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  • 1
    facet.materialart.
    Unbekannt
    Wien : [Verlag nicht ermittelbar] ; 22.1910/25(1925),3; 23.1914/31(1929/31),2-3; 24.1927,1-2; 25.1939,1; 26.1948,1; 27.1971-Band 76 (2022)
    Signatur: S 91.1179
    ISSN: 0375-5797 , 0378-0864
    Paralleltitel: 35=2 von European Conodont Symposium (ZDB) Guidebook, abstracts / European Conodont Symposium
    Paralleltitel: 41=2 von Workshop on Agglutinated Foraminifera (ZDB) Proceedings / Workshop on Agglutinated Foraminifera. Geologische Bundesanstalt
    Paralleltitel: 39=3 von International Nannoplankton Association Proceedings of the ... International Nannoplankton Association conference
    Paralleltitel: 60=11 von Deutsche Gesellschaft für Geowissenschaften. Fachsektion GeoTop Internationale Jahrestagung der Fachsektion GeoTop der Deutschen Gesellschaft für Geowissenschaften
    Vorheriger Titel: Vorg. Geologische Reichsanstalt Abhandlungen der Kaiserlich-Königlichen Geologischen Reichsanstalt, Wien
    Nachfolgender Titel: Fortgesetzt durch Abhandlungen
    Sprache: Deutsch
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Monographie ausleihbar
    Monographie ausleihbar
    Stuttgart : Schweizerbart Science Publishers ; Volume 1, number 1 (1978)-
    Signatur: M 18.91571
    Materialart: Monographie ausleihbar
    Seiten: 134 Seiten
    ISSN: 2363-7196
    Serie: Global tectonics and metallogeny : special issue Vol. 10/2-4
    Klassifikation:
    Tektonik
    Paralleltitel: Erscheint auch als Global tectonics and metallogeny
    Sprache: Englisch
    Standort: Kompaktmagazin oben
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Signatur: AWI A3-20-93434
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 1
    Materialart: Schriftenreihen ausleihbar
    Seiten: 121 Seiten , Illustrationen
    Serie: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,1
    Sprache: Deutsch
    Anmerkung: 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
    Standort: AWI Lesesaal
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Zeitschrift ausleihbar
    Zeitschrift ausleihbar
    Tübingen : Mohr Siebeck ; 1.1884 - 48.1931; N.F. 1.1932/33 - 10.1943/44(1945),3; 11.1948/49(1949) -
    Signatur: ZS 22.95039
    Materialart: Zeitschrift ausleihbar
    Seiten: Online-Ressource
    ISSN: 1614-0974 , 0015-2218 , 0015-2218
    Sprache: Deutsch , Englisch
    Anmerkung: N.F. entfällt ab 57.2000. - Volltext auch als Teil einer Datenbank verfügbar , Ersch. ab 2000 in engl. Sprache mit dt. Hauptsacht.
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Signatur: AWI A3-20-93434-2
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 2
    Materialart: Schriftenreihen ausleihbar
    Seiten: 218 Seiten , Illustrationen
    Serie: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,2
    Sprache: Deutsch
    Anmerkung: 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
    Standort: AWI Lesesaal
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Signatur: IASS 15.89494
    Materialart: Monographie ausleihbar
    Seiten: Losebl.-Ausg.
    Ausgabe: Stand: Oktober 2010
    ISBN: 9783768501828
    Sprache: Deutsch
    Zweigbibliothek: RIFS Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Monographie ausleihbar
    Monographie ausleihbar
    Garmisch-Partenkirchen : Institut für atmosphärische Umweltforschung der Fraunhofer- Gesellschaft
    Signatur: MOP 44829 / Mitte
    Materialart: Monographie ausleihbar
    Seiten: 25 S. , graph. Darst.
    Sprache: Englisch
    Standort: MOP - Bitte bestellen
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Monographie ausleihbar
    Monographie ausleihbar
    [Edgecumbe, N.Z.] : A. Muller
    Signatur: M 15.89146
    Beschreibung / Inhaltsverzeichnis: 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
    Materialart: Monographie ausleihbar
    Seiten: 223 S., , Ill.
    Sprache: Englisch
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Monographie ausleihbar
    Monographie ausleihbar
    Madrid : Secc
    Signatur: PIK N 456-17-90913
    Materialart: Monographie ausleihbar
    Seiten: 536 Seiten
    Serie: Ministerio de Transportes Turismo Y Comunicaciones : Publicación Serie A 114
    Paralleltitel: 1,1=6; 2,1=13 von Publicaciones / D / Ministerio del Aire, Subsecretaria de Aviación Civil, Servicio Meteorológico Nacional
    Sprache: Spanisch
    Standort: A 18 - Bitte bestellen
    Zweigbibliothek: PIK Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Signatur: (DE-599)GBV03709842X
    Materialart: Monographie ausleihbar
    Sprache: Deutsch
    Standort: MOP - Bitte bestellen
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Monographie ausleihbar
    Monographie ausleihbar
    Leningrad : Gidrometeorolog. Izd.
    Signatur: MOP 33767
    Materialart: Monographie ausleihbar
    Seiten: 663 S.
    Sprache: Russisch
    Anmerkung: In kyrill. Schr., russ.
    Standort: MOP - Bitte bestellen
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Signatur: MOP 19538/1d-6d
    Materialart: Monographie ausleihbar
    Seiten: 111 S.
    ISSN: 0486-2287
    Sprache: Russisch
    Anmerkung: In kyrill. Schr.
    Standort: MOP - Bitte bestellen
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    facet.materialart.
    Unbekannt
    IEEE
    In:  EPIC3IEEE Transactions on Geoscience and Remote Sensing, IEEE, (60), pp. 1-16, ISSN: 0196-2892
    Publikationsdatum: 2022-04-08
    Beschreibung: We present new high-resolution snow depth data on Arctic sea ice derived from airborne microwave radar measurements from the IceBird campaigns of the Alfred Wegener Institute (AWI) together with a new retrieval method using signal peakiness based on an intercomparison exercise of colocated data at different altitudes. We aim to demonstrate the capabilities and potential improvements of radar data, which were acquired at a lower altitude (200 ft) and slower speed (110 kn) and had a smaller radar footprint size (2-m diameter) than previous airborne snow radar data. So far, AWI Snow Radar data have been derived using a 2-18-GHz ultrawideband frequency-modulated continuous-wave (FMCW) radar in 2017-2019. Our results show that our method in combination with thorough calibration through coherent noise removal and system response deconvolution significantly improves the quality of the radar-derived snow depth data. The validation against a 2-D grid of in situ snow depth measurements on level landfast first-year ice indicates a mean bias of only 0.86 cm between radar and ground truth. Comparison between the radar-derived snow depth estimates from different altitudes shows good consistency. We conclude that the AWI Snow Radar aboard the IceBird campaigns is able to measure the snow depth on Arctic sea ice accurately at higher spatial resolution than but consistent with the existing airborne snow radar data of NASA Operation IceBridge. Together with the simultaneous measurements of the total ice thickness and surface freeboard, the IceBird campaign data will be able to describe the whole sea-ice column on regional scales.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Publikationsdatum: 2022-04-12
    Beschreibung: The West Antarctic Ice Sheet (WAIS) is one of the largest potential sources of future sea-level rise, with glaciers draining the WAIS thinning at an accelerating rate over the past 40 years. Due to complexities in calibrating palaeoceanographic proxies for the Southern Ocean, it remains difficult to assess whether similar changes have occurred earlier during the Holocene or whether there is underlying centennial- to millennial-scale forcing in oceanic variability. Archaeal lipid-based proxies, specifically glycerol dialkyl glycerol tetraether (GDGT; e.g. TEX86 and TEXL86), are powerful tools for reconstructing ocean temperature, but these proxies have been shown previously to be difficult to apply to the Southern Ocean. A greater understanding of the parameters that control Southern Ocean GDGT distributions would improve the application of these biomarker proxies and thus help provide a longer-term perspective on ocean forcing of Antarctic ice sheet changes. In this study, we characterised intact polar lipid (IPL)-GDGTs, representing (recently) living archaeal populations in suspended particulate matter (SPM) from the Amundsen Sea and the Scotia Sea. SPM samples from the Amundsen Sea were collected from up to four water column depths representing the surface waters through to Circumpolar Deep Water (CDW), whereas the Scotia Sea samples were collected along a transect encompassing the sub-Antarctic front through to the southern boundary of the Antarctic Circumpolar Current. IPL-GDGTs with low cyclic diversity were detected throughout the water column with high relative abundances of hydroxylated IPL-GDGTs identified in both the Amundsen and Scotia seas. Results from the Scotia Sea show shifts in IPL-GDGT signatures across well-defined fronts of the Southern Ocean. Indicating that the physicochemical parameters of these water masses determine changes in IPL-GDGT distributions. The Amundsen Sea results identified GDGTs with hexose-phosphohexose head groups in the CDW, suggesting active GDGT synthesis at these depths. These results suggest that GDGTs synthesised at CDW depths may be a significant source of GDGTs exported to the sedimentary record and that temperature reconstructions based on TEX86 or TEXL86 proxies may be significantly influenced by the warmer waters of the CDW.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev , info:eu-repo/semantics/article
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Publikationsdatum: 2022-04-12
    Beschreibung: In this paper we analyze how oceanic circulation affects sediment deposition along a sector of the Ross Sea continental margin, between the Iselin Bank and the Hillary Canyon, and how these processes evolved since the Late Miocene. The Hillary Canyon is one of the few places around the Antarctic continental margin where the dense waters produced onto the continental shelf, mainly through brine rejection related to sea ice production, flow down the continental slope and reach the deep oceanic bottom layer. At the same time the Hillary Canyon represents a pathway for relatively warm waters, normally flowing along the continental slope within the Antarctic Slope Current, to reach the continental shelf. The intrusion of warm waters onto the continental shelf produces basal melting of the ice shelves, reduces their buttressing effect and triggers instabilities of the ice sheet that represent one of the main uncertainties in future sea level projections. For this study we use seismic, morpho-bathymetric and oceanographic data acquired in 2017 by the R/V OGS Explora. Seismic profiles and multibeam bathymetry are interpreted together with age models from two drilling sites (U1523 and U1524) of the International Ocean Discovery Program (IODP) Expedition 374. Oceanographic data, together with a regional oceanographic model, are used to support our reconstruction by showing the present-day oceanographic influence on sediment deposition. Regional correlation of the main seismic unconformities allows us to identify eight seismic sequences. Seismic profiles and multibeam bathymetry show a strong influence of bottom current activity on sediment deposition since the Early Miocene and a reduction in their intensity during the mid-Pliocene Warm Period. Oceanographic data and modelling provide evidence that the bottom currents are related to the dense waters produced on the Ross Sea continental shelf and flowing out through the Hillary Canyon. The presence of extensive mass transport deposits and detachment scarps indicate that also mass wasting participates in sediment transport. Through this integrated approach we regard the area between the Iselin Bank and the Hillary Canyon as a Contourite Depositional System (ODYSSEA CDS) that offers a record of oceanographic and sedimentary conditions in a unique setting. The hypotheses presented in this work are intended to serve as a framework for future reconstructions based on detailed integration of lithological, paleontological, geochemical and petrophysical data.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev , info:eu-repo/semantics/article
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Publikationsdatum: 2022-04-04
    Beschreibung: Harmful algal blooms (HABs) are globally increasing in number and spatial extent. However, their propagation dynamics along environmental gradients and the associated interplay of abiotic factors and biotic interactions are still poorly understood. In this study, a nutrient gradient was established in a linear meta‐ecosystem setup of five interconnected flasks containing an artificially assembled phytoplankton community. The harmful dinoflagellate Alexandrium catenella was introduced into different positions along the nutrient gradient to investigate dispersal and spatial community dynamics. Overall, total algal biovolume increased, while community evenness decreased with increasing nutrient concentrations along the gradient. Alexandrium was able to disperse through all flasks. On the regional scale, diatoms dominated the community, whereas on the local scale the dinoflagellate showed higher contributions at low nutrient concentrations and dominated the community at the lowest nutrient concentration, but only when initiated into this flask. A control treatment without dispersal revealed an even stronger dominance of Alexandrium at the lowest nutrient concentration, indicating that dispersal and the associated nutrient exchange may weaken dinoflagellate dominance under low nutrient conditions. This study presents a first approach to experimentally investigate spatial dynamics and ecological interactions of a harmful dinoflagellate along an environmental gradient in a meta‐ecosystem setup, which has the potential to substantially enhance our understanding of the relevance of dispersal for HAB formation and propagation in combination with local environmental factors.
    Beschreibung: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Schlagwort(e): ddc:579 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Publikationsdatum: 2022-04-04
    Beschreibung: Widespread groundwater pollution with nitrate (NO3−) and the finite and decreasing geogenic NO3− degradation capacity in aquifers require a better understanding of potential treatment methods. This project aimed at exploring and comparing the efficiency of four organic substances as electron donors for heterotrophic denitrification. Circulation column experiments using sediment without NO3− degradation capacity and high agricultural NO3− groundwater were conducted. Acetate, glucose, ascorbic acid, and ethanol were added to these columns in three concentration steps to induce biological denitrification, whereby also temperature dependence of denitrification rates (room temperature and typical groundwater temperature of 10°C) was taken into account. Results show denitrification with all four carbon (C) sources with intensities varying considerably between electron donors. Comparison of the two temperature approaches shows substantial differences between applied organic substances and indicates T as an important variable for denitrification. Ethanol is clearly the most effective electron donor for biodenitrification in groundwater investigated in this study, with a stronger and more effective NO3− degradation at 10°C than at room temperature. In contrast, much higher reaction rates are achieved with glucose at room temperature, compared to 10°C. Denitrification with ascorbic acid is very low at both temperatures; its addition produces biomass which repeatedly led to column clogging. In the entire test series, nitrite (NO2−) accumulation occurred more frequently and in higher concentrations at 10°C. Analysis of microorganisms shows a strong modification in microbial community in reaction to the addition of different organic C as well as between the two temperature approaches.
    Beschreibung: Key Points: Higher denitrification rate with ethanol at 10°C, consequently, reaction kinetics does not generally increase with rising temperature. Addition of organic substances and temperature strongly modify the denitrifying microbial community. Electron donor selection for induced nitrate reduction depends on the groundwater temperature of the region.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:553.79 ; ddc:550.724 ; ddc:628.162
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Publikationsdatum: 2022-04-04
    Beschreibung: Tropical forests contribute about one third to global annual CH4 uptake by soils. Understanding the factors that control the soil‐atmosphere exchange of CH4 at a large scale is a critical step to improve the CH4 flux estimate for tropical soils, which is presently poorly constrained. Since tropical forest degradation often involves shifts in nutrient availabilities, it is critical to evaluate how this will affect soil CH4 flux. Here, we report how nitrogen (N; 50 kg N ha−1 yr−1), phosphorus (P; 10 kg P ha−1 yr−1), and combined N + P additions affect soil CH4 fluxes across an elevation gradient of tropical montane forests. We measured soil CH4 fluxes in a nutrient application experiment at different elevations over a period of 5 years. Nutrient additions increased soil CH4 uptake after 4–5 years of treatment but effects were not uniform across elevations. At 1,000 m, where total soil P was high, we detected mainly N limitation of soil CH4 uptake. At 2,000 m, where total soil P was low, a strong P limitation of soil CH4 uptake was observed. At 3,000 m, where total P was low in the organic layer but high in mineral soil, we found N limitation of soil CH4 uptake. Our results show that projected increases of N and P depositions may increase soil CH4 uptake in tropical montane forests but the direction, magnitude, and timing of the effects will depend on forests' nutrient status and plant‐microbial competition for N and P.
    Beschreibung: Plain Language Summary: CH4 is a potent greenhouse gas that contributes to global warming. Tropical forests are a natural sink of CH4 but increasing nutrient depositions due to industrialization may alter the sink strength of tropical forests. Our results show that projected increases of nitrogen and phosphorus depositions may increase soil CH4 uptake in tropical montane forests but the direction, magnitude, and timing of the effects will depend on forests' nutrients and plant‐microbial competition.
    Beschreibung: Key Points: Projected increases in nitrogen and phosphorus depositions in the tropics will stimulate soil methane uptake in tropical montane forests. The direction, magnitude, and timing of nutrient deposition effects on soil methane uptake will depend on forests' nutrient status. Nutrient limitations on ecosystem processes have to be investigated in actual field conditions.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.org/10.25625/XLNKNK
    Schlagwort(e): ddc:551.9 ; ddc:631.41
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Publikationsdatum: 2022-04-04
    Beschreibung: Rhodolith beds and bioherms formed by ecosystem engineering crustose coralline algae support the northernmost centres of carbonate production, referred to as polar cold‐water carbonate factories. Yet, little is known about biodiversity and recruitment of these hard‐bottom communities or the bioeroders degrading them, and there is a demand for carbonate budgets to include respective rates of polar carbonate build‐up and bioerosion. To address these issues, a 10‐year settlement and bioerosion experiment was carried out at the Arctic Svalbard archipelago in and downslope of a rhodolith bed. The calcifiers recorded on experimental settlement tiles (56 taxa) were dominated by bryozoans, serpulids and foraminiferans. The majority of the bioerosion traces (30 ichnotaxa) were microborings, followed by attachment etchings and grazing traces. Biodiversity metrics show that calcifier diversity and bioerosion ichnodiversity are both elevated in the rhodolith bed, if compared to adjacent aphotic waters, but these differences are statistically insignificant. Accordingly, there were only low to moderate dissimilarities in the calcifier community structure and bioerosion trace assemblages between the two depth stations (46 and 127 m), substrate orientations (up‐ and down‐facing) and substrate types (PVC and limestone), in that order of relevance. In contrast, surface coverage as well as the carbonate accretion and bioerosion rates were all significantly elevated in the rhodolith bed, reflecting higher abundance or size of calcifiers and bioerosion traces. All three measures were highest for up‐facing substrates at 46 m, with a mean coverage of 78.2% (on PVC substrates), a mean accretion rate of 24.6 g m−2  year−1 (PVC), and a mean bioerosion rate of −35.1 g m−2 year−1 (limestone). Differences in these metrics depend on the same order of factors than the community structure. Considering all limestone substrates of the two platforms, carbonate accretion and bioerosion were nearly in balance at a net rate of −2.5 g m−2 year−1. A latitudinal comparison with previous settlement studies in the North Atlantic suggests that despite the harsh polar environment there is neither a depletion in the diversity of hard‐bottom calcifier communities nor in the ichnodiversity of grazing traces, attachment etchings and microborings formed by organotrophs. In contrast, microborings produced by phototrophs are strongly depleted because of limitations in the availability of light (condensed photic zonation, polar night, shading by sea ice). Also, macroborings were almost absent, surprisingly. With respect to carbonate production, the Svalbard carbonate factory marks the low end of a latitudinal gradient while bioerosion rates are similar or even higher than at comparable depth or photic regime at lower latitudes, although this might not apply to shallow euphotic waters (not covered in our experiment), given the observed depletion in bioeroding microphytes and macroborers. While echinoid grazing is particularly relevant for the bioerosion in the rhodolith bed, respective rates are far lower than those reported from tropical shallow‐water coral reefs. The slow pace of carbonate production but relatively high rates of bioerosion (both promoted by low carbonate supersaturation states in Arctic waters), in concert with high retention of skeletal carbonates on the seafloor and no calcite cements forming in open pore space created by microborers, suggest a low fossilisation potential for polar carbonates, such as those formed in the Mosselbukta rhodolith beds.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:593.6 ; ddc:528.58
    Sprache: Englisch
    Materialart: doc-type:article
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  • 20
    Publikationsdatum: 2022-04-04
    Beschreibung: Focused fluid flow shapes the evolution of marine sedimentary basins by transferring fluids and pressure across geological formations. Vertical fluid conduits may form where localized overpressure breaches a cap rock (permeability barrier) and thereby transports overpressured fluids towards shallower reservoirs or the surface. Field outcrops of an Eocene fluid flow system at Pobiti Kamani and Beloslav Quarry (ca 15 km west of Varna, Bulgaria) reveal large carbonate‐cemented conduits, which formed in highly permeable, unconsolidated, marine sands of the northern Tethys Margin. An uncrewed aerial vehicle with an RGB sensor camera produces ortho‐rectified image mosaics, digital elevation models and point clouds of the two kilometre‐scale outcrop areas. Based on these data, geological field observations and petrological analysis of rock/core samples, fractures and vertical fluid conduits were mapped and analyzed with centimetre accuracy. The results show that both outcrops comprise several hundred carbonate‐cemented fluid conduits (pipes), oriented perpendicular to bedding, and at least seven bedding‐parallel calcite cemented interbeds which differ from the hosting sand formation only by their increased amount of cementation. The observations show that carbonate precipitation likely initiated around areas of focused fluid flow, where methane entered the formation from the underlying fractured subsurface. These first carbonates formed the outer walls of the pipes and continued to grow inward, leading to self‐sustaining and self‐reinforcing focused fluid flow. The results, supported by literature‐based carbon and oxygen isotope analyses of the carbonates, indicate that ambient seawater and advected fresh/brackish water were involved in the carbonate precipitation by microbial methane oxidation. Similar structures may also form in modern settings where focused fluid flow advects fluids into overlying sand‐dominated formations, which has wide implications for the understanding of how focusing of fluids works in sedimentary basins with broad consequences for the migration of water, oil and gas.
    Beschreibung: Integrated School of Ocean Sciences (ISOS) Kiel
    Beschreibung: European Union’s Horizon 2020 http://dx.doi.org/10.13039/100010661
    Beschreibung: Bulgarian Science Fund
    Schlagwort(e): ddc:551
    Sprache: Englisch
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  • 21
    Publikationsdatum: 2022-04-04
    Beschreibung: The influence of the exceptionally strong typhoon Mangkhut on the availability of nutrients and changes in primary production were studied in the northern South China Sea in September 2018. A tight station grid was sampled to analyze major nutrients, chlorophyll_a, particulate and dissolved organic carbon and nitrogen. Based on interpolated profiles, nutrients and organic matter budgets were determined for the upper 100 m of the water column prior to and after Mangkhut's passage. An upper layer of 100 m was found to reflect the important changes by the typhoon. Considerable differences between the on‐shelf, shelf edge and the deep‐sea stations were determined. Nitrate and phosphate increased by about 80% and 36% on the shelf, respectively, and both by almost 40% at the shelf edge. The open deep‐sea part of the study area reflects some deviating results that may be caused by just displacement of water or by mixing water of different origin. However, right on Mangkhut's track on the shelf even contact between surface waters and bottom waters was enabled, increasing phosphate and silicate, but declining nitrate. The inventory of organic carbon of the upper 100 m of the study area (138,000 km2) of 92 Gmol had increased within a few days after the typhoon's passage by 5 Gmol on the shelf and about 2 Gmol in the shelf edge area. Chlorophyll_a doubled during our stay and might have reached a factor of 3 increase in the subsequent time by nitrate supply and excess phosphate.
    Beschreibung: Plain Language Summary: The influence of the super typhoon Mangkhut on the waters of the northern South China Sea was studied in September 2018. Nutrients and organic material were measured on 63 stations from the Chinese research vessel HAI YANG DI ZHI SHI HAO. Amounts of nutrients and biogenic matter were calculated for the on‐shelf, shelf edge and deep‐sea stations for the pre‐ and post‐Mangkhut period. An important finding was that the stations of the different areas, on‐shelf, shelf edge and the deep‐sea appeared to be differently impacted by Mangkhut. Even differences between the stations right on its track and in the other parts of the study area were found. In general, nutrients were supplied in enormous amounts and caused immediate algae growth. Moreover, enough nutrients were supplied to support algae growth for a couple of weeks. In summary, it was found that Manghut's upper water column mixing and shifting caused an almost tripling of primary production compared to the normal situation.
    Beschreibung: Key Points: The typhoon Mangkhut clearly impacted the water column differently on the continental shelf, at the shelf edge and in the deep sea. On Mangkhut's track a maximum nitrate supply of 162 mmol m−2 was caused by induced upwelling at the shelf edge. The chlorophyll inventory of 2.8 Gg was almost tripled by contributing 4.7 Gg estimated from an additional nutrient supply.
    Beschreibung: Federal Ministry of Education and Research, BMBF http://dx.doi.org/10.13039/501100002347
    Beschreibung: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Beschreibung: https://doi.pangaea.de/10.1594/PANGAEA.936352
    Beschreibung: https://doi.pangaea.de/10.1594/PANGAEA.936096
    Schlagwort(e): ddc:577.7
    Sprache: Englisch
    Materialart: doc-type:article
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  • 22
    Publikationsdatum: 2022-04-04
    Beschreibung: Microbial organic matter decomposition is a critical ecosystem function, which can be negatively affected by chemicals. Although the majority of organic matter is stored in sediments, the impact of chemicals has exclusively been studied in benthic systems. To address this knowledge gap, we assessed the impact of a fungicide mixture at three concentrations on the decomposition of black alder leaves in the benthic and hyporheic zone. We targeted two sediment treatments characterized by fine and coarse grain sizes (1–2 vs. 2–4 mm). Besides microbial communities' functioning (i.e., decomposition), we determined their structure through microbial biomass estimates and community composition. In absence of fungicides, leaf decomposition, microbial biomass estimates and fungal sporulation were lower in the hyporheic zone, while the importance of bacteria was elevated. Leaf decomposition was reduced (40%) under fungicide exposure in fine sediment with an effect size more than twice as high as in the benthic zone (15%). These differences are likely triggered by the lower hydraulic conductivity in the hyporheic zone influencing microbial dispersal as well as oxygen and nutrient fluxes. Since insights from the benthic zone are not easily transferable, these results indicate that the hyporheic zone requires a higher recognition with regard to ecotoxicological effects on organic matter decomposition.
    Beschreibung: German Research Foundation, Project AQUA‐REG http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:550.724 ; ddc:579
    Sprache: Englisch
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  • 23
    Publikationsdatum: 2022-04-04
    Beschreibung: Building on recent developments in phase‐field modeling of structural diagenesis, we present an analysis of single‐seal syntaxial calcite vein microstructure in a variety of limestones. We focus on the effects of fracture aperture, intergranular versus transgranular fracturing, crystal habit and the presence of second phases in the host rock, to systematically investigate a simplified set of models covering the main classes of limestone in 2D. We incorporate the kinematic process of growth competition between differently oriented crystals, growth rate anisotropy between rough and faceted crystal surfaces and different growth rates on intergranular to transgranular fractures. Results show that within the considered parameter space we can reproduce a wide range of vein microstructures in limestone known in nature, such as stretched crystals, wide‐blocky veins, and elongated crystals. We identify five archetypes of vein microstructures in limestones, which are diagnostic for different kinematics and evolution of transport processes and illustrate the effect of key parameters in microstructure maps. We show how syntaxial veins with median line form after intergranular fracturing, while stretched crystals indicate transgranular fracturing. Intergranular fracturing leads to stronger growth competition and more prominent CPO in syntaxial veins. Our results can be extended to 3D to include multiple crack‐seal events, pore‐space cementation and simulation of fluid flow, providing a generic platform for modeling structural diagenesis in limestones.
    Beschreibung: Plain Language Summary: Fractures are ubiquitous in in the earth crust, forming important pathways for geothermal fluids. This fluid is often supersaturated, allowing crystals to grow in the open fractures which leads to fracture healing over time. During this self‐sealing of the fractured rock the permeability and strength of the rock change with many important consequences for subsurface engineering. In this study, we simulate the complex growth process and show how different crystal structures (e.g., stretched, blocky) form in open fractures in different types of limestone and compare our results to natural rock samples. We test different factors on how they affect the crystal morphology as fracture type (crack cuts though grain or along grain boundaries), opening width of the fracture, and coated grain surfaces (which can reduce the crystal growth rate). We are able to reproduce a wide range of crystal structures which occur in natural limestone, and present a framework for interpreting the evolution process of calcite veins in limestones. The systematic data analysis provides valuable insight in structure‐property linkages enabling a prediction of fracture healing mechanisms.
    Beschreibung: Key Points: Systematic phase‐field study captures formation of a wide range of single seal veins in limestones and provides insight to fracture healing. Effects of different parameters are illustrated in morphology maps and show diagnostic microstructures. Transgranular fracturing leads to stretched crystals and intergranular fracturing leads to more prominent CPO in syntaxial veins.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.org/10.5281/zenodo.4597529
    Schlagwort(e): ddc:548
    Sprache: Englisch
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  • 24
    Publikationsdatum: 2022-04-04
    Beschreibung: Uncrewed aerial systems (UAS), combined with structure‐from‐motion photogrammetry, has already proven to be very powerful for a wide range of geoscience applications and different types of UAS are used for scientific and commercial purposes. However, the impact of the UAS used on the accuracy of the point clouds derived is not fully understood, especially for the quantitative analysis of geomorphic changes in complex terrain. Therefore, in this study, we aim to quantify the magnitude of systematic and random error in digital elevation models derived from four commonly used UAS (XR6/Sony α6000, Inspire 2/X4s, Phantom 4 Pro+, Mavic Pro) following different flight patterns. The vertical error of each elevation model is evaluated through comparison with 156 GNSS reference points and the normal distribution and spatial correlation of errors are analysed. Differences in mean errors (−0.4 to −1.8 cm) for the XR6, Inspire 2 and Phantom 4 Pro are significant but not relevant for most geomorphological applications. The Mavic Pro shows lower accuracies with mean errors up to 4.3 cm, thus showing a higher influence of random errors. QQ plots revealed a deviation of errors from a normal distribution in almost all data. All UAS data except Mavic Pro exhibit a pure nugget semivariogram, suggesting spatially uncorrelated errors. Compared to the other UAS, the Mavic Pro data show trends (i.e. differences increase with distance across the survey—doming) and the range of semivariances is 10 times greater. The lower accuracy of Mavic Pro can be attributed to the lower GSD at the same flight altitude and most likely, the rolling shutter sensor has an effect on the accuracy of the camera calibration. Overall, our study shows that accuracies depend highly on the chosen data sampling strategy and that the survey design used here is not suitable for calibrating all types of UAS camera equally.
    Beschreibung: In this study, we aim to quantify the magnitude of systematic and random error in digital elevation models derived from four commonly used UAS (XR6/Sony α6000, Inspire 2/X4s, Phantom 4 Pro+, Mavic Pro) following different flight patterns. Differences in mean errors (−0.4 to −1.8 cm) for the XR6, Inspire 2 and Phantom 4 Pro are significant but not relevant for most geomorphological applications. Compared to the other UAS, the Mavic Pro data show trends (i.e., differences increase with distance across the survey—doming), and the range of semivariances is 10 times greater. The lower accuracy of Mavic Pro can be attributed to the lower GSD at the same flight altitude, and most likely, the rolling shutter sensor has an effect on the accuracy of the camera calibration.
    Schlagwort(e): ddc:526.982
    Sprache: Englisch
    Materialart: doc-type:article
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  • 25
    Publikationsdatum: 2022-04-04
    Beschreibung: We report the recovery and characterization of a new urban micrometeorite collection derived from the rooftop of an industrial building in Germany. We identified 315 micrometeorites (diameter: 55–515 µm, size peak: ˜150 µm, size distribution slope exponent: −2.62). They are predominantly S‐type cosmic spherules (97.2%) but also two G‐type spherules (0.6%), an unmelted coarse‐grained single‐mineral micrometeorite, and eight scoriaceous particles (2.5%) or particles transitional between scoriaceous micrometeorites and porphyritic spherules. Their analysis details how the magnetite rim on partially melted micrometeorites is progressively diluted as the melt fraction increases during heating. At least 10 micrometeorites contain platinum group nuggets (PGNs). They have chondritic compositions but are depleted in volatile Pd. However, a single nugget preserves chondritic Pd concentrations. We suggest that an Fe‐Ni‐S bead originally containing the PGN escaped its host cavity and wet the particle exterior, creating an Fe‐rich melt that protected the nugget from evaporation. This melt layer oxidized forming magnetite—indicating that wetting events can affect the texture and composition of micrometeorites. Utilizing the well‐constrained surface area (8400 m2) and rooftop age (21 yr), we attempted the first global mass flux estimate based on urban micrometeorite data. This produced anomalously low values (13.4 t yr–1), even when correcting for losses due to sample processing (〈89.7 t yr–1). Our value is approximately two orders of magnitude lower than previous estimates, indicating that 〉99% of particles are missing, having been lost via drainage and cleaning. Rooftop collection sites have limited potential for mass flux calculations unless problems of loss can be resolved. However, urban micrometeorite collections have other advantages, notably exceptionally well‐preserved particles with extremely young terrestrial ages and the ability to extract many micrometeorites from accessible sites. Urban micrometeorites should be considered complementary to Antarctic and deep‐sea collections with potential for citizen science and educational exploitation.
    Schlagwort(e): ddc:549.112
    Sprache: Englisch
    Materialart: doc-type:article
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  • 26
    Publikationsdatum: 2022-04-04
    Beschreibung: Observations in polar regions show that sea ice deformations are often narrow linear features. These long bands of deformations are referred to as Linear Kinematic Features (LKFs). Viscous‐plastic sea ice models have the capability to simulate LKFs and more generally sea ice deformations. Moreover, viscous‐plastic models simulate a larger number and more refined LKFs as the spatial resolution is increased. Besides grid spacing, other aspects of a numerical implementation, such as the placement of velocities and the associated degrees of freedom, may impact the formation of simulated LKFs. To explore these effects this study compares numerical solutions of sea ice models with different velocity staggering in a benchmark problem. Discretizations based on A‐,B‐, and C‐grid systems on quadrilateral meshes have similar resolution properties as an approximation with an A‐grid staggering on triangular grids (with the same total number of vertices). CD‐grid approximations with a given grid spacing have properties, specifically the number and length of simulated LKFs, that are qualitatively similar to approximations on conventional Arakawa A‐grid, B‐grid, and C‐grid approaches with half the grid spacing or less, making the CD‐discretization more efficient with respect to grid resolution. One reason for this behavior is the fact that the CD‐grid approach has a higher number of degrees of freedom to discretize the velocity field. The higher effective resolution of the CD‐discretization makes it an attractive alternative to conventional discretizations.
    Beschreibung: Plain Language Summary: Sea ice in the Arctic and Antarctic Oceans plays an important role in the exchange of heat and freshwater between the atmosphere and the ocean and hence in the climate in general. Satellite observations of polar regions show that the ice drift sometimes produces long features that are either cracks (leads) and zones of thicker sea ice (pressure ridges). This phenomenon is called deformation. It is mathematically described by the non‐uniform way in which the ice moves. For numerical models of sea ice motion it is difficult to represent this deformation accurately. Details of the numerics may affect the way these models simulate leads and ridges, their number and length. Specifically, we find by comparing different numerical models, that the way the model variables are ordered on a computational grid to solve the mathematical equations of sea ice motion has an effect of how many deformation features can be represented on a grid with a given spacing between grid points. A new discretization (ordering of model variables) turns out to resolve more details of the approximated field than traditional methods.
    Beschreibung: Key Points: The placement of the sea ice velocity has a mayor influence on the number of simulated linear kinematic features (LKFs). The CD‐grid resolves twice as many LKFs compared to A, B, C‐grids. A, B, C‐grids on quadrilateral meshes resolve a similar number of LKFs as A‐grids on triangular meshes (with the same total number of nodes).
    Schlagwort(e): ddc:550 ; ddc:551.343
    Sprache: Englisch
    Materialart: doc-type:article
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  • 27
    Publikationsdatum: 2022-04-04
    Beschreibung: Nutrients limiting phytoplankton growth in the ocean are a critical control on ocean productivity and can underpin predicted responses to climate change. The extensive western subtropical North Pacific is assumed to be under strong nitrogen limitation, but this is not well supported by experimental evidence. Here, we report the results of 14 factorial nitrogen–phosphorus–iron addition experiments through the Philippine Sea, which demonstrate a gradient from nitrogen limitation in the north to nitrogen–iron co‐limitation in the south. While nitrogen limited sites responded weakly to nutrient supply, co‐limited sites bloomed with up to ~60‐fold increases in chlorophyll a biomass that was dominated by initially undetectable diatoms. The transition in limiting nutrients and phytoplankton growth capacity was driven by a gradient in deep water nutrient supply, which was undetectable in surface concentration fields. We hypothesize that this large‐scale phytoplankton response gradient is both climate sensitive and potentially important for regulating the distribution of predatory fish.
    Beschreibung: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Schlagwort(e): ddc:577.7 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
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  • 28
    Publikationsdatum: 2022-04-04
    Beschreibung: Organisms are exposed to ever‐changing complex mixtures of chemicals over the course of their lifetime. The need to more comprehensively describe this exposure and relate it to adverse health effects has led to formulation of the exposome concept in human toxicology. Whether this concept has utility in the context of environmental hazard and risk assessment has not been discussed in detail. In this Critical Perspective, we propose—by analogy to the human exposome—to define the eco‐exposome as the totality of the internal exposure (anthropogenic and natural chemicals, their biotransformation products or adducts, and endogenous signaling molecules that may be sensitive to an anthropogenic chemical exposure) over the lifetime of an ecologically relevant organism. We describe how targeted and nontargeted chemical analyses and bioassays can be employed to characterize this exposure and discuss how the adverse outcome pathway concept could be used to link this exposure to adverse effects. Available methods, their limitations, and/or requirement for improvements for practical application of the eco‐exposome concept are discussed. Even though analysis of the eco‐exposome can be resource‐intensive and challenging, new approaches and technologies make this assessment increasingly feasible. Furthermore, an improved understanding of mechanistic relationships between external chemical exposure(s), internal chemical exposure(s), and biological effects could result in the development of proxies, that is, relatively simple chemical and biological measurements that could be used to complement internal exposure assessment or infer the internal exposure when it is difficult to measure. Environ Toxicol Chem 2022;41:30–45. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Beschreibung: Illustration of the eco‐exposome assessment and how chemical analysis and bioassays could be used to estimate internal exposure. MIE = molecular initiation event; KE = key event; AO = adverse outcome.
    Beschreibung: DAAD German academic exchange service
    Schlagwort(e): ddc:577.14
    Sprache: Englisch
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  • 29
    facet.materialart.
    Unbekannt
    John Wiley & Sons, Inc. | Hoboken, USA
    Publikationsdatum: 2022-04-04
    Beschreibung: In 1883, Theodor Wilhelm Engelmann, a German scientist, wrote his essay “color and assimilation” (Ger.: “Farbe und Assimilation”) describing the state of the art in photosynthesis research, his recent findings, and further assumptions based upon his presented results. Nearly 140 years later, many of his assumptions were proven correct. By his still well‐known bacteria experiments using aerotactic, heterotrophic bacteria, he identified the chloroplasts as the location in which photosynthesis and oxygen production takes place. Furthermore, by evaluating the effects of different light spectra, he constructed the first action spectra that demonstrated the implication of the “green gap” of chlorophylls. He further posited that accessory photosynthetic pigments existed to extend the absorption range of chlorophyll. Although infrequently cited, his work was foundational for current ecological research of the vertical appearance of algae species within the underwater gradient in light spectrum due to specific harvesting of different light spectra, hence complementary chromatic adaptation of communities. This short retrospective highlights this piece of literature that represents an early step toward our current understanding of ecological competition for light spectra.
    Schlagwort(e): ddc:572.46 ; ddc:570.9
    Sprache: Englisch
    Materialart: doc-type:article
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  • 30
    Publikationsdatum: 2022-04-01
    Beschreibung: The Data Science Symposium at Haus der Wissenschaft on 8/9 November 2021 in Bremen was the 6th Symposium in this series since 2017.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Miscellaneous , notRev
    Format: application/pdf
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  • 31
    Publikationsdatum: 2022-04-04
    Beschreibung: Currently, little is known about the population identity of fin whales (Balaenoptera physalus) in Antarctic waters but initial analyses of acoustic recordings from the Southern Ocean (SO) have shown that fin whale calls differ between regions, possibly representing different fin whale populations. In the Atlantic Sector of the Southern Ocean, the typical fin whale 20-Hz song is often accompanied by simultaneous higher frequency (HF) component at around 89Hz or 99Hz. However, the distribution of these call types throughout the area and whether there is a clear spatial separation between these call types is so far unknown. In this study fin whale calls were examined between two locations, the Greenwich Meridian and Elephant Island across the Weddell Sea (from 2009, 2011, 2013, and 2015) to gain further insights into the connections between fin whales in this region. The HF call component was found to be significantly (p-value 〈 2.2e^-16) unique in its frequency at the two locations with 99Hz (97.14Hz ± 3.19) at Greenwich Meridian and 86Hz (86.26Hz ± 1.36) at Elephant Island. The inter-pulse interval (IPI) of both low frequency (LF) (20-Hz) and HF calls were also found to differ between geographic regions, with a median IPI of 14.5 seconds at Elephant Island and median IPI around 10 seconds at Greenwich Meridian. Variation in song IPIs were also investigated between geographic locations, Elephant Island was determined to have a majority singlet song type and Greenwich Meridian was found to have mostly triplet songs. The occurrence of HF and LF calls showed a strong positive correlation, indicating that both call components are produced simultaneously. The characteristic elements for fin whale calls examined in this study all indicate that the fin whale calls recorded at Elephant Island and Greenwich Meridian belong to two distinct acoustic populations. An understanding of how potentially distinct fin whale stocks utilize different geographic regions is fundamental for management and conservation measures aiming to improve the conservation status of this vulnerable species.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Thesis , notRev
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  • 32
    Publikationsdatum: 2022-04-07
    Beschreibung: The decomposition of thawing permafrost organic matter (OM) to the greenhouse gases (GHG) carbon dioxide (CO2) and methane forms a positive feedback to global climate change. Data on in situ GHG fluxes from thawing permafrost OM are scarce and OM degradability is largely unknown, causing high uncertainties in the permafrost‐carbon climate feedback. We combined in situ CO2 and methane flux measurements at an abrupt permafrost thaw feature with laboratory incubations and dynamic modeling to quantify annual CO2 release from thawing permafrost OM, estimate its in situ degradability and evaluate the explanatory power of incubation experiments. In July 2016 and 2019, CO2 fluxes ranged between 0.24 and 2.6 g CO2‐C m−2 d−1. Methane fluxes were low, which coincided with the absence of active methanogens in the Pleistocene permafrost. CO2 fluxes were lower three years after initial thaw after normalizing these fluxes to thawed carbon, indicating the depletion of labile carbon. Higher CO2 fluxes from thawing Pleistocene permafrost than from Holocene permafrost indicate OM preservation for millennia and give evidence that microbial activity in the permafrost was not substantial. Short‐term incubations overestimated in situ CO2 fluxes but underestimated methane fluxes. Two independent models simulated median annual CO2 fluxes of 160 and 184 g CO2‐C m−2 from the thaw slump, which include 25%–31% CO2 emissions during winter. Annual CO2 fluxes represent 0.8% of the carbon pool thawed in the surface soil. Our results demonstrate the potential of abrupt thaw processes to transform the tundra from carbon neutral into a substantial GHG source.
    Beschreibung: Plain Language Summary: Thawing of permanently frozen soils (permafrost) in the northern hemisphere forms a threat to global climate since these soils contain large amounts of frozen organic carbon, which might be decomposed to the greenhouse gases (GHGs) carbon dioxide (CO2) and methane upon thaw. How fast these GHGs are produced is largely unknown, since field observations of greenhouse gas fluxes from thawing permafrost are too sparse. Consequently, simulations on the effect of thawing permafrost soils on future climate are highly uncertain. We measured CO2 and methane fluxes from soils affected by abrupt permafrost thaw in Siberia during two summer seasons. We used these field observations and long‐term incubation data to calibrate two models that simulate the CO2 release over a whole year. We found that greenhouse gas fluxes were dominated by CO2 and that the minor importance of methane was due to the absence of methane producing microorganisms in the Pleistocene permafrost. The CO2 release in the first year accounted for 0.8% of thawed permafrost carbon but decomposition rates decreased after the depletion of the rapidly decomposable organic matter. Abrupt permafrost thaw turned the tundra into a substantial source of CO2, of which 25%–31% was released in the non‐growing season.
    Beschreibung: Key Points: Abrupt permafrost thaw turned the tundra into a substantial annual source of CO2 of which 25%–31% were released in the non‐growing season. About 0.8% of thawed permafrost carbon was decomposed to CO2 in one year but decomposition rates declined after the loss of labile carbon. Methane contributed a minor fraction to total greenhouse gas fluxes also because of a low methanogen abundance in Pleistocene permafrost.
    Beschreibung: German Ministry for Education and Research
    Beschreibung: German Research Foundation
    Beschreibung: https://doi.org/10.5281/zenodo.5584710
    Schlagwort(e): ddc:551
    Sprache: Englisch
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  • 33
    facet.materialart.
    Unbekannt
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Publikationsdatum: 2022-04-07
    Beschreibung: Incoherent diffractive imaging (IDI) promises structural analysis with atomic resolution based on intensity interferometry of pulsed X‐ray fluorescence emission. However, its experimental realization is still pending and a comprehensive theory of contrast formation has not been established to date. Explicit expressions are derived for the equal‐pulse two‐point intensity correlations, as the principal measured quantity of IDI, with full control of the prefactors, based on a simple model of stochastic fluorescence emission. The model considers the photon detection statistics, the finite temporal coherence of the individual emissions, as well as the geometry of the scattering volume. The implications are interpreted in view of the most relevant quantities, including the fluorescence lifetime, the excitation pulse, as well as the extent of the scattering volume and pixel size. Importantly, the spatiotemporal overlap between any two emissions in the sample can be identified as a crucial factor limiting the contrast and its dependency on the sample size can be derived. The paper gives rigorous estimates for the optimum sample size, the maximum photon yield and the expected signal‐to‐noise ratio under optimal conditions. Based on these estimates, the feasibility of IDI experiments for plausible experimental parameters is discussed. It is shown in particular that the mean number of photons per detector pixel which can be achieved with X‐ray fluorescence is severely limited and as a consequence imposes restrictive constraints on possible applications.
    Beschreibung: Starting from a simple model of stochastic fluorescence emission, a theory is derived of contrast formation and signal‐to‐noise ratio for incoherent diffractive imaging; its feasibility for plausible experimental parameters is discussed. image
    Schlagwort(e): ddc:548
    Sprache: Englisch
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  • 34
    Publikationsdatum: 2022-04-07
    Beschreibung: Hydrogen isotope ratios of sedimentary leaf waxes (δ2HWax values) are increasingly used to reconstruct past hydroclimate. Here, we add δ2HWax values from 19 lakes and four swamps on 15 tropical Pacific islands to an updated global compilation of published data from surface sediments and soils. Globally, there is a strong positive linear correlation between δ2H values of mean annual precipitation (δ2HP values) and the leaf waxes n‐C29‐alkane (R2 = 0.74, n = 665) and n‐C28‐acid (R2 = 0.74, n = 242). Tropical Pacific δ2HWax values fall within the predicted range of values based on the global calibration, and the largest residuals from the global regression line are no greater than those observed elsewhere, despite large uncertainties in δ2HP values at some Pacific sites. However, tropical Pacific δ2HWax values in isolation are not correlated with estimated δ2HP values from isoscapes or from isotope‐enabled general circulation models. Palynological analyses from these same Pacific sediment samples suggest no systematic relationship between any particular type of pollen distribution and deviations from the global calibration line. Rather, the poor correlations observed in the tropical Pacific are likely a function of the small range of δ2HP values relative to the typical residuals around the global calibration line. Our results suggest that δ2HWax values are currently most suitable for use in detecting large changes in precipitation in the tropical Pacific and elsewhere, but that ample room for improving this threshold exits in both improved understanding of δ2H variability in plants, as well as in precipitation.
    Beschreibung: Plain Language Summary: Past precipitation patterns are difficult to reconstruct, limiting our ability to understand Earth’s climate system. Geochemists reconstruct past precipitation by measuring the amount of heavy hydrogen naturally incorporated into the waxy coating of leaves, which is preserved in mud that accumulates in lakes, soils, and oceans. Heavy hydrogen in leaf waxes is strongly correlated with local precipitation, allowing us to learn about rainfall intensity, temperature, and cloud movement. However, no existing calibration studies include sites from the tropical Pacific, home to the most intense rainfall on the planet and populations that rely on rain for drinking water and farming. We measured heavy hydrogen in leaf waxes from tropical Pacific islands and show that although values are within the global calibration error, no precipitation relationship exists within the region. Plant type distributions do not explain the lack of correlation, which is best attributed to poorly constrained estimates of heavy hydrogen in local rain and the relatively small range of variability within the region. At present, heavy hydrogen from ancient leaf waxes can show large changes in past precipitation, but improved process‐level understanding is needed to use this tool to understand smaller changes in the tropical Pacific and elsewhere.
    Beschreibung: Key Points: Leaf wax 2H/1H ratios are correlated with mean annual precipitation 2H/1H ratios globally, but not in the tropical Pacific. Deviations from the global relationship between precipitation leaf wax 2H/1H ratios cannot be predicted from palynological assemblages. Small range and large uncertainties in estimates of tropical Pacific precipitation 2H/1H ratios likely account for poor correlations.
    Beschreibung: Swiss National Science Foundation
    Beschreibung: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Beschreibung: Natural Environment Research Council (NERC) http://dx.doi.org/10.13039/501100000270
    Beschreibung: Department of Education and Training, Australian Research Council (ARC) http://dx.doi.org/10.13039/501100000923
    Beschreibung: http://10.0.15.89/ethz-b-000412154
    Schlagwort(e): ddc:551 ; ddc:577.7
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Publikationsdatum: 2022-04-07
    Beschreibung: Many large rivers used for navigation have lost their hydromorphological heterogeneity, which has led to the widespread loss of native biodiversity and the concurrent establishment of non‐native communities. While the effects on biodiversity are well‐described, we know little about how the loss of natural habitats and the restructuring of communities cumulate into effects on riverine food webs. We constructed binary and ingestion webs for benthic macroinvertebrates and their resources in the Elbe River (Germany) and compared if food chain length, food web complexity, robustness, ingestion rates, and consumer‐resource interaction strength differ among three shoreline engineering practices. Food webs at profoundly altered shorelines were significantly less complex and had significantly shorter food chains than the food web at the semi‐natural shoreline. However, food web robustness to a simulated loss of species was comparable at all shorelines. Total ingestion rates were up to eight times lower at highly altered shorelines due to significantly lower ingestion rates by native species. Predator–prey interaction strength was comparable among shorelines due to higher shares of non‐native predators, indicating that non‐native predators can be functionally equivalent to native predators. We attributed the observed food web differences to the absence of complex habitats at profoundly altered shorelines and the accompanied absence of specialized consumers. Our study provides empirical evidence that hydromorphological modifications reduce the efficiency of food webs to control organic matter dynamics and may ultimately affect the provisioning of riverine ecosystem services.
    Schlagwort(e): ddc:339.95 ; ddc:551.483
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Publikationsdatum: 2022-04-07
    Beschreibung: Inland waters receive and process large amounts of colored organic matter from the terrestrial surroundings. These inputs dramatically affect the chemical, physical, and biological properties of water bodies, as well as their roles as global carbon sinks and sources. However, manipulative studies, especially at ecosystem scale, require large amounts of dissolved organic matter with optical and chemical properties resembling indigenous organic matter. Here, we compared the impacts of two leonardite products (HuminFeed and SuperHume) and a freshly derived reverse osmosis concentrate of organic matter in a set of comprehensive mesocosm‐ and laboratory‐scale experiments and analyses. The chemical properties of the reverse osmosis concentrate and the leonardite products were very different, with leonardite products being low and the reverse osmosis concentrate being high in carboxylic functional groups. Light had a strong impact on the properties of leonardite products, including loss of color and increased particle formation. HuminFeed presented a substantial impact on microbial communities under light conditions, where bacterial production was stimulated and community composition modified, while in dark potential inhibition of bacterial processes was detected. While none of the browning agents inhibited the growth of the tested phytoplankton Gonyostomum semen, HuminFeed had detrimental effects on zooplankton abundance and Daphnia reproduction. We conclude that the effects of browning agents extracted from leonardite, particularly HuminFeed, are in sharp contrast to those originating from terrestrially derived dissolved organic matter. Hence, they should be used with great caution in experimental studies on the consequences of terrestrial carbon for aquatic systems.
    Beschreibung: Marie Curie International Outgoing Fellowship
    Beschreibung: Swedish Research Council Formas http://dx.doi.org/10.13039/501100001862
    Beschreibung: Knut and Alice Wallenberg Foundation http://dx.doi.org/10.13039/501100004063
    Schlagwort(e): ddc:551.48 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
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    Unbekannt
    Publikationsdatum: 2022-04-01
    Beschreibung: Many countries have applied many measures, including preventing inappropriate activities in areas where drinking water is abstracted to protect drinking water resources. However, reaching good water quality based on human health has not been achieved in drinking water basins. Drinking‐Water Protected Areas Determination has been defined as a powerful protection method to restrict inappropriate activities affecting water quality and quantity. These areas are determined based on basin properties to provide sustainable drinking water management. This study aims to present a framework for drinking water protection by giving methodological study steps. Strengths, deficiencies and inadequacies in drinking water protection practices were shown by examining the implementations of Turkey and European Union member countries. Thus, by adding new methods to these applications, a standard approach was created to be applied to each different drinking water basin.
    Schlagwort(e): ddc:363.61 ; ddc:628.1
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Publikationsdatum: 2022-04-01
    Beschreibung: Using a household and plot‐level survey conducted in Ethiopia, this study analyses the difference in farmers' adoption of sustainable land management (SLM) practices between their rainfed and irrigated plots. The paper also investigates the varying influence of different types of irrigation water management systems and associated irrigation technologies on the adoption of SLM practices in irrigated plots. After controlling for heterogeneity among different irrigation water management systems and technologies, we found that access to irrigation play major role in enhancing farmers' motivation to adopt more SLM practices. Furthermore, the combined effect of irrigation water management system and irrigation technology on type and number of SLM practices adopted is quite varied and very significant. The evidence highlights that farmers adopt more SLM practices in their plots with pump irrigation compared with those plots where gravity irrigation is applied because pump irrigation systems enhance complementarities with SLM practices. Finally, the findings underscore that the type of irrigation water management and the irrigation technology applied play an important role in restoring degraded lands and maintaining soil fertility, even when farmers' adoption of irrigation was not explicitly triggered by concerns for soil health.
    Beschreibung: Center for Development Research (ZEF), University of Bonn
    Beschreibung: CGIAR Research Program on Water, Land, and Ecosystems
    Beschreibung: Deutscher Akademischer Austauschdienst (DAAD) http://dx.doi.org/10.13039/501100001655
    Beschreibung: Dr. Hermann Eiselen Doctoral Program of the Foundation Fiat
    Beschreibung: Federal Ministry for Economic Cooperation and Development (BMZ) of Germany, The Water‐Energy‐Food Nexus: Global, Basin and Local Case Studies of Resource Use Efficiency Under Growing Natural Resource Scarcity
    Schlagwort(e): ddc:631
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Publikationsdatum: 2022-04-01
    Beschreibung: Recent advances in geostationary imaging have enabled the derivation of high spatiotemporal‐resolution cloud‐motion winds for the study of mesoscale unsteady flows. Due to the general absence of ground truth, the quality assessment of satellite winds is challenging. In the current limited practice, straightforward plausibility checks on the smoothness of the retrieved wind field or tests on aggregated trends such as the mean velocity components are applied for quality control. In this study, we demonstrate additional diagnostic tools based on feature extraction from the retrieved velocity field. Lagrangian Coherent Structures (LCS), such as vortices and transport barriers, guide and constrain the emergence of cloud patterns. Evaluating the alignment of the extracted LCS with the observed cloud patterns can potentially serve as a test of the retrieved wind field to adequately explain the time‐dependent dynamics. We discuss the suitability and expressiveness of direct, geometry‐based, texture‐based, and feature‐based flow visualization methods for the quality assessment of high spatiotemporal‐resolution winds through the real‐world example of an atmospheric Kármán vortex street and its laboratory archetype, the 2D cylinder flow.
    Beschreibung: Key Points: Recently developed high‐cadence geostationary satellite winds enable the Lagrangian analysis of unsteady island wake flows. Good correspondence between Lagrangian Coherent Structures and observed cloud patterns indirectly confirms the fidelity of fluid dynamics. Discussion of benefits and pitfalls of common flow visualization techniques for the analysis of fluid dynamics.
    Beschreibung: Swiss National Science Foundation
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.org/10.5281/zenodo.3534276
    Beschreibung: https://www.avl.class.noaa.gov/
    Beschreibung: https://github.com/tobguent/vislcs-guadalupe
    Schlagwort(e): ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Publikationsdatum: 2022-04-01
    Beschreibung: The transient climate response (TCR) is 20% higher in the Alfred Wegener Institute Climate Model (AWI‐CM) compared to the Max Planck Institute Earth System Model (MPI‐ESM) whereas the equilibrium climate sensitivity (ECS) is by up to 10% higher in AWI‐CM. These results are largely independent of the two considered model resolutions for each model. The two coupled CMIP6 models share the same atmosphere‐land component ECHAM6.3 developed at the Max Planck Institute for Meteorology (MPI‐M). However, ECHAM6.3 is coupled to two different ocean models, namely the MPIOM sea ice‐ocean model developed at MPI‐M and the FESOM sea ice‐ocean model developed at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). A reason for the different TCR is related to ocean heat uptake in response to greenhouse gas forcing. Specifically, AWI‐CM simulations show stronger surface heating than MPI‐ESM simulations while the latter accumulate more heat in the deeper ocean. The vertically integrated ocean heat content is increasing slower in AWI‐CM model configurations compared to MPI‐ESM model configurations in the high latitudes. Weaker vertical mixing in AWI‐CM model configurations compared to MPI‐ESM model configurations seems to be key for these differences. The strongest difference in vertical ocean mixing occurs inside the Weddell and Ross Gyres and the northern North Atlantic. Over the North Atlantic, these differences materialize in a lack of a warming hole in AWI‐CM model configurations and the presence of a warming hole in MPI‐ESM model configurations. All these differences occur largely independent of the considered model resolutions.
    Beschreibung: Plain Language Summary: The transient climate response (TCR) describes how strongly near‐surface temperatures warm in response to gradually increasing greenhouse‐gas levels. Here we investigate the role of the ocean which takes up heat and thereby delays the surface warming. Two models of the Coupled Model Intercomparison Project Phase 6 (CMIP6), the Alfred Wegener Institute Climate Model (AWI‐CM) and the Max Planck Institute Earth System Model (MPI‐ESM), which use the same atmosphere model but different ocean models are selected for this study. In AWI‐CM the upper ocean layers heat faster than in MPI‐ESM, while the opposite is true for the deep ocean. As a consequence, the TCR is 20% stronger in AWI‐CM compared to MPI‐ESM. We find that weaker vertical ocean mixing in AWI‐CM compared to MPI‐ESM, especially over the northern North Atlantic and the Weddell and Ross Gyres, is key for these differences. Our findings corroborate the importance of realistic ocean mixing in climate models when it comes to getting the strength and timing of climate change right.
    Beschreibung: Key Points: The transient climate response in two coupled models with the same atmosphere but different ocean components differs by 20%. The upper (deeper) ocean heats faster (slower) in AWI‐CM compared to MPI‐ESM, independent of model resolution. Vertical mixing in the northern North Atlantic and the Weddell and Ross Gyres appears to be key for these differences.
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: German Climate Computing Centre (DKRZ)
    Beschreibung: Federal Ministry of Education and Research of Germany
    Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Beschreibung: https://esgf-data.dkrz.de/projects/cmip6-dkrz/
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Publikationsdatum: 2022-04-01
    Beschreibung: We report results from geoarchaeological investigations at Cuncaicha rock shelter (4480 m above sea level) in the high Andes of southern Peru. Using field observations, geomorphological, micromorphological, micro‐Fourier transform infrared spectroscopy, Bayesian modeling of radiocarbon ages, and archaeological data, we analyzed the entire stratigraphic sequence to determine depositional and postdepositional processes and agents to assess the impact of bioturbation and to correlate the deposits with regional paleoenvironmental information. The archaeological record is represented well on a microscale, and bioturbation has not destroyed the stratigraphic integrity. The Terminal Pleistocene sediments that contain the oldest archaeological material at the site, dating to ~12.3–11.1 ka, are especially well preserved and capped by a layer of tufa. Depositional changes from autochthonous carbonate precipitation during the Terminal Pleistocene toward allochthonous aeolian sedimentation in the Early Holocene reflect changing environmental and climatic conditions. Formation of a soil during the Late‐Middle Holocene caused postdepositional alterations and likely correlates to variable environmental conditions. We use these results to formulate a site formation model for Cuncaicha rock shelter that integrates archaeological, chronological, and paleoenvironmental data.
    Beschreibung: Deutsche Forschungsgemeinschaft, Germany http://dx.doi.org/10.13039/501100001659
    Beschreibung: National Science Foundation, United States
    Schlagwort(e): ddc:551.447 ; ddc:558
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Publikationsdatum: 2022-04-01
    Beschreibung: The interaction between the land surface and the atmosphere is a crucial driver of atmospheric processes. Soil moisture and precipitation are key components in this feedback. Both variables are intertwined in a cycle, that is, the soil moisture – precipitation feedback for which involved processes and interactions are still discussed. In this study the soil moisture – precipitation feedback is compared for the sempiternal humid Ammer catchment in Southern Germany and for the semiarid to subhumid Sissili catchment in West Africa during the warm season, using precipitation datasets from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), from the German Weather Service (REGNIE) and simulation datasets from the Weather Research and Forecasting (WRF) model and the hydrologically enhanced WRF‐Hydro model. WRF and WRF‐Hydro differ by their representation of terrestrial water flow. With this setup we want to investigate the strength, sign and variables involved in the soil moisture – precipitation feedback for these two regions. The normalized model spread between the two simulation results shows linkages between precipitation variability and diagnostic variables surface fluxes, moisture flux convergence above the surface and convective available potential energy in both study regions. The soil moisture – precipitation feedback is evaluated with a classification of soil moisture spatial heterogeