental design for future microbiological stud- ies in conjunction with continental drilling operations.
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  • 27
    Publication Date: 2024-02-07
    Description: Most of in-situ stress data in the Australian continent comes from wellbore stress analysis in deep hydrocarbon reservoirs, and earthquake focal mechanism solutions near the Australian plate boundaries, where geophysical tools facilitate understanding of the present-day stress patterns. This resulted in a paucity of stress information in many other regions such as the northern Bowen Basin, which is an active mining province, but with low seismicity rates and limited deep petroleum exploration. The mining industry runs several hundred kilometres of image logs annually to characterise geotechnical attributes. These logs provide an image from the borehole wall, which facilitates analysis of stress-related borehole deformations for in-situ stress characterisation. This paper examines the orientation of horizontal in-situ stress using different types of image logs in mine boreholes across the northern Bowen Basin. Analyses of 128 km of image logs in 680 vertical boreholes resulted in the interpretation of 9046 pairs of stress-related indicators including 735 drilling induced fractures and 8311 borehole breakouts. Our comprehensive database comprises 890 quality-ranked data records for the orientation of maximum horizontal stress (SHmax), which makes the Bowen Basin as a basin with the highest data density in the world in terms of quality-ranked stress information according to the World Stress Map. Statistical analysis of SHmax orientation reveals that the mean SHmax orientation in northern Bowen Basin is N018◦ ± 16◦. The results show that this orientation is consistent over long distances, which is in contrast with several eastern Australian basins. This uniform stress pattern agrees well with plate-scale geomechanical model predictions, which further highlights the impact of plate boundary forces in the contemporary stress pattern of this region. Detailed image log investigation did not show any systematic rotation of stress; however, some small-scale stress perturbations were observed in the vicinity of sharp stiffness contrasts and geological structures.
    Language: English
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  • 28
    Publication Date: 2024-02-07
    Description: The microbiota is attributed to be important for initial soil formation under extreme climate conditions, but experimental evidence for its relevance is scarce. To fill this gap, we investigated the impact of in situ microbial communities and their interrelationship with biocrust and plants compared to abiotic controls on soil formation in initial arid and semiarid soils. Additionally, we assessed the response of bacterial communities to climate change. Topsoil and subsoil samples from arid and semiarid sites in the Chilean Coastal Cordillera were incubated for 16 weeks under diurnal temperature and moisture variations to simulate humid climate conditions as part of a climate change scenario. Our findings indicate that microorganism-plant interaction intensified aggregate formation and stabilized soil structure, facilitating initial soil formation. Interestingly, microorganisms alone or in conjunction with biocrust showed no discernible patterns compared to abiotic controls, potentially due to watermasking effects. Arid soils displayed reduced bacterial diversity and developed a new community structure dominated by Proteobacteria, Actinobacteriota, and Planctomycetota, while semiarid soils maintained a consistently dominant community of Acidobacteriota and Proteobacteria. This highlighted a sensitive and specialized bacterial community in arid soils, while semiarid soils exhibited a more complex and stable community. We conclude that microorganism-plant interaction has measurable impacts on initial soil formation in arid and semiarid regions on short time scales under climate change. Additionally, we propose that soil and climate legacies are decisive for the present soil microbial community structure and interactions, future soil development, and microbial responses.
    Language: English
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  • 29
    Publication Date: 2024-02-08
    Description: Inland water bodies play a vital role at all scales in the terrestrial water balance and Earth’s climate variability. Thus, an inventory of inland waters is crucially important for hydrologic and ecological studies and management. Therefore, the main aim of this study was to develop a deep learning-based method for inventorying and mapping inland water bodies using the RGB band of high-resolution satellite imagery automatically and accurately. The Sentinel-2 Harmonized dataset, together with ZABAGED-validated ground truth, was used as the main dataset for the model training step. Three different deep learning algorithms based on U-Net architecture were employed to segment inland waters, including a simple U-Net, Residual Attention U-Net, and VGG16-U-Net. All three algorithms were trained using a combination of Sentinel-2 visible bands (Red [B04; 665nm], Green [B03; 560nm], and Blue [B02; 490 nm]) at a 10-meter spatial resolution. The Residual Attention U-Net achieved the highest computational cost due to the increased number of trainable parameters. The VGG16-U-Net had the shortest run time and the lowest number of trainable parameters, attributed to its architecture compared to the simple and Residual Attention U-Net architectures, respectively. As a result, the VGG16-U-Net provided the best segmentation results with a mean-IoU score of 0.9850, a slight improvement compared to other proposed U-Net-based architectures. Although the accuracy of the model based on VGG16-U-Net does not make a difference from Residual Attention U-Net, the computation costs for training VGG16-U-Net were dramatically lower than Residual Attention U-Net.
    Language: English
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  • 30
    Publication Date: 2024-02-08
    Description: Adequate tools for evaluating the Sustainable Intensification of Agriculture (SIA) level are crucial, especially in drylands with limited resources. Based on emergy indices and environmental footprints, We propose an evaluation framework for the case of major crop intensification in Xinjiang, China, and examine the local SIA from 2001 to 2020. The results show that increases in emergy input (EI) of the crop system were achieved with simultaneous increases in water consumption and carbon emissions. The most EI to the system is from economically non-free non-renewable resources (75.1 %), and only 5.4 % from environmentally free renewable resources. The emergy output (EO) of cotton was less than 80 % of wheat and maize, but the carbon footprint (CF) and water footprint (WF) of cotton were much higher than wheat and maize (〉1.18 times and 〉 5.01 times, respectively). We group historical results covering emergy indices, CF, WF, and other production indicators into five dimensions and comprehensively evaluate the level of SIA in Xinjiang according to the changes in the five dimensions. It was found that raising the SIA depended on improving management, productivity, and environmental impact dimension from 2000 to 2005. After 2005, the SIA’s down-turning was due to the trade-offs between management, environmental dimensions, and their indicators and the continuous reduction of sustainability of other dimensions. In addition, the progress and realization of SDG 2, SDG 6, SDG 7, SDG 8, SDG 11, and SDG 12 can effectively improve the SIA. Our study serves as a helpful example for evaluating the level of sustainability of intensive agricultural policies not just in Xinjiang but also in other drylands of the world.
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  • 31
    Publication Date: 2024-02-08
    Description: Rewetting drained peatlands is recognized as a leading and effective natural solution to curb greenhouse gas emissions. However, rewetting creates novel ecosystems whose emission behaviors are not adequately captured by currently used emission factors. These emission factors are applied immediately after rewetting, thus do not reflect the temporal dynamics of greenhouse gas emissions during the period wherein there is a transition to a rewetted steady-state. Here, we provide long-term data showing a mismatch between actual emissions and default emission factors and revealing the temporal patterns of annual carbon dioxide and methane fluxes in a rewetted peatland site in northeastern Germany. We show that site-level annual emissions of carbon dioxide and methane approach the IPCC default emission factors and those suggested for the German national inventory report only between 13 to 16 years after rewetting. Over the entire study period, we observed a source-to-sink transition of annual carbon dioxide fluxes with a decreasing trend of −0.36 t CO2-C ha−1 yr−1 and a decrease in annual methane emissions of −23.6 kg CH4 ha−1 yr−1. Our results indicate that emission factors should represent the temporally dynamic nature of peatlands post-rewetting and consider the effect of site characteristics to better estimate associated annual emissions.
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  • 32
    Publication Date: 2024-02-08
    Description: We present the first sequential structural restoration with flexural backstripping of the Gulf of Mexico US-Mexico conjugate margin salt basin. We construct four large-scale (100s of km) balanced, sequential structural restorations to investigate spatio-temporal patterns of subsidence, geometry of the original salt basin, feedbacks between post-salt structural and stratigraphic evolution, paleo-bathymetry, and crustal configurations. The restorations are based on interpretations of 2D and 3D seismic data, and include sequential sedimentary decompaction, flexural isostatic backstripping, and thermal isostatic corrections. The spatially variable crustal thinning factor is directly measured from seismic data, and lithologic parameters are determined by well penetrations. We present a model for the original salt basin and discuss evidence for and implications of a deep water salt basin setting for the GoM. Our analysis suggests a salt basin that contained ∼1–2 km thick salt in a basin 175–390 km across with ∼1 km of bathymetry after salt deposition. The base of salt is mostly smooth with 〈1 km of local relief in the form of normal faults that disrupt a pre-salt sedimentary section. We find that supra-salt extension and shortening are not balanced, with measurable extension exceeding shortening by 18–30 km on each cross-section. Our subsidence analysis reveals anomalous subsidence totaling 1–2 km during Late Jurassic and Early Cretaceous times that may reflect dynamic topography or depth-dependent thinning. We offer an interpretation of crustal breakup invoking pre-salt clastic sedimentation, salt deposition in a deep water syn-thinning basin, and post-salt lower-crustal exhumation.
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  • 33
    Publication Date: 2024-01-19
    Description: The vapor pressure deficit reflects the difference between how much moisture the atmosphere could and actually does hold, a factor that fundamentally affects evapotranspiration, ecosystem functioning, and vegetation carbon uptake. Its spatial variability and long-term trends under natural versus human-influenced climate are poorly known despite being essential for predicting future effects on natural ecosystems and human societies such as crop yield, wildfires, and health. Here we combine regionally distinct reconstructions of pre-industrial summer vapor pressure deficit variability from Europe’s largest oxygen-isotope network of tree-ring cellulose with observational records and Earth system model simulations with and without human forcing included. We demonstrate that an intensification of atmospheric drying during the recent decades across different European target regions is unprecedented in a pre-industrial context and that it is attributed to human influence with more than 98% probability. The magnitude of this trend is largest in Western and Central Europe, the Alps and Pyrenees region, and the smallest in southern Fennoscandia. In view of the extreme drought and compound events of the recent years, further atmospheric drying poses an enhanced risk to vegetation, specifically in the densely populated areas of the European temperate lowlands.
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  • 34
    Publication Date: 2024-01-19
    Description: The accurate estimation of flood probability is crucial for designing water storage and flood retention structures. However, the assumption of identical distribution in flood samples is unrealistic, given the influence of various flood mechanisms. To address this challenge, we proposed a novel framework based on flood clustering and data pooling that encompasses the key steps such as 1) flood event separation based on a peak-detection flood separation algorithm, 2) grouping flood events using the k-prototypes algorithm, 3) application of the UNprecedented Simulated Extreme ENsemble (UNSEEN) approach to pool reforecast ensemble datasets, and 4) statistical mixing approach to derive common quantiles from all the flood groups. We applied the framework to the Dresden gauge in the Elbe River for a detailed case study. Various tests have been performed to assess the applicability of the UNSEEN approach and the reforecast dataset consistently shows the potential for data pooling. The proposed methodology outperformed the classical approach in terms of goodness-of-fit. The relative difference between the classical and the proposed approach ((classical-proposed)/proposed) for the 100-year return level is 0.16, with a reduction in root mean square error (RMSE) value from 163 to 98 m3/s. Further, replication of the approach to the gauges in North Germany exhibited a relative difference ranging from −0.3 to +0.15 and produced better estimates in terms of RMSE compared with the traditional model. In summary, the proposed framework offers a better estimation of flood probability by addressing the inherent sample inhomogeneity along with the inclusion of unprecedented flood samples.
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  • 35
    Publication Date: 2024-01-19
    Description: African forest are increasingly in decline as a result of land-use conversion due to human activities. However, a consistent and detailed characterization and mapping of land-use change that results in forest loss is not available at the spatial-temporal resolution and thematic levels suitable for decisionmaking at the local and regional scales; so far they have only been provided on coarser scales and restricted to humid forests. Here we present the first high-resolution (5 m) and continental-scale mapping of land use following deforestation in Africa, which covers an estimated 13.85% of the global forest area, including humid and dry forests. We use reference data for 15 different land-use types from 30 countries and implement an active learning framework to train a deep learning model for predicting land-use following deforestation with an F1-score of 84 ± 0.7 for the whole of Africa. Our results show that the causes of forest loss vary by region. In general, small-scale cropland is the dominant driver of forest loss in Africa, with hotspots in Madagascar and DRC. In addition, commodity crops such as cacao, oil palm, and rubber are the dominant drivers of forest loss in the humid forests of western and central Africa, forming an “arc of commodity crops” in that region. At the same time, the hotspots for cashew are found to increasingly dominate in the dry forests of both western and southeastern Africa, while larger hotspots for large-scale croplands were found in Nigeria and Zambia. The increased expansion of cacao, cashew, oil palm, rubber, and large-scale croplands observed in humid and dry forests of western and south-eastern Africa suggests they are vulnerable to future land-use changes by commodity crops, thus creating challenges for achieving the zero deforestation supply chains, support REDD+ initiatives, and towards sustainable development goals.
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  • 36
    Publication Date: 2024-01-19
    Description: Detecting phase arrivals and pinpointing the arrival times of seismic phases in seismograms is crucial for many seismological analysis workflows. For land station data, machine learning methods have already found widespread adoption. However, deep learning approaches are not yet commonly applied to ocean bottom data due to a lack of appropriate training data and models. Here, we compiled an extensive and labeled ocean bottom seismometer (OBS) data set from 15 deployments in different tectonic settings, comprising ∼90,000 P and ∼63,000 S manual picks from 13,190 events and 355 stations. We propose PickBlue, an adaptation of the two popular deep learning networks EQTransformer and PhaseNet. PickBlue joint processes three seismometer recordings in conjunction with a hydrophone component and is trained with the waveforms in the new database. The performance is enhanced by employing transfer learning, where initial weights are derived from models trained with land earthquake data. PickBlue significantly outperforms neural networks trained with land stations and models trained without hydrophone data. The model achieves a mean absolute deviation of 0.05 s for P-waves and 0.12 s for S-waves, and we apply the picker on the Hikurangi Ocean Bottom Tremor and Slow Slip OBS deployment offshore New Zealand. We integrate our data set and trained models into SeisBench to enable an easy and direct application in future deployments.
    Language: English
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  • 37
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    In:  Proceedings of the National Academy of Sciences of the United States of America (PNAS)
    Publication Date: 2024-01-19
    Description: Surface roughness ubiquitously prevails in natural faults across various length scales. Despite extensive studies highlighting the important role of fault geometry in the dynamics of tectonic earthquakes, whether and how fault roughness affects fluid-induced seismicity remains elusive. Here, we investigate the effects of fault geometry and stress heterogeneity on fluid-induced fault slip and associated seismicity characteristics using laboratory experiments and numerical modeling. We perform fluid injection experiments on quartz-rich sandstone samples containing either a smooth or a rough fault. We find that geometrical roughness slows down injection-induced fault slip and reduces macroscopic slip velocities and fault slip-weakening rates. Stress heterogeneity and roughness control hypocenter distribution, frequency–magnitude characteristics, and source mechanisms of injection-induced acoustic emissions (AEs) (analogous to natural seismicity). In contrast to smooth faults where injection-induced AEs are uniformly distributed, slip on rough faults produces spatially localized AEs with pronounced non-double-couple source mechanisms. We demonstrate that these clustered AEs occur around highly stressed asperities where induced local slip rates are higher, accompanied by lower Gutenberg–Richter b-values. Our findings suggest that real-time monitoring of induced microseismicity during fluid injection may allow identifying progressive localization of seismic activity and improve forecasting of runaway events.
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  • 38
    Publication Date: 2024-02-06
    Description: We report uplift and shortening rates from a late Neogene–Pleistocene deformation stage of the frontal fold-thrust belt and adjacent wedge-top in the Principal Cordillera of the southern Central Andes (33-39° SL). A structural model is presented based on integration of surface field data and subsurface 2D seismic sections. Shortening, uplift, and sedimentation rates were calculated from different steps of kinematic modelling. Our structural interpretations and modelling are integrated with new detrital zircon U-Pb geochronology to define a previously overlooked Pleistocene period of orogenic shortening and syntectonic sedimentation in the Malargüe basin. This task was possible due to the dating of three samples yielding between ∼12 and 1 Ma obtained from a 900 m deep well located in the foreland. From stratigraphic correlations, our data records an active Plio-Pleistocene wedge-top depozone coeval with retreat of the volcanism, and the emplacement of retroarc basalts. Structural modelling, together with detrital zircon U-Pb provenance data register shortening producing a foredeep to wedge-top Plio-Pleistocene transition, adjusting and completing the knowledge of the frontal fold-thrust belt and foreland basin in the southern Central Andes.
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  • 39
    Publication Date: 2024-02-06
    Description: Grain boundary networks of quartz, plagioclase and olivine crystal aggregates in metamorphic rocks have been investigated from the nanometer to the millimeter scale by polarized-light microscopy, SEM, and TEM. The studied materials show different grain sizes and experienced different retrograde P-T histories. The aggregates of quartz and plagioclase are traversed by networks of ∼90% continuously open boundaries with μm-sized cavities along the boundaries or at triple junctions. The boundaries are up to ∼500 nm wide open with typically parallel opposing grain faces. Olivine boundaries are filled with serpentine that does not replace olivine but fills the initially open space homogeneously and mostly with random orientation. For quartz there is no correlation between the crystallographic orientation of grain boundaries and their widths. Amongst all samples analyzed, a weak positive correlation exists between grain size and width of open grain boundaries. The application of measured volume changes and elasticity data from the literature to the cooling-decompression paths of the analyzed materials suggests that fracturing with subsequent widening of the grain boundaries starts at temperatures recognizably below the transition from crystal-plastic to brittle behavior of quartz, plagioclase and olivine but not only under surface conditions. The high amount of open boundaries causes an extensive permeability.
    Language: English
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  • 40
    Publication Date: 2024-02-06
    Description: Pit lakes in the ‘anthropogenic lake district’ in the Muskau Arch (western Poland; central Europe) are strongly affected by acid mine drainage (AMD). The studied acidic pit lake, ŁK-61 (pH 〈3), is also exposed to floods due to its location in the flood hazard area, which may significantly influence the geochemical behavior of elements. The elemental compositions of water and lake sediment samples were measured with ICP–OES and ICP–MS. The sediment profile was also examined for 137Cs and 210Po activity concentrations using gamma and alpha spectrometry, respectively. Grain size distribution, mineralogical composition, diatoms, and organic matter content in the collected core were also determined. The key factors responsible for the distribution of selected heavy metals (e.g., Cu, Ni, Pb, Zn) and radioisotopes (137Cs and 210Po) in the bottom sediments of Lake ŁK-61 are their coprecipitation/precipitation with Fe and Al secondary minerals and their sorption onto authigenic and allogenic phases. These processes are likely driven by the lake tributary, which is an important source of dissolved elements. The data also showed that the physiochemical parameters of Lake ŁK-61 water changed during an episodic depositional event, i.e., the flood of the Nysa Łużycka River in the summer of 2010. The flood caused an increase in the water pH, as interpreted from the subfossil diatom studies. The down-core profiles of the studied heavy metal and radionuclide (HMRs) contents were probably affected by this depositional event, which prevented a detailed age determination of the collected lake sediments with 137Cs and 210Pb dating methods. Geochemical modeling indicates that the flood-related shift in the physicochemical parameters of the lake water could have caused the scavenging of dissolved elements by the precipitation of fresh secondary minerals. Moreover, particles contaminated with HMRs have also possibly been delivered by the river, along with the nutrients (e.g., phosphorus and nitrogen).
    Language: English
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  • 41
    Publication Date: 2024-02-06
    Description: Contemporary quantum plasmonics capture subtle corrections to the properties of plasmonic nano-objects in equilibrium. Here, we demonstrate non-equilibrium spill-out redistribution of the electronic density at the ultrafast time scale. As revealed by time-resolved 2D spectroscopy of nanoplasmonic Fe/Au bilayers, an injection of the laser-excited non-thermal electrons induces transient electron spill-out thus changing the plasma frequency. The response of the local electronic density switches the electronic density behavior from spill-in to strong (an order of magnitude larger) spill-out at the femtosecond time scale. The superdiffusive transport of hot electrons and the lack of a direct laser heating indicate significantly non-thermal origin of the underlying physics. Our results demonstrate an ultrafast and non-thermal way to control surface plasmon dispersion through transient variations of the spatial electron distribution at the nanoscale. These findings expand quantum plasmonics into previously unexplored directions by introducing ultrashort time scales in the non-equilibrium electronic systems.
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  • 42
    Publication Date: 2024-02-06
    Description: In the Rafsanjan plain, Iran, the excessive use of groundwater for pistachio irrigation since the 1960s has led to a severe water level decline as well as land subsidence. In this study, the advantages of InSAR analyses and groundwater fow modeling are combined to improve the understanding of the subsurface processes causing groundwater-related land subsidence in several areas of the region. For this purpose, a calibration scheme for the numerical groundwater model was developed, which simultaneously accounts for hydraulic aquifer parameters and sediment mechanical properties of land subsidence and thus considers the impact of water release from aquifer compaction. Simulation results of past subsidence are calibrated with satellite-based InSAR data and further compared with leveling measurements. Modeling results show that land subsidence in this area occurs predominantly in areas with fne-grained sediments and is therefore only partly dependent on groundwater level decline. During the modeling period from 1960 to 2020, subsidence rates of up to 21 cm year−1 are simulated. Due to the almost solely inelastic compaction of the aquifer, this has already led to an irreversible aquifer storage capacity loss of 8.8 km3 . Simulation results of future development scenarios indicate that although further land subsidence cannot be avoided, subsidence rates and the associated aquifer storage capacity loss can be reduced by up to 50 and 36%, respectively, by 2050 through the implementation of improved irrigation management for the pistachio orchards.
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  • 43
    Publication Date: 2024-02-06
    Description: Steranes and hopanes are the biomarkers of eukaryotic sterols and bacterial hopanols. Extracted from sedimentary rock, they are widely used to assess burial temperatures and palaeoecological conditions. The relative proportion of steranes and hopanes is commonly applied as a measure of the flux of eukaryotic versus bacterial biomass into sediments, and the relative abundances of C27, C28 and C29 steranes are proxies for shifts in eukaryote ecology. In Recent sediments, intact sterols provide additional information about particular eukaryotic origins. However, biological lipid distributions are not always recorded faithfully in sediments. Based on observations on modern algae and plants, and on 558 million year old fossil macroalgae from the Ediacaran of the White Sea, we suggest that these biomarker proxies can be severely altered by aerobic microbial reworking, to the extent that a complete loss of primary ecological information may occur. Network analysis on the biomarker data suggests that oxic degradation also affects isomer and homolog distributions of saturated and aromatic steroids, hopanes, cheilanthanes and n-alkanes, generating anomalies in apparent thermal maturity indicators and other proxies. In our dataset, between Ediacaran macroalgae that experienced the least and the most oxic degradation, the absolute concentration of biomarkers decreases 80-fold, and at the same time the proportion of steranes over hopanes decreases by a factor of 82, while the proportion of C29 steranes among total steranes decreases from 91% to 47%. Such redox dependent offsets may explain the recurrently erratic behaviour of numerous biomarker parameters. While these results impart constraints on the interpretation of biomarker distributions, they do provide a tool for evaluating the effects of oxygen exposure and microbial degradation on organic matter preservation in recent and ancient environments and may point towards a solution for the correction of such effects.
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  • 44
    Publication Date: 2024-02-06
    Description: As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them experience frequent inputs of acidic and Mn/metal-rich creek waters due to flushing of acid sulfate soils that are widespread in the creekś catchments. Analyzing existing long-term water chemistry data revealed a strong seasonal variation of Mn loads, with the highest values in spring (after snow melt) and autumn (after heavy rains). We sampled surface waters, suspended particulate matter (SPM), and sediments from the estuarine mixing zones and determined the loads and solid-phase speciation of Mn as well as the composition and metabolic potentials of microbial communities. The results showed that the removal, cycling, and lateral transport of Mn were governed by similar phases and processes in the three estuaries. Manganese X-ray absorption spectroscopy data of the SPM suggested that the removal of Mn was regulated by silicates (e.g., biotite), organically complexed Mn(II), and MnOx (dominated by groutite and phyllomanganates). While the fractional amounts of silicate-bound Mn(II) were overall low and constant throughout the estuaries, MnOx was strongly correlated with the Mn loadings of the SPM and thus the main vector for the removal of Mn in the central and outer parts of the estuaries, along with organically complexed Mn(II). Down estuary, both the fractional amounts and average Mn oxidation state of the MnOx phases increased with (i) the total Mn loads on the SPM samples and (ii) the relative abundances of several potential Mn-oxidizing bacteria (Flavobacterium, Caulobacter, Mycobacterium, and Pedobacter) in the surface waters. These features collectively suggested that the oxidation of Mn, probably mediated by the potential Mn-oxidizing microorganisms, became more extensive and complete towards the central and outer parts of the estuaries. At two sites in the central parts of one estuary, abundant phyllomanganates occurred in the surface sediments, but were converted to surface-sorbed Mn(II) phases at deeper layers (〉3–4 cm). The occurrence of phyllomanganates may have suppressed the reduction of sulfate in the surface sediments, pushing down the methane sulfate transition zone that is typically shallow in estuarine sediments. At the outermost site in the estuary, deposited MnOx were reduced immediately at the water–sediment interface and converted most likely to Mn carbonate. The mobile Mn species produced by the Mn reduction processes (e.g., aqueous Mn(II) and ligand complexed Mn(III)) could partly diffuse into the overlying waters and, together with the estuarine Mn loads carried by the surface waters, transfer large amounts of reactive Mn into open coastal areas and subsequently contribute to Mn shuttling and inter-linked biogeochemical processes over the seafloor. Given the widespread occurrence of acid sulfate soils and other sulfidic geological materials on many coastal plains worldwide, the identified Mn attenuation and transport mechanisms are relevant for many estuaries globally.
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  • 45
    Publication Date: 2024-02-06
    Description: The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including ‘true inoceramids’ and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, S isotopes in carbonate-associated sulfate, along with C and O isotopes in foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50–100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration in seawater. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses
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  • 46
    Publication Date: 2024-02-01
    Description: The structural response to compression of the synthetic high-pressure hydroxide perovskite MgSi(OH)6, the so-called “3.65 Å phase,” has been determined to 8.4 GPa at room temperature using single-crystal XRD in the diamond-anvil cell. Two very similar structures have been determined in space groups P21 and P21/n, for which differences in oxygen donor-acceptor distances indicate that the non-centrosymmetric structure is likely the correct one. This structure has six nonequivalent H sites, of which two are fully occupied and four are half-occupied. Half-occupied sites are associated with a well-defined crankshaft of hydrogen-bonded donor-acceptor oxygens extending parallel to c. Half occupancy of these sites arises from the averaging of two orientations of the crankshaft H atoms (|| ±c) in equal proportions. The P21 and P21/n structures are compared. It is shown that the former is likely the correct space group, which is also consistent with recent spectroscopic studies that recognize six nonequivalent O-H. The structure of MgSi(OH)6 at pressures up to 8.4 GPa was refined in both space groups to see how divergent the two models are. There is a very close correspondence between the responses of the two structures implying that, at least to 8.4 GPa, non-centrosymmetry does not affect compressional behavior. The very different compressional behavior of MgO6 and SiO6 octahedra observed in this study suggests that structural phase transformations or discontinuities likely occur in MgSi(OH)6 above 9 GPa.
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  • 47
    Publication Date: 2024-02-01
    Description: Earth’s magnetic field is a dynamic, changing phenomenon. The geomagnetic field consists of contributions from several sources, of which the main field originating in Earth’s core makes up the bulk. On regional and local scales at Earth’s surface, the lithospheric field can make a substantial contribution to the overall field and therefore needs to be considered in field models. A locally derived regional core field model, named HMOREG, has been shown to give accurate predictions of the southern African region. In this study, a new regional field model called the South African Regional Core and Crust model (SARCC) is introduced. This is the first time that a local lithospheric model, estimated by employing the revised spherical cap harmonic analysis modelling method, has been combined with the core component of CHAOS-6, a global field model. It is compared here with the existing regional field model as well as with global core field models. The SARCC model shows small-scale variations that are not present in the other three models. Including a lithospheric magnetic field component likely contributed to the better performance of the SARCC model when compared to other global and local field models. The SARCC model showed a 33% reduction in error compared to surface observations obtained from field surveys and INTERMAGNET stations in the Y component, and HMOREG showed a 7% reduction in error compared to the global field models. The new model can easily be updated with global geomagnetic models that incorporate the most recent, state-of-the-art core and magnetospheric field models.
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  • 48
    Publication Date: 2024-02-01
    Description: The Combination Service for Time-variable Gravity fields (COST-G) operationally provides combinations of monthly Earth gravity field models derived from observations of the microwave ranging instrument of the GRACE Follow-on (GRACE-FO) satellite mission, applying the quality control and combination methodology originally developed by the Horizon 2020 project European Gravity Service for Improved Emergency Management for the data of the GRACE satellites. In the frame of the follow-up Horizon 2020 project Global Gravity-based Groundwater Product (G3P), the GRACE-FO combination is used to derive global grids of groundwater storage anomalies. To meet the user requirements and achieve optimal signal-to-noise ratio, the combination has been further developed and extended to incorporate: • new time-series based on the alternative accelerometer transplant product generated in the frame of the project by the Institute of Geodesy at the Graz University of Technology, which specifically improves the estimation of the C30 coefficient and also reduces the noise at medium to short wavelengths, and • the new time-series AIUB–GRACE-FO–RL02 of monthly GRACE-FO gravity fields, which is derived at the Astronomical Institute of the University of Bern by applying empirical noise modelling techniques. The COST-G quality control confirms the consistency of the contributing GRACE-FO time-series concerning the signal amplitude of seasonal hydrology in large river basins and the secular mass change in polar regions, but it also indicates rather diverse noise characteristics. The difference in the noise levels is taken into account in the combination process by relative weights derived by variance component estimation on the solution level. The weights are expected to be inverse proportional to the noise levels of the individual gravity field solutions. However, this expectation is violated when applying the weighting scheme as developed for the GRACE combination. The reason is found in the high-order coefficients of the gravity field, which are poorly determined from the low–low range-rate observations due to the observation geometry and suffer from aliasing due to the malfunctioning accelerometer onboard one of the GRACE-FO satellites. Hence, for the final G3P-combination a revised weighting scheme is applied where the gravity field coefficients beyond order 60 are excluded from the determination of the weights. The quality of the combined gravity fields is assessed by comparison of the noise content and the signal-to-noise ratio with the individual time-series. Independent validation is provided by the COST-G validation centre at the GFZ German Research Centre for Geosciences, where orbit fits of the low-flying Gravity and steady-state Ocean Circulation Explorer satellite are performed that confirm the high quality of the combined GRACE-FO gravity fields. By the end of the G3P project, the new combination scheme is implemented by COST-G as the new COST-G–GRACE-FO–RL02 and continued to be used for the operational GRACE-FO combination.
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  • 49
    Publication Date: 2023-10-20
    Description: Application of Aquifer Thermal Energy Storage with High Temperatures (HT-ATES) ranging from 60–90 is a promising technique to store large amounts of energy in urban areas. However, these areas typically lack information on hydrogeological and thermal parameters of the subsurface to determine the potential for energy storage. Moreover, conventional exploration methods as pumping tests do not account for the variation in density caused by the high temperature gradients or changes in salinity as encountered in HT-ATES operation. The objective of this study is therefore to develop best practices for characterizing the hydrogeological and thermal properties of groundwater wells and their surrounding formation that determine the potential performance of HT-ATES-systems. In addition to conventional pumping tests, a set of Push–Pull tracer Tests (PPTs) with cold and hot water are proposed and scrutinized using Berlin as case study. There, the research well Gt BChb 1/2015, which is characterized by a reservoir temperature of 17 at a depth between 220 und 230 m below ground surface was tested. In 2017, seven Slug-Withdrawal Tests (SWTs), a Step-Rate-Test (SRT), a production tests, and two Push–Pull tracer Tests (PPTs) with hot and cold water were performed during a period of 40 days. These tests were accompanied by Distributed-Temperature-Sensing (DTS) monitoring. The temperature measurements provide indications of injection areas based on the warmback period during a PPT with 81 hot water. The determined aquifer transmissibility , the related Productivity Index (), and maximum flow rates of about indicate that the aquifer has potential for HT-ATES. However, the PPT and the DTS monitoring revealed cross flow between the target aquifer and an overlying aquifer. Thus, a new well with a design avoiding cross flow is required to utilize the aquifer’s energy storage potential. A set of best practices for characterizing HT-ATES potential was derived from the experiences in this study.
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  • 50
    Publication Date: 2023-10-11
    Description: At the geothermal research platform Gross Schönebeck (NE German Basin), we analysed 3-D seismic reflection data to determine the degree and direction of azimuthal velocity anisotropy which is interpreted as the effect of sub-vertical fracturing. Above the Zechstein salt, the observed anisotropy roughly correlates to fault structures formed by an upwelling salt pillow. Below the salt, faults are not obvious and the direction of less pronounced anisotropy and interpreted fracturing follows the trend of the regional stress field. The fracturing in an extensional setting above salt pillows may cause higher permeability and better conditions for geothermal exploitation.
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  • 51
    Publication Date: 2024-01-18
    Description: Stratigraphy along the Brazilian Equatorial Margin is a crucial guide to the geodynamic history of rifting of Pangea and formation of the South Atlantic Ocean. Understanding the evolution of the Brazilian Equatorial Margin, which intersects the Saint Paul and Romanche Fracture Zones on the western margin of South Atlantic Ocean, is also key for reconstructing eustatic histories and natural resource exploration. In this study, we quantify the stratigraphic and subsidence histories of three sedimentary basins—Barreirinhas, Ceará, Potiguar—that sit within the margin. Stratigraphy was mapped using ca. 900-line-km of two-dimensional seismic data. Biostratigraphic and check-shot data from 23 wells drilled on the continental shelf, slope and in the distal parts of these basins were used to date and depth-convert stratigraphy. Check-shot data were also used to parameterise compaction. The mapped stratigraphy was backstripped to calculate subsidence histories for the basins. Subsidence curves were decompacted, water-loaded and corrected for palaeo-water depths using biostratigraphic data from well reports. The mapped stratigraphy of the Barreirinhas and Ceará Basins and theoretical subsidence curves indicate that stretching factors did not exceed 1.6. These values suggest that these basins can be regarded as failed rifts. In contrast, more distal stratigraphy mapped in the Potiguar Basin to the south indicates that it stretched by a factor of 5–6. Calculated subsidence histories indicate that this basin formed primarily because of Cretaceous rifting and Cretaceous to Recent post-rift thermal sag, with amplitudes governed by the amount of initial stretching.
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  • 52
    Publication Date: 2024-01-18
    Description: The Jinsha River basin in the upper reaches of the Yangtze River in China is prone to strong geological activities, with numerous large-scale landslides along its banks that can potentially trigger a cascade of flood hazards. Recent seismic events such as the Wenchuan and Luding earthquakes have heightened the likelihood of landslide collapses along the slopes of the Jinsha River, thereby increasing the risk of a large-scale landslide-dam-break-flood hazard chain. Among these landslides, the ancient Woda landslide is currently in a state of slow deformation, and if reactivated, it can potentially obstruct the river and trigger catastrophic outburst floods. This study uses the integrated continuum method to simulate the dynamic processes associated with large-scale slope failures and the formation of landslide dams. Furthermore, the outburst flood resulting from the dam breach is modeled by combining the dammed lake flow model and the shallow water equation, allowing for the simulation of long-distance flood propagation. The findings indicate that the Woda landslide has the potential to create a dam of approximately 68.1 m in height, with a corresponding dammed-lake volume of about 7.10 × 108 m3. The peak flow rate of the resulting outburst flood can reach 4.4 × 104 m3/s, leading to an extensive impact zone reaching 140 km downstream. This flood inundates several downstream villages, towns, and even the Sichuan-Tibet Railway which is under construction. Moreover, the study reveals that the resistance coefficient of landslides significantly influences the entire hazard chain evolution process. Lowering the resistance coefficient of landslides leads to a considerable increase in the height of the landslide dam, amplification of the peak flow rate of the outburst flood, and an elevated risk for downstream elements situated at greater distances.
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  • 53
    Publication Date: 2024-01-18
    Description: Forecasting eruptions is a fundamental goal of volcanology. However, difficulties in identifying eruptive precursors, fragmented approaches and lack of resources make eruption forecasting difficult to achieve. In this Review, we explore the first-order scientific approaches that are essential to progress towards forecasting the time and location of magmatic eruptions. Forecasting in time uses different monitoring techniques, depending on the conduit-opening mode. Ascending magma can create a new conduit (closed-conduit eruptions), use a previously open conduit (open-conduit eruptions) or flow below a solidified magma plug (semi-open-conduit eruptions). Closed-conduit eruptions provide stronger monitoring signals often detected months in advance, but they commonly occur at volcanoes with poorly known pre-eruptive behaviour. Open-conduit eruptions, associated with low-viscosity magmas, provide more subtle signals often detected only minutes in advance, although their higher eruption frequency promotes more testable approaches. Semi-open-conduit eruptions show intermediate behaviours, potentially displaying clear pre-eruptive signals days in advance and often recurring repeatedly. However, any given volcano can experience multiple conduit-opening modes, sometimes simultaneously, requiring combinations of forecasting approaches. Forecasting the location of vent opening relies on determining the stresses controlling magma propagation, deformation and seismic monitoring. The use of physics-based models to assimilate monitoring data and observations will substantially improve forecasting, but requires a deeper understanding of pre-eruptive processes and more extensive monitoring data.
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  • 54
    Publication Date: 2024-01-18
    Description: Beryllium isotopes have emerged as a quantitative tracer of continental weathering, but accurate and precise determination of the cosmogenic 10Be and stable 9Be in seawater is challenging, because seawater contains high concentrations of matrix elements but extremely low concentrations of 9Be and 10Be. In this study, we develop a new, time-efficient procedure for the simultaneous preconcentration of 9Be and 10Be from (coastal) seawater based on the iron co-precipitation method. The concentrations of 9Be, 10Be, and the resulting 10Be/9Be ratio for Changjiang Estuary water derived from the new procedure agree well with those obtained from the conventional procedure requiring separate preconcentration for 9Be and 10Be determinations. By avoiding the separate preconcentration, our newly developed procedure contributes toward more time-efficient handling of samples, less sample cross-contamination, and a more reliable 10Be/9Be ratio. Prior to this, we validated the iron co-precipitation method using artificial seawater and natural water samples from the Amazon Estuary regarding: (1) the “matrix effect” for Be analysis, (2) its extraction efficiency for pg g−1 levels Be in the presence and absence of organic matter, and (3) the data comparability with another preconcentration method. We calculated that for the determination of 9Be and 10Be in most open ocean seawater with typical 10Be concentrations of 〉 500 atoms g−1, good precisions (〈 5%) can be achieved using less than 3 liters of seawater compared to more than 20 liters routinely used previously. Even for coastal seawater with extremely low 10Be concentration (e.g., 100 atoms g−1), we estimate a maximum amount of 10 liters to be adequate.
    Language: English
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  • 55
    Publication Date: 2024-01-18
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  • 56
    Publication Date: 2024-01-18
    Description: Accurate age estimates are crucial for assessing the life-histories of fish and providing management advice, but validation studies are rare for many species. We corroborated age estimates with annual cycles of oxygen isotopes (δ18O) in otoliths of 86 northern pike (Esox lucius) from the southern Baltic Sea, compared results with visual age estimates from scales and otoliths, and assessed bias introduced by different age-estimation structures on von Bertalanffy growth models and age-structured population models. Age estimates from otoliths were accurate, while age estimates from scales significantly underestimated the age of pike older than 6 years compared to the corroborated reference age. Asymptotic length () was larger, and the growth coefficient was lower for scale ages than for corroborated age and otolith age estimates. Consequentially, scale-informed population models overestimated maximum sustainable yield (), biomass at (), relative frequency of trophy fish (), and optimal minimum length limit but underestimated fishing mortality at (). Using scale-based ages to inform management regulations for pike may therefore result in conservative management and lost yield. The overestimated asymptotic length may instill unrealistic expectations of trophy potential in recreational anglers targeting large pike, while the overestimation in MSY would cause unrealistic expectations of yield potential in commercial fishers.
    Language: English
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  • 57
    Publication Date: 2023-12-22
    Description: Monitoring urban heat island (UHI) effect is critical because it causes health problems and excessive energy consumption more energy when cooling buildings. In this study, we propose an approach for UHI monitoring by fusing data from ground-based global navigation satellite system (GNSS), space-based GNSS radio occultation (RO), and radiosonde. The idea of the approach is as follows: First, the first and second grid tops are defined based on historical RO and radiosonde observations. Next, the wet refractivities between the first and second grid tops are fitted to higher-order spherical harmonics and they are used as the inputs of GNSS tomography. Then, the temperature and water vapor partial pressure are estimated by using best search method based on the tomography-derived wet refractivity. In the end, the UHI intensity is evaluated by calculating the temperature difference between the urban regions and nearby rural regions. Feasibility of the UHI intensity monitoring approach was evaluated with GNSS RO and radiosonde data in 2010–2019, as well as ground-based GNSS data in 2020 in Hong Kong, China, by taking synoptic temperature data as reference. The result shows that the proposed approach achieved an accuracy of 1.2 K at a 95% confidence level.
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  • 58
    Publication Date: 2023-12-18
    Description: Inorganic geochemistry is a powerful tool in paleolimnology. It has become one of the most commonly used techniques to analyze lake sediments, particularly due to the development and increasing availability of XRF core scanners during the last two decades. It allows for the reconstruction of the continuous processes that occur in lakes and their watersheds, and it is ideally suited to identify event deposits. How earth surface processes and limnological conditions are recorded in the inorganic geochemical composition of lake sediments is, however, relatively complex. Here, we review the main techniques used for the inorganic geochemical analysis of lake sediments and we offer guidance on sample preparation and instrument selection. We then summarize the best practices to process and interpret bulk inorganic geochemical data. In particular, we emphasize that log-ratio transformation is critical for the rigorous statistical analysis of geochemical datasets, whether they are obtained by XRF core scanning or more traditional techniques. In addition, we show that accurately interpreting inorganic geochemical data requires a sound understanding of the main components of the sediment (organic matter, biogenic silica, carbonates, lithogenic particles) and mineral assemblages. Finally, we provide a series of examples illustrating the potential and limits of inorganic geochemistry in paleolimnology. Although the examples presented in this paper focus on lake and fjord sediments, the principles presented here also apply to other sedimentary environments.
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  • 59
    Publication Date: 2023-12-19
    Description: The Altiplano-Puna Plateau of the Central Andes hosts numerous lakes, playa-lakes, and salars with a great diversity and abundance of carbonates forming under extreme climatic, hydrologic, and environmental conditions. To unravel the underlying processes controlling the formation of carbonates and their geochemical signatures in hypersaline systems, we investigated coupled brine-carbonate samples in a high-altitude Andean lake using a wide suite of petrographic (SEM, XRD) and geochemical tools (δ2H, δ18O, δ13C, δ11B, major and minor ion composition, aqueous modelling). Our findings show that the inflow of hydrothermal springs in combination with strong CO2 degassing and evaporation plays an important role in creating a spatial diversity of hydro-chemical sub-environments allowing different types of microbialites (microbial mounds and mats), travertines, and fine-grained calcite minerals to form. Carbonate precipitation occurs in hot springs triggered by a shift in carbonate equilibrium by hydrothermal CO2 degassing and microbially-driven elevation of local pH at crystallisation. In lakes, carbonate precipitation is induced by evaporative supersaturation, with contributions from CO2 degassing and microbiological processes. Lake carbonates largely record the evaporitic enrichment (hence salinity) of the parent water which can be traced by Na, Li, B, and δ18O, although other factors (such as e.g., high precipitation rates, mixing with thermal waters, groundwater, or precipitation) also affect their signatures. This study is of significance to those dealing with the fractionation of oxygen, carbon, and boron isotopes and partitioning of elements in natural brine-carbonate environments. Furthermore, these findings contribute to the advancement in proxy development for these depositional environments.
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  • 60
    Publication Date: 2024-01-16
    Description: Arctic warming increases the degradation of permafrost soils but little is known about floodplain soils in the permafrost region. This study quantifies soil organic carbon (SOC) and soil nitrogen stocks, and the potential CH4 and CO2 production from seven cores in the active floodplains in the Lena River Delta, Russia. The soils were sandy but highly heterogeneous, containing deep, organic rich deposits with 〉60% SOC stored below 30 cm. The mean SOC stocks in the top 1 m were 12.9 ± 6.0 kg C m−2. Grain size analysis and radiocarbon ages indicated highly dynamic environments with sediment re-working. Potential CH4 and CO2 production from active floodplains was assessed using a 1-year incubation at 20°C under aerobic and anaerobic conditions. Cumulative aerobic CO2 production mineralized a mean 4.6 ± 2.8% of initial SOC. The mean cumulative aerobic:anaerobic C production ratio was 2.3 ± 0.9. Anaerobic CH4 production comprised 50 ± 9% of anaerobic C mineralization; rates were comparable or exceeded those for permafrost region organic soils. Potential C production from the incubations was correlated with total organic carbon and varied strongly over space (among cores) and depth (active layer vs. permafrost). This study provides valuable information on the carbon cycle dynamics from active floodplains in the Lena River Delta and highlights the key spatial variability, both among sites and with depth, and the need to include these dynamic permafrost environments in future estimates of the permafrost carbon-climate feedback.
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  • 61
    Publication Date: 2024-01-16
    Description: This contribution is presenting a multidisciplinary investigation of heterogeneities in a clay rock formation, based on seismic tomography, logging and core analysis, as a reconnaissance study for a diffusion experiment. Diffusion experiments in clay rock formations provide crucial experimental data on diffusive transport of radionuclides (RN) in extremely low hydraulic conductivity media. Previous diffusion experiments, conducted, for example, in the Mont Terri underground rock laboratory within the relatively homogeneous shaly facies of Opalinus Clay, and modelling studies of these experiments have demonstrated that the clay rock could sufficiently well be described as a homogeneous anisotropic medium. For other lithofacies, characterized by larger heterogeneity, such simplification may be unsuitable, and the description of heterogeneity over a range of scales will be important. The sandy facies of the Opalinus Clay exhibits a significantly more pronounced heterogeneity compared to the shaly facies, and a combined characterization and RN diffusion study has been initiated to investigate various approaches of heterogeneity characterization and subsequent diffusion in a heterogeneous environment. As an initial step, two inclined exploratory boreholes have been drilled to access the margins of the experiment location. These boreholes have been used to acquire a cross-hole tomographic seismic data set. Optical, natural gamma and backscattering logging were applied and rock cores were analysed. The integrated results of these investigations allowed the identification of an anomalous brighter layer within the investigated area of the sandy facies of approximately 1 m thickness and with its upper bound at roughly 10 m depth within the inclined exploratory wells. Mineralogical analyses revealed only slight variations throughout the rock cores and indicated that the anomalous layer exhibited a slightly higher quartz content, and locally significantly higher calcite contents, accompanied by a lower content of clay minerals. The anomalous layer was characterized by reduced natural gamma emissions, due to the lower clay content, and increased neutron backscattering likely indicating an increased porosity. Seismic P-wave velocities, derived from anisotropic tomography, exhibited a maximal gradient near the top of this layer. The transition from the overlaying darker rock matrix into this layer has been identified as an appropriate location for the setup of a tracer diffusion experiment in a heterogeneous environment.
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  • 62
    Publication Date: 2024-01-16
    Description: The joint ESA/NASA Mass-change And Geosciences International Constellation (MAGIC) has the objective to extend time-series from previous gravity missions, including an improvement of accuracy and spatio-temporal resolution. The long-term monitoring of Earth’s gravity field carries information on mass change induced by water cycle, climate change and mass transport processes between atmosphere, cryosphere, oceans and solid Earth. MAGIC will be composed of two satellite pairs flying in different orbit planes. The NASA/DLR-led first pair (P1) is expected to be in a near-polar orbit around 500 km of altitude; while the second ESA-led pair (P2) is expected to be in an inclined orbit of 65°–70° at approximately 400 km altitude. The ESA-led pair P2 Next Generation Gravity Mission shall be launched after P1 in a staggered manner to form the MAGIC constellation. The addition of an inclined pair shall lead to reduction of temporal aliasing effects and consequently of reliance on de-aliasing models and post-processing. The main novelty of the MAGIC constellation is the delivery of mass-change products at higher spatial resolution, temporal (i.e. subweekly) resolution, shorter latency and higher accuracy than the Gravity Recovery and Climate Experiment (GRACE) and Gravity Recovery and Climate Experiment Follow-On (GRACE-FO). This will pave the way to new science applications and operational services. In this paper, an overview of various fields of science and service applications for hydrology, cryosphere, oceanography, solid Earth, climate change and geodesy is provided. These thematic fields and newly enabled applications and services were analysed in the frame of the initial ESA Science Support activities for MAGIC. The analyses of MAGIC scenarios for different application areas in the field of geosciences confirmed that the double-pair configuration will significantly enlarge the number of observable mass-change phenomena by resolving smaller spatial scales with an uncertainty that satisfies evolved user requirements expressed by international bodies such as IUGG. The required uncertainty levels of dedicated thematic fields met by MAGIC unfiltered Level-2 products will benefit hydrological applications by recovering more than 90 per cent of the major river basins worldwide at 260 km spatial resolution, cryosphere applications by enabling mass change signal separation in the interior of Greenland from those in the coastal zones and by resolving small-scale mass variability in challenging regions such as the Antarctic Peninsula, oceanography applications by monitoring meridional overturning circulation changes on timescales of years and decades, climate applications by detecting amplitude and phase changes of Terrestrial Water Storage after 30 yr in 64 and 56 per cent of the global land areas and solid Earth applications by lowering the Earthquake detection threshold from magnitude 8.8 to magnitude 7.4 with spatial resolution increased to 333 km.
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  • 63
    Publication Date: 2024-01-16
    Description: Accurate assessment of the rate and state friction parameters of rocks is essential for producing realistic earthquake rupture scenarios and, in turn, for seismic hazard analysis. Those parameters can be directly measured on samples, or indirectly based on inversion of coseismic or postseismic slip evolution. However, both direct and indirect approaches require assumptions that might bias the results. Aiming to reduce the potential sources of bias, we take advantage of a downscaled analog model reproducing megathrust earthquakes. We couple the simulated annealing algorithm with quasi-dynamic numerical models to retrieve rate and state parameters reproducing the recurrence time, rupture duration and slip of the analog model, in the ensemble. Then, we focus on how the asperity size and the neighboring segments' properties control the seismic cycle characteristics and the corresponding variability of rate and state parameters. We identify a tradeoff between (a–b) of the asperity and (a–b) of neighboring creeping segments, with multiple parameter combinations that allow mimicking the analog model behavior. Tuning of rate and state parameters is required to fit laboratory experiments with different asperity lengths. Poorly constrained frictional properties of neighboring segments are responsible for uncertainties of (a–b) of the asperity in the order of per mille. Roughly one order of magnitude larger uncertainties derive from asperity size. Those results provide a glimpse of the variability that rate and state friction estimates might have when used as a constraint to model fault slip behavior in nature.
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  • 64
    Publication Date: 2024-01-15
    Description: Situated within a 1.07 million-year-old meteorite crater, Lake Bosumtwi in Ghana stands as a pivotal location for comprehending climatic, ecological and environmental fluctuations within the sub-Saharan region of West Africa. The region's susceptibility to seasonal environmental shifts and climate oscillations is heightened by the annual movements of the tropical rain belt driven by atmospheric circulation. Yet, there is no satisfying age-depth model available for the entire sedimentary sequence strongly limiting our understanding of changes in this circulation pattern and associated (broad-scale) environmental responses during the last million years in the local to regional context of Lake Bosumtwi. To overcome this, we statistically examine the cyclicity in total natural gamma ray (NGR) data on a core from the lake's centre and create a cyclostratigraphic age-depth model. The calculated maximum age of 946 ka agrees well with the meteorite impact age (∼10 % offset). In order to refine this purely statistical approach, we also perform a correlative age-depth model using 33 tie points accounting for the complexity of climatic and environmental imprints to the NGR record that may exceed direct insolation related effects. Special attention is paid to the core's robustly dated (14C, OSL, U/Th) uppermost part covering the last 200 ka. Here, high NGR and co-varying K counts coincide with warm periods (except of the water-saturated and unconsolidated Holocene part) and the inverse for glacials and stadials. Based on this, we define tie points for correlating our NGR data to the age-depth model of a NE Atlantic SST record. Comparing our results to the correlation target, other global climate records and Sahara dust flux data reveals striking similarities and supports a proxy understanding with increased in wash of K-enriched terrigenous material from the crater rims in warm and moist periods (high NGR) and K-depleted dust input in stadials possibly contributing to low NGR values in addition to reduced input of K-enriched sediments from the crater rims. Our correlative age model results in precession amplitudes matching eccentricity well, providing further support especially because an over-tuning is unlikely with the used 33 tie points. Overall we provide crucial chronological context to numerous datasets along with environmental constrains that can be used to study the potential habitat availability of early anatomically modern humans in West Africa.
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  • 65
    Publication Date: 2024-01-15
    Description: The evolution of the local stress field of faults under tectonic stresses is crucial to predict earthquakes. In this study, we investigated the stress sensitivity of an analogue fault model with dimensions of 2 m × 1 m × 1 m, prepared from cement, gypsum, river sand, putty powder, and borax mixture. The angle between the fault strike and the maximum stress direction was varied, and the variation in the stress near the analogue fault (area 1200 × 400 mm; width 5 mm) was determined. The crack growth law of the analogue fault was found to be consistent with a simple Riedel shear model. A main strike-displacement zone was formed, and its direction was parallel to that of the analogue fault. Fault development was described by three stages based on stress–strain relationships: a nucleus stage, a stable growth, and an unstable growth stage. The deflection angle (the deflection angle of the local principal stresses) range of the local stress field was (− 45°, 45°), and it varied most significantly in the nucleus stage. The closer to the fault, the greater the variation range in the deflection angle. The variation range was greater in the fault compression quadrants than in the dilatation quadrants. The correlation between the deflection angle and the relative deformation velocity of the fault was stronger in the stable growth stage than in the other stages. In this stage, the angle–deformation–velocity correlation could be well fitted using a logistic trend model. These findings can be of importance to better understand the nucleation and mechanisms of fault slip-induced earthquakes under varying fault-strike-stress conditions.
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  • 66
    Publication Date: 2024-01-15
    Description: The yield and composition of tar depending on coal rank and pressure during underground coal gasification (UCG) were studied. Two coals were used in a series of ex-situ UCG experiments: a Welsh semi-anthracite (Six Feet) and a Polish bituminous coal (Wesoła). Four high-pressure gasification trials under two distinct pressure regimes (20 and 40 bar) were conducted. The tar samples were collected directly from the reactor outlet. The following groups of compounds were analysed by use of gas chromatography (GC-MS): light monoaromatic hydrocarbons (BTEX – benzene, toluene, ethylbenzene and xylenes), polycyclic aromatic hydrocarbons (PAHs) and phenols. A series of gasification experiments revealed significant differences in tar yields and composition depending on the coal rank and gasification pressure. Significant decreases in tar contents were observed with the increase in gasification pressure from 20 to 40 bar for both coals. The total yields of the analysed tar components per kg of gasified coal were 2.58 g and 0.41 g for the experiments conducted on the Six Feet samples at 20 bar and 40 bar, respectively. The corresponding values for the Wesoła coal amounted to 5.48 g and 0.95 g. In all experiments, BTEX was a dominant group of tar components, constituting 69–86 % of the total tar yield within the tested range of compounds. The present study further proves that gasification pressure has a significant effect on the chemical composition of the produced UCG tars for both coal samples under study.
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  • 67
    Publication Date: 2024-01-15
    Description: Traditionally, the emplacement of the Large Igneous Provinces (LIPs) is considered to have caused continental break-up. However, this does not always seem to be the case, as illustrated by, for example, the Siberian Traps, one of the most voluminous flood basalt events in Earth history, which was not followed by lithospheric rupture. Moreover, the classical model of purely active (plume-induced) rifting and continental break-up often fails to do justice to widely varying tectonic impacts of Phanerozoic LIPs. Here, we show that the role of the LIPs in rupture of the lithosphere ranges from initial dominance (e.g., Deccan LIP) to activation (e.g., Central Atlantic Magmatic Province, CAMP) or alignment (e.g., Afar LIP). A special case is the North Atlantic Igneous Province (NAIP), formed due to the “re-awakening” of the Iceland plume by the lateral propagation of the spreading ridge and the simultaneous approach of the plume conduit to adjacent segments of the thinner overlying lithosphere. The proposed new classification of LIPs may provide useful guidance for future research, particularly with respect to some inherent limitations of the common paradigm of purely passive continental break-up and the assumption of a direct link between internal mantle dynamics and the timing of near-surface magmatism.
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  • 68
    Publication Date: 2024-01-15
    Description: In this article, a high-resolution acoustic emission sensor, accelerometer, and broadband seismometer array data set is made available and described in detail from in situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility of generating multi-stage heat exchangers in a controlled way superiorly to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in situ stress and is monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the nearby tunnel system. Three different fluid injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30m30m30m at depth. We collected geological data from core and borehole logs, fracture inspection data from an impression packer, and acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication are important steps in both upscaling laboratory tests and downscaling field tests in granitic rock in the framework of enhanced geothermal system research. Data described in this paper can be accessed at GFZ Data Services under https://doi.org/10.5880/GFZ.2.6.2023.004 (Zang et al., 2023).
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  • 69
    Publication Date: 2024-01-15
    Description: Probing source mechanisms of natural and induced earthquakes is a powerful tool to unveil associated rupture kinematics. The source processes of failure and slip instability driven by stress loading are affected by fault geometry, but the source ruptures of injection-induced seismicity in relation to fault structures and local stress states remain poorly understood. We have conducted a series of fault reactivation and slip experiments on sandstone samples containing faults with different surface roughness (smooth saw-cut fault and fractured rough fault). We impose progressive fluid injection to induce fault slip, and simultaneously monitor the associated acoustic emission (AE) activity. Using high-resolution AE recordings, we perform full moment tensor inversion of all located AE sources, and investigate the changes of AE source characteristics associated with induced fault slip and their relation to fault roughness. For the complex and rough fault, we observe significant non-double-couple components of AE sources and a high degree of focal mechanism heterogeneity. The temporal changes of AE mechanisms associated with injection-induced fault slip on the smooth fault reveal increasing proportions of double-couple components and decreasing variability of AE focal mechanisms when approaching the onset of slip events. The observed inconsistency between the nodal planes of AE sources and the macroscopic fault plane orientation is attributed to the development of secondary fracture networks surrounding the principal slip surface. We analyze changes in the magnitude-frequency characteristics and source mechanisms of AEs with fault-normal distance, showing that for the smooth (mature) fault, Gutenberg–Richter b-value of on-fault seismicity is lower and focal mechanisms are less heterogeneous, compared to off-fault seismicity. Our results emphasize the important role of roughness-related changes in local fault geometry and associated stress heterogeneity for source mechanisms and rupture kinematics of injection-induced seismicity.
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  • 70
    Publication Date: 2023-12-21
    Description: Interface problems exist widely in various engineering problems and their high-precision simulation is of great importance. A new computational approach for dealing with interface problems is proposed based on the recently developed integral-generalized finite difference (IGFD) scheme. In this method, the research domain is divided into several subdomains by interfaces, and discretization schemes are established independently in each subdomain. A new cross-subdomain integration scheme is introduced to connect these subdomains. Several two-dimensional elasticity models containing material interfaces are studied to test the effectiveness of the proposed method. The results show that the recently proposed approach without the help of discontinuous functions or auxiliary equations that are commonly used in other numerical methods (e.g., extended finite element method and boundary element method) enables obtaining high accuracy and efficiency in interface problems. The proposed method has great potential in the application of material interface problems in solid mechanics and, furthermore, weak discontinuity problems in various fields.
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  • 71
    Publication Date: 2023-12-21
    Description: In space geodetic techniques, the mapping functions (MFs) provide the relationship between zenith and slant tropospheric delays. The MFs are determined under the assumption of spherically layered atmosphere. However, the atmosphere is not spherically layered, and the asymmetry should be considered. Therefore, tropospheric gradients are taken into account. Nevertheless, tropospheric gradients alone can not fully represent the deviation from a spherically layered atmosphere, and hence cm level errors arise especially for low elevation angles. In this study, we present new approaches to modify the wet MF to reduce mismodelling of tropospheric delays. The delays in the study were calculated using ray-tracing algorithm based on ECMWF’s ERA5 dataset. We first analyzed the performances of the new approaches. Then, two Precise Point Positioning (PPP) simulation studies and a real case study were carried out for two different regions namely Germany and Türkiye. According to the results, the proposed approaches reduce the modelling errors up to by a factor 6 for both regions. Besides, simulation studies show that the approaches improve the accuracies of the ZTDs and heights. In the practical application however, we could not find a clear improvement in the PPP analyze and this might be related to the ERA5 which can not be regarded error-free.
    Language: English
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  • 72
    Publication Date: 2024-01-24
    Description: Anthropogenic climate change drives extreme weather events, leading to significant consequences for both society and the environment. This includes damage to road infrastructure, causing disruptions in transportation, obstructing access to emergency services, and hindering humanitarian organizations after natural disasters. In this study, we develop a novel method for analyzing the impacts of natural hazards on transportation networks rooted in the gravity model of travel, offering a fresh perspective to assess the repercussions of natural hazards on transportation network stability. Applying this approach to the Ahr valley flood of 2021, we discovered that the destruction of bridges and roads caused major bottlenecks, affecting areas considerably distant from the flood’s epicenter. Furthermore, the flood-induced damage to the infrastructure also increased the response time of emergency vehicles, severely impeding the accessibility of emergency services. Our findings highlight the need for targeted road repair and reinforcement, with a focus on maintaining traffic flow for emergency responses. This research provides a new perspective that can aid in prioritizing transportation network resilience measures to reduce the economic and social costs of future extreme weather events.
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  • 73
    Publication Date: 2024-01-29
    Description: The hazardous plasma environment surrounding Earth poses risks to satellites due to internal charging and surface charging effects. Accurate predictions of these risks are crucial for minimizing damage and preparing for system failures of satellites. To forecast the plasma environment, it is essential to know the current state of the system, as the accuracy of the forecast depends on the accuracy of the initial condition of the forecast. In this study, we use data assimilation techniques to combine observational data and model predictions, and present the first global validation of a data-assimilative electron ring current nowcast during a geomagnetic storm. By assimilating measurements from one satellite and validating the results against another satellite in a different magnetic local time sector, we assess the global response and effectiveness of the data assimilation technique for space weather applications. Using this method, we found that the simulation accuracy can be drastically improved at times when observations are available while eliminating almost all of the bias previously present in the model. These findings contribute to the construction of improved operational models in estimating surface charging risks and providing realistic ’source’ populations for radiation belt simulations.
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  • 74
    Publication Date: 2024-01-09
    Description: Analyzing seismic data in a timely manner is essential for potential eruption forecasting and early warning in volcanology. Here, we demonstrate that unsupervised machine learning methods can automatically uncover hidden details from the continuous seismic signals recorded during Iceland’s 2021 Geldingadalir eruption. By pinpointing the eruption’s primary phases, including periods of unrest, ongoing lava extrusion, and varying lava fountaining intensities, we can effectively chart its temporal progress. We detect a volcanic tremor sequence three days before the eruption, which may signify impending eruptive activities. Moreover, the discerned seismicity patterns and their temporal changes offer insights into the shift from vigorous outflows to lava fountaining. Based on the extracted patterns of seismicity and their temporal variations we propose an explanation for this transition. We hypothesize that the emergence of episodic tremors in the seismic data in early May could be related to an increase in the discharge rate in late April.
    Language: English
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  • 75
    Publication Date: 2024-01-09
    Description: In modelling atmospheric loading effects for terrestrial gravimetry, state-of-the-art approaches take advantage of numerical weather models to account for the global 3-D distribution of air masses. Deformation effects are often computed assuming the Inverse Barometer (IB) hypothesis to be generally valid over the oceans. By a revision of the IB assumption and its consequences we show that although the seafloor is not deformed by atmospheric pressure changes, there exists a fraction of ocean mass that current modelling schemes are usually not accounting for. This causes an overestimation of the atmospheric attraction effect over oceans, even when the dynamic response of the ocean to atmospheric pressure and wind is accounted through dynamic ocean models. This signal can reach a root mean square variability of a few nm s−2, depending on the location of the station. We therefore test atmospheric and non-tidal ocean loading effects at five superconducting gravimeter (SG) stations, showing that a better representation of the residual gravity variations is found when Newtonian attraction effects due to the IB response of the ocean are correctly considered. A sliding window variance analysis shows that the main reduction takes place for periods between 5 and 10 d, even for stations far away from the oceans. Since periods of non-tidal ocean mass variability closely resemble atmospheric signals recorded by SGs, we recommend to directly incorporate both an ocean component together with the IB into services that provide weather-related corrections for terrestrial gravimetry.
    Language: English
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  • 76
    Publication Date: 2024-01-09
    Description: More than 20 yr of measurement data of the gravity missions GRACE (Gravity Recovery And Climate Experiment) and GRACE-FO (GRACE-Follow-On) allow detailed investigations of long-term trends in continental terrestrial water storage (TWS). However, the spatial resolution of conventional GRACE/GRACE-FO data products is limited to a few hundred kilometres which restrains from investigating hydrological trends at smaller spatial scales. In this study GRACE and GRACE-FO data have been used to calculate TWS trends with maximized spatial resolution. Conventionally, GRACE/GRACE-FO is presented as a series of either unconstrained gravity fields post-processed with spatial low pass filters or constrained inversions commonly known as Mascon products. This paper demonstrates that both approaches to suppress spatially correlated noise are mathematically equivalent. Moreover, we demonstrate that readily inverting all available sensor data from GRACE/GRACE-FO for a single TWS trend map, together with annual variations and a mean gravity field, provides additional spatial detail not accessible from the standard products. The variable trade-off between spatial and temporal resolution as a unique feature of satellite gravimetry allows for gravity products that are tailored towards specific geophysical applications. We show additional signal content in terms of long-term water storage trends for four dedicated examples (Lake Victoria, Northwest India, Bugachany Reservoir and High Plains Aquifer) for which external information from other remote sensing instruments corroborates the enhanced spatial resolution of the new mean-field trend product.
    Language: English
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  • 77
    Publication Date: 2024-01-09
    Description: Ferropericlase (Mg,Fe)O is after bridgmanite the most abundant phase in the lower mantle. The ultralow velocity zones above the core-mantle boundary may contain very Fe-rich magnesiowüstite (Fe,Mg)O, possibly as result of the fractional crystallisation of a basal magma ocean. We have experimentally studied the solubility of nitrogen in the ferropericlase-magnesiowüstite solid solution series as function of iron content. Multi-anvil experiments were performed at 20–33 GPa and 1600–1800 °C in equilibrium with Fe metal. Nitrogen solubility increases from a few tens ppm (μg/g) for Mg-rich ferropericlase to more than 10 wt. % for nearly pure wüstite. Such high solubilities appear to be due to solid solution with NiAs-type FeN. Our data suggest that during fractional crystallisation of a magma ocean, the core-mantle boundary would have become extremely enriched with nitrogen, such that the deep mantle today could be the largest nitrogen reservoir on Earth. The often discussed “subchondritic N/C” ratio of the bulk silicate Earth may be an artefact of insufficient sampling of this deep reservoir.
    Language: English
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  • 78
    Publication Date: 2024-01-09
    Description: Existing research indicates that to create geothermal reservoirs using CO2 injection, additional stimulation methods are necessary. N, N-bis(carboxymethyl)-L-glutamic acid (GLDA) injection has been predicted to increase the permeability of CO2 injection-induced cloud-fracture networks (CFNs) and could serve as an additional stimulation method. Nevertheless, the influence of differential stress, flow geometry, and scale on the characteristics of permeability enhancement by GLDA injection is yet to be clarified. Accordingly, this study experimentally elucidated the permeability enhancement characteristics of injecting a chelating agent in fractured granite under differential stress conditions as an additional method for creating geothermal reservoirs using CO2 injection. GLDA injection experiments were conducted on fractured-granite samples under conventional- and true-triaxial stress states under varying differential stress and pH conditions. Regardless of the differential stress and pH conditions, rock deformation and acoustic emission (AE) were negligible during the chelating agent flow-through experiments on the fractured samples, whereas similar permeability enhancement factors were achieved within the same duration. Thus, stress did not affect the permeability enhancement by chelating agent injections. The permeability enhancement factors were inferred to be high near the injection borehole because of the high viscosity of the solution. Therefore, reservoir stimulation should be conducted using low-concentration chelating agent solutions at constant injection pressures. The study provides insights into the stimulation strategies for creating geothermal reservoirs using CO2 injection.
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  • 79
    Publication Date: 2024-01-25
    Description: The Varved Sediments Database (VARDA) was launched in 2020 and aimed to establish a community database for annually resolved chronological archives with their associated high-resolution proxy records. This resource would support reproducibility through accessible data for the paleoclimate and modelling communities. In this paper, VARDA has been extended by a dataset of European tephra geochemical data and metadata to enable the synchronisation of varve records during the Last Glacial–Interglacial Transition (LGIT; here defined as 25 to 8 ka; Beckett et al., 2022). Geochemical data from 49 known individual tephra layers across 19 lake records have been included, with Lago di Grande Monticchio being the single biggest contributor of geochemical data with 28 tephra layers. The Vedde Ash and Laacher See tephra are the most common layers found in six different records. This highlights the potential of refining the absolute age estimates for these tephra layers using varve chronologies and for synchronising regional paleoclimate archives. This is the first stage in a 5-year plan funded by the Past Global Changes (PAGES) Data Stewardship Scholarship to incorporate a global dataset of tephra geochemical data into varve records. Further stages of this project will focus on different regions and timescales. Data collated for this project are available open access at https://doi.org/10.5880/fidgeo.2023.015 (Beckett et al., 2022).
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  • 80
    Publication Date: 2024-01-17
    Description: Climate change poses a significant threat to the distribution and composition of forest tree species worldwide. European forest tree species’ range is expected to shift to cope with the increasing frequency and intensity of extreme weather events, pests and diseases caused by climate change. Despite numerous regional studies, a continental scale assessment of current changes in species distributions in Europe is missing due to the difficult task of modeling a species realized distribution and to quantify the influence of forest disturbances on each species. In this study we conducted a trend analysis on the realized distribution of 6 main European forest tree species (Abies alba Mill., Fagus sylvatica L., Picea abies L. H. Karst., Pinus nigra J. F. Arnold, Pinus sylvestris L. and Quercus robur L.) to capture and map the prevalent trends in probability of occurrence for the period 2000–2020. We also analyzed the impact of forest disturbances on each species’ range and identified the dominant disturbance drivers. Our results revealed an overall trend of stability in species’ distributions (85% of the pixels are considered stable by 2020 for all species) but we also identified some hot spots characterized by negative trends in probability of occurrence, mostly at the edges of each species’ latitudinal range. Additionally, we identified a steady increase in disturbance events in each species’ range by disturbance (affected range doubled by 2020, from 3.5% to 7% on average) and highlighted species-specific responses to forest disturbance drivers such as wind and fire. Overall, our study provides insights into distribution trends and disturbance patterns for the main European forest tree species. The identification of range shifts and the intensifying impacts of disturbances call for proactive conservation efforts and long-term planning to ensure the resilience and sustainability of European forests.
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  • 81
    Publication Date: 2024-01-22
    Description: The European Geosciences Union (EGU) brings together geoscientists from all over Europe and the rest of the world, covering all disciplines of Earth, planetary and space sciences. The Division on Energy, Resources and the Environment (ERE), as part of the EGU, follows an interdisciplinary approach to serve society and provide solutions to challenges of our time and in the future. One task for humankind, for example, is to provide adequate and reliable supplies of affordable energy and other resources, obtained in environmentally sustainable ways, which will be essential for economic prosperity, environmental quality and political stability around the world. This volume of Advances in Geosciences spans the range of topics of the division and continues a series of ten ERE special issues over the course of the last ten years. We incorporate emerging topics into the division ERE along the line and we advocate that every idea and opportunity should be studied and tested.
    Description: The European Geosciences Union (EGU) brings together geoscientists from all over Europe and the rest of the world, covering all disciplines of Earth, planetary and space sciences. The Division on Energy, Resources and the Environment (ERE), as part of the EGU, follows an interdisciplinary approach to serve society and provide solutions to challenges of our time and in the future. One task for humankind, for example, is to provide adequate and reliable supplies of affordable energy and other resources, obtained in environmentally sustainable ways, which will be essential for economic prosperity, environmental quality and political stability around the world. This volume of Advances in Geosciences spans the range of topics of the division and continues a series of ten ERE special issues over the course of the last ten years. We incorporate emerging topics into the division ERE along the line and we advocate that every idea and opportunity should be studied and tested.
    Language: English
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  • 82
    Publication Date: 2024-01-31
    Description: The ‘Fermi paradox’ refers to the mismatch between a widely held expectation that advanced technological life should be common in the Universe—recently given impetus by the discovery that other planetary systems are common—and the absence of any evidence for it. Here we briefly review attempted solutions to the paradox and conclude that either (1) extraterrestrial technological civilizations are extremely rare (or absent) in the Galaxy or (2) they exist but are deliberately hiding from us, a scenario generally known as the ‘zoo hypothesis’. In this sense, we propose that the answer to the Fermi paradox is ‘the zoo hypothesis or nothing’. We argue that, given a strong commitment to the continued exploration of the Universe, humanity may be able to distinguish between these two alternatives within the next half-century.
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  • 83
    Publication Date: 2024-01-23
    Description: For an ω2-source model, moment-based estimates of the stress drop are obtained by combining corner frequency and seismic moment source parameters. Therefore, the moment-based estimates of the stress drop are informative about the amount of energy radiated at high frequencies by dynamic rupture processes. This study aims to systematically estimate such stress drop from the harmonized dataset at the European scale and to characterize the distributions of the stress drop for application in future stochastic simulations. We analyze the seismological records associated with shallow crustal seismic events that occurred in Western Europe between January 1990 and May 2020. We processed 220,000 high-quality records and isolated the contributions of the source, site, and path contributions using the Generalized Inversion Technique. The source parameters, including the corner frequency, moment magnitude, and stress drop, of 6135 seismic events are calculated. The events processed are mainly tectonic events (e.g., earthquakes of the central Italy 2009–2016 sequence), although non-tectonic events associated with the Groningen gas field and mining activities in Western Europe are also included in the analysis. The impact of different attenuation models and reference site choices are evaluated. Most of the obtained source spectra follow the standard ω2-model except for a few events where the data sampling considered does not allow an effective spectral decomposition. The resulting stress drop shows a positive correlation with moment magnitude between 3 and 4, and a self-similarity for magnitudes greater than 4 with a mean stress drop of 13.8 MPa.
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  • 84
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    In:  Advances in Natural Gas: Formation, Processing, and Applications. Volume 3: Natural Gas Hydrates
    Publication Date: 2024-02-23
    Language: English
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  • 85
  • 86
    Publication Date: 2024-02-23
    Description: Several studies investigated changes in microbial community composition in thawing permafrost landscapes, but microbial assemblages in the transient ecosystems of the Arctic coastline remain poorly understood. Thermokarst lakes, abrupt permafrost thaw features, are widespread along the pan-Arctic coast and transform into thermokarst lagoons upon coastal erosion and sea-level rise. This study looks at the effect of marine water inundation (imposing a sulfate-rich, saline environment on top of former thermokarst lake sediments) on microbial community composition and the processes potentially driving microbial community assembly. In the uppermost lagoon sediment influenced from marine water inflow, the microbial structures were significantly different from those deeper in the lagoon sediment and from those of the lakes. In addition, they became more similar along depth compared with lake communities. At the same time, the diversity of core microbial consortia community decreased compared with the lake sediments. This work provides initial observational evidence that Arctic thermokarst lake to lagoon transitions do not only substantially alter microbial communities but also that this transition has a larger effect than permafrost thaw and lake formation history.
    Language: English
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  • 87
    Publication Date: 2024-02-23
    Description: Many observed time series of precipitation and streamflow show heavy-tail behaviour. For heavy-tailed distributions, the occurrence of extreme events has a higher probability than for distributions with an exponentially receding tail. If we neglect heavy-tail behaviour we might underestimate the magnitude of rarely observed, high-impact events. Robust estimation of upper-tail behaviour is often hindered by the limited length of observational records. Using long time series and a better understanding of the relevant process controls can help with achieving more robust tail estimations. Here, a simulation-based approach is used to analyse the effect of precipitation and runoff generation characteristics on the upper tail of flood peak distributions. Long, synthetic precipitation time series with different tail behaviour are produced by a stochastic weather generator. These are used to force a conceptual rainfall–runoff model. In addition, catchment characteristics linked to a threshold process in the runoff generation are varied between model runs. We characterize the upper-tail behaviour of the simulated precipitation and discharge time series with the shape parameter of the generalized extreme value (GEV) distribution. Our analysis shows that runoff generation can strongly modulate the tail behaviour of flood peak distributions. In particular, threshold processes in the runoff generation lead to heavier tails. Beyond a certain return period, the influence of catchment processes decreases and the tail of the rainfall distribution asymptotically governs the tail of the flood peak distribution. Beyond which return period this is the case depends on the catchment storage in relation to the mean annual rainfall amount.
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  • 88
    Publication Date: 2024-02-12
    Description: For robust multi-modal person re-identification (re-ID) models, it is crucial to effectively utilize the complementary information and constraint relationships among different modalities. However, current multi-modal methods often overlook the correlation between modalities at the feature fusion stage. To address this issue, we propose a novel multimodal person re-ID method called Transformer Relation Regularization (TRR). Firstly, we introduce an adaptive collaborative matching module that facilitates the exchange of useful information by mining feature correspondences between modalities. This module allows for the integration of complementary information, enhancing the re-ID performance. Secondly, we propose an enhanced embedded module that corrects general information using discriminative information within each modality. By leveraging this approach, we improve the model’s stability in challenging multi-modal environments. Lastly, we propose an adaptive triple loss to enhance sample utilization efficiency and mitigate the problem of inconsistent representation among multimodal samples. This loss function optimizes the model’s ability to distinguish between different individuals, leading to improved re-ID accuracy. Experimental results on several challenging visible-infrared person re-ID benchmark datasets demonstrate that our proposed TRR method achieves optimal performance. Additionally, extensive ablation studies validate the effective contribution of each component to the overall model. In summary, our proposed TRR method effectively leverages complementary information, addresses the correlation between modalities, and improves the re-ID performance in multi-modal scenarios. The results obtained from various benchmark datasets and the comprehensive analysis support the efficacy of our approach.
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  • 89
    Publication Date: 2024-02-12
    Description: Tree-specific canopy conductance (Gc) and its adjustment play a critical role in mitigating excess water loss in changing environmental conditions. However, the change of Gc sensitivity to environmental conditions due to drought remains unclear for European tree species. Here we quantified the environmental operational space of Gc, i.e., the water supply (soil moisture, tree water deficit) and demand conditions (vapor pressure deficit) under which Gc ≥ 50% is possible (Gc50OS), at two sites with different soil water availability for three common European tree species. We collected sap flow and dendrometer measurements for co-occurring Pinus sylvestris, Fagus sylvatica and Quercus petraea growing under different soil hydrological conditions (drier/wetter). These measurements were combined with meteorological variables and soil moisture conditions in five depths. Dendrometer measurements were used to confirm soil water availability patterns. For all analyses, the contrasting soil hydrology between sites was the main driver of Gc response. At the drier sites, F. sylvatica and P. sylvestris reduced their water consumption in response to decreasing soil water supply earlier in the growing season than Q. petraea. However, our analysis on the Gc50OS revealed that at the drier sites, F. sylvatica and Q. petraea reduced the extent of their Gc50OS to a higher degree than P. sylvestris. This indicates a higher level of Gc50OS adjustment to the drier site conditions for the two broadleaved species. These differences were more pronounced when using the dendrometer-derived tree internal water status as proxy for tree water supply. Our results provide preliminary evidence for diverging short-term Gc responses when temperate trees are exposed to prolonged reduction in water availability. These findings suggest that Gc50OS can help to constrain species-specific predictions of water use by mature trees, especially when combined with high-resolution water potential measurements.
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  • 90
    Publication Date: 2024-02-12
    Description: The International GNSS Service (IGS) provides combined satellite and station clock products, which are generated from the individual clock solutions produced by the analysis centers (ACs). Combinations for GPS and GLONASS are currently available, but there is still a lack of combined products for the new constellations such as Galileo, BeiDou, and QZSS. This study presents a combination framework based on least squares variance component estimation using the ACs’ aligned clock solutions. We present the various alignments required to harmonize the solutions from the ACs, namely the radial correction derived from the differences of the associated orbits, the alignment of the AC clocks to compensate for different reference clocks within each AC solution, and the inter-system bias (ISB) alignment to correct for different AC ISB definitions when multiple constellations are used. The combination scheme is tested with IGS MGEX and repro3 products. The RMS computed between the combined product and the aligned ACs’ solutions differ for each constellation, where the lowest values are obtained for Galileo and GPS with on average below 45 psec (13 mm) and reaching more than 150 psec (45 mm) for QZSS. The same behavior is repeated when the process is performed with the repro3 products. A clock and orbit combination validation is done using precise point positioning (PPP) that shows ionosphere-free phase residuals below 10 mm for all constellations, comparable with the AC solutions that are in the same level.
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  • 91
    Publication Date: 2024-02-15
    Description: We provide grid files that collectively allow recreating 3D structural subsurface model of Brandenburg discussed in the papers (Noack, et al., 2010), (Noack, et al., 2012) and (Noack, 2013). The crustal-scale model covers an area of 250 km in E–W direction and 210 km in N–S direction and is located in the Northeast German Basin (NEGB). We provide ASCII files with top surface elevation and thickness of individual stratigraphic layers. There are two versions of the stratigraphic layering: one with the Rupelian clay layer and one without it. The coordinate system used is Gauss Krueger zone 4.
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  • 92
    Publication Date: 2024-02-15
    Description: Investigating past interglacial climatic and environmental changes can enhance our understanding of the natural rates and ranges of climate variability under interglacial boundary conditions. However, comparing past interglacial palaeoclimate records from different regions and archives is often complicated by differing and uncertain chronologies. For instance, the duration of the Last Interglacial in Europe is still controversial as southern European palaeoclimate records suggest a duration of ~16 500–18 000 years, while a length of only ~11 000 years in northern-central Europe was previously inferred from the analysis of partly annually laminated (varved) palaeolake sediments recovered at Bispingen, northern Germany. To resolve this discrepancy, we here present sediment microfacies, geochemistry and pollen data from a new sediment core from the Bispingen palaeolake sediment succession, covering the entire Last Interglacial (Eemian) and the earliest part of the Last Glacial (Weichselian). In particular, we provide evidence that the duration of the Last Interglacial at Bispingen must have been hitherto underestimated due to the investigation of an incomplete sediment core. Using microscopic varve counting and sedimentation rate estimates for non-varved sections on the new sediment core, we show that the Eemian in northern-central Europe probably lasted at least ~15 000 years, about 4000 years longer than previously thought. This new duration estimate is in much better agreement with results from southern European palaeoclimate records, clarifying the enigma of a steep trans-European vegetation gradient for several millennia at the end of the Last Interglacial.
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  • 93
    Publication Date: 2024-02-15
    Description: The dry continental interior of Asia has remained arid throughout most of its geological history, yet the future of this unique ecosystem remains unclear. Here we use palynological and isotopic records to track vegetation and moisture throughout the warm early Eocene (57 to 44 million years ago) as an analogue for extreme atmospheric CO2 scenarios. We show that rainfall temporarily doubled and replaced the regional steppe by forested ecosystems. By reconstructing the season of pedogenic carbonate growth, we constrain the soil hydrologic regime and show that most of this rainfall occurred during the summer season. This humid event is therefore attributed to an inland expansion of monsoonal moisture following the massive greenhouse gas release of the Palaeocene–Eocene Thermal Maximum as identified by a negative carbon isotope excursion. The resulting abrupt greening of the Central Asian steppe-desert would have enabled mammal dispersal and could have played a role in carbon cycle feedbacks by enhancing soil organic carbon burial and silicate weathering. These extreme Eocene proto-monsoons, albeit different from the topography-driven Asian monsoon today, highlight the potential for abrupt shifts in Central Asian rainfall and ecosystems under future global warming.
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  • 94
    Publication Date: 2024-02-15
    Description: High-resolution flood maps are needed for more effective flood risk assessment and management. Producing these directly with hydrodynamic models is slow and computationally prohibitive at large scales. Here we demonstrate a new algorithm for post-processing low-resolution inundation layers by using high-resolution terrain models to disaggregate or downscale. The new algorithm is roughly 8 times faster than state-of-the-art algorithms and shows a slight improvement in accuracy when evaluated against observations of a recent flood using standard performance metrics. Qualitatively, the algorithm generates more physically coherent flood maps in some hydraulically challenging regions compared to the state of the art. The algorithm developed here is open source and can be applied in conjunction with a low-resolution hydrodynamic model and a high-resolution DEM to rapidly produce high-resolution inundation maps. For example, in our case study with a river reach of 20 km, the proposed algorithm generated a 4 m resolution inundation map from 32 m hydrodynamic model outputs in 33 s compared to a 4 m hydrodynamic model runtime of 34 min. This 60-fold improvement in runtime is associated with a 25 % increase in RMSE when compared against the 4 m hydrodynamic model results and observations of a recent flood. Substituting downscaling into flood risk model chains for high-resolution modelling has the potential to drastically improve the efficiency of inundation map production and increase the lead time of impact-based forecasts, helping more at-risk communities prepare for and mitigate flood damages.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 95
    Publication Date: 2024-02-15
    Description: To design user-centred and scientifically high-quality outreach products to inform about earthquake-related hazards and the associated risk, a close collaboration between the model developers and communication experts is needed. In this contribution, we present the communication strategy developed to support the public release of the first openly available European Seismic Risk Model and the updated European Seismic Hazard Model. The backbone of the strategy was the communication concept in which the overall vision, communication principles, target audiences (including personas), key messages, and products were defined. To fulfil the end-users' needs, we conducted two user testing surveys: one for the interactive risk map viewer and one for the risk poster with a special emphasis on the European earthquake risk map. To further ensure that the outreach products are not only understandable and attractive for different target groups but also adequate from a scientific point of view, a two-fold feedback mechanism involving experts in the field was implemented. Through a close collaboration with a network of communication specialists from other institutions supporting the release, additional feedback and exchange of knowledge was enabled. Our insights, gained as part of the release process, can support others in developing user-centred products reviewed by experts in the field to inform about hazard and risk models.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 96
    Publication Date: 2024-02-13
    Description: Volcanism in continental rifts is generally observed to shift over time from the inside of the basin to its flanks and vice versa, but the controls on these switches are still unclear. Here we use numerical simulations of dike propagation to test the hypothesis that the spatio-temporal evolution of rift volcanism is controlled by the crustal stresses produced during the development of the rift basin. We find that the progressive deepening of a rift rotates the direction of the principal stresses under the basin, deflecting ascending dikes. This causes an early shift of volcanism from the inside of the graben to its flanks. The intensification of this stress pattern, due to further deepening of the basin, promotes the formation of lower crustal sill-like intrusions that can stack under the rift, shallowing the depth at which dikes nucleate, eventually causing a late stage of in-rift axial volcanism. Given the agreement between our model results and observations, we conclude that the temporal shifts in the location of rift volcanism are controlled to first order by the elastic stresses developing in the crust as the rift matures. We thereby suggest that geodynamic models should account for elasticity and the redistribution of surface loads in order to effectively reproduce rift-related magmatism.
    Type: info:eu-repo/semantics/article
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  • 97
    facet.materialart.
    Unknown
    Universität Potsdam
    Publication Date: 2024-02-13
    Description: Large parts of the Earth’s interior are inaccessible to direct observation, yet global geodynamic processes are governed by the physical material properties under extreme pressure and temperature conditions. It is therefore essential to investigate the deep Earth’s physical properties through in-situ laboratory experiments. With this goal in mind, the optical properties of mantle minerals at high pressure offer a unique way to determine a variety of physical properties, in a straight-forward, reproducible, and time-effective manner, thus providing valuable insights into the physical processes of the deep Earth. This thesis focusses on the system Mg-Fe-O, specifically on the optical properties of periclase (MgO) and its iron-bearing variant ferropericlase ((Mg,Fe)O), forming a major planetary building block. The primary objective is to establish links between physical material properties and optical properties. In particular the spin transition in ferropericlase, the second-most abundant phase of the lower mantle, is known to change the physical material properties. Although the spin transition region likely extends down to the core-mantle boundary, the ef-fects of the mixed-spin state, where both high- and low-spin state are present, remains poorly constrained. In the studies presented herein, we show how optical properties are linked to physical properties such as electrical conductivity, radiative thermal conductivity and viscosity. We also show how the optical properties reveal changes in the chemical bonding. Furthermore, we unveil how the chemical bonding, the optical and other physical properties are affected by the iron spin transition. We find opposing trends in the pres-sure dependence of the refractive index of MgO and (Mg,Fe)O. From 1 atm to ~140 GPa, the refractive index of MgO decreases by ~2.4% from 1.737 to 1.696 (±0.017). In contrast, the refractive index of (Mg0.87Fe0.13)O (Fp13) and (Mg0.76Fe0.24)O (Fp24) ferropericlase increases with pressure, likely because Fe Fe interactions between adjacent iron sites hinder a strong decrease of polarizability, as it is observed with increasing density in the case of pure MgO. An analysis of the index dispersion in MgO (decreasing by ~23% from 1 atm to ~103 GPa) reflects a widening of the band gap from ~7.4 eV at 1 atm to ~8.5 (±0.6) eV at ~103 GPa. The index dispersion (between 550 and 870 nm) of Fp13 reveals a decrease by a factor of ~3 over the spin transition range (~44–100 GPa). We show that the electrical band gap of ferropericlase significantly widens up to ~4.7 eV in the mixed spin region, equivalent to an increase by a factor of ~1.7. We propose that this is due to a lower electron mobility between adjacent Fe2+ sites of opposite spin, explaining the previously observed low electrical conductivity in the mixed spin region. From the study of absorbance spectra in Fp13, we show an increasing covalency of the Fe-O bond with pressure for high-spin ferropericlase, whereas in the low-spin state a trend to a more ionic nature of the Fe-O bond is observed, indicating a bond weakening effect of the spin transition. We found that the spin transition is ultimately caused by both an increase of the ligand field-splitting energy and a decreasing spin-pairing energy of high-spin Fe2+.
    Description: Geodynamische Prozesse werden von den physikalischen Materialeigenschaften unter den extremen Druck- und Temperaturbedingungen des Erdinneren gesteuert, gerade diese Areale sind aber faktisch nicht für direkte Beobachtungen zugänglich. Umso wichtiger ist es, die physikalischen Eigenschaften unter Bedingungen des Erdinneren zu untersuchen. Mit diesem Ziel vor Augen erlaubt das Studium der optischen Eigenschaften von Mineralen des Erdmantels, eine große Bandbreite an physikalischen Materialeigenschaften, in einer einfachen, reproduzierbaren und effizienten Art und Weise zu bestimmen. Dadurch bieten sich wichtige Einblicke in die physikalischen Prozessen des Erdinneren. Die vorliegende Arbeit konzentriert sich auf das System Mg-Fe-O, im Speziellen auf Periklas (MgO) und seine Eisen-haltige Variante Ferroperiklas ((Mg,Fe)O), ein wichtiger Baustein planetarer Körper. Das Hauptziel der Arbeit besteht darin Verbindungen zwischen optischen Eigenschaften und physikalischen Materialeigenschaften zu finden. Gerade der Spin-Übergang in Ferroperiklas, der zweithäufigsten Phase des unteren Erdmantels, ist dabei von Bedeutung, da damit Veränderungen in den physikalischen Materialeigenschaften einhergehen. Obwohl sich der Spinübergangsbereich vermutlich bis zur Kern-Mantel-Grenze erstreckt, sind die Auswirkungen des gemischten Spin-Zustandes, bei dem sowohl Hoch- als auch Tief-Spin präsent sind, nur unzureichend untersucht. Die hier vorgestellten Studien zeigen, wie optische Eigenschaften mit anderen wichtigen physikalischen Eigenschaften wie elektrischer und thermischer Leitfähigkeit, Viskosität oder auch mit der chemischen Bindung verbunden sind. Daraus lässt sich auch ableiten wie der Spin-Übergang in Ferroperiklas diese Eigenschaften beeinflusst. Von Raumbedingungen bis zu ~140 GPa sinkt der Brechungsindex von MgO um ~2.4 % von 1.737 auf 1.696 (±0.017). Im Gegensatz dazu steigt der Brechungsindex von (Mg0.87Fe0.13)O (Fp13) und (Mg0.76Fe0.24)O (Fp24) Ferroperiklas mit dem Druck an. Dies ist auf Fe-Fe Wechselwirkungen zwischen benachbarten Eisenpositionen zurückzuführen, die eine starke Verringerung der Polarisierbarkeit, wie im Falle von reinem MgO mit zunehmender Dichte, behindern. Eine Analyse der Dispersion des Brechungsindexes von MgO (Abnahme um ~23 % von 1 Atm zu ~103 GPa) offenbart eine Verbreiterung der Bandlücke von ~7.4 eV bei 1 Atm zu ~8.5 (±0.6) eV bei ~103 GPa. Die Messung der Dispersion (zwischen 550 und 870 nm) in Fp13 zeigt eine starke Abnahme über den Bereich des Spin-Überganges (~44–100 GPa) bis zu einem Faktor von ~3. Die Bandlücke nimmt in der Region des gemischten Spin-Zustandes signifikant auf bis zu ~4.7 eV zu (entspricht einer Zunahme um den Faktor ~1.7). Dies deutet auf eine Verringerung der Elektronen-Mobilität zwischen benachbarten Fe2+-Positionen mit unterschiedlichem Spin-Zustand hin, was die bereits in früheren Arbeiten beobachtete Abnahme der elektrischen Leitfähigkeit im Bereich des gemischten Spin-Zustandes erklärt. Absorptionsspektren an Fp13 zeigen eine Druck-bedingte Zunahme der Kovalenz der Fe-O Bindung für Ferroperiklas im Hoch-Spin Zustand, wohingegen Tief-Spin Ferroperiklas einen Trend zu einer mehr ionischen Fe-O Bindung auf-weist, was auf einen Bindungs-schwächenden Effekt des Spin-Wechsels hinweist. Der Übergang von Hoch- zu Tiefspin ist letztlich auf eine Zunahme der Ligandenfeldaufspaltungsenergie sowie eine abnehmende Spinpaarungsenergie von Hoch-Spin Fe2+ zurückzuführen.
    Language: English
    Type: info:eu-repo/semantics/doctoralThesis
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  • 98
    facet.materialart.
    Unknown
    Publication Date: 2024-02-13
    Language: English
    Type: info:eu-repo/semantics/lecture
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  • 99
    Publication Date: 2024-02-13
    Description: Sequential climate hazards, such as “warm and wet” compound extremes, have direct societal implications for highly urbanized regions and agricultural production. While typically extreme temperatures and rainfall are inversely correlated during the summer, extreme humid heatwaves often lead to atmospheric instability and moisture convection, increasing the likelihood of extreme precipitation (EP). Little is known about how heatwave characteristics, such as peak intensity and duration, influence EP at a regional scale. Using high-resolution, sub-daily station-based observational records over five decades (1971–2021) across India, we find a robust increase in the frequency of compound humid heat-peak precipitation events in all seasons. Our sensitivity analysis of the impact of humid heatwave characteristics on the subsequent sub-daily rainfall extremes reveals that, with an increase in peak heatwave intensity for a given heatwave duration, 〉50% of sites show an increase in the magnitude of rainfall; conversely, with an increase in heatwave duration for a given peak heatwave intensity, around 67% sites show a decline in sub-daily rainfall extremes. An asymmetrical shift toward above-average precipitation extremes in response to humid heat stress is mainly clustered around low-elevation, densely populated coastal areas and the irrigation-intensive Indo-Gangetic Plains.
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  • 100
    Publication Date: 2024-02-16
    Description: The bacterial strains Brochothrix thermosphacta DH-B18 and Rathayibacter sp. DH-RSZ4 were isolated from raw sausage and escalope samples and grown in a CO2-rich modified atmosphere. Here, we present both circular genomes obtained by nanopore sequencing.
    Language: English
    Type: info:eu-repo/semantics/article
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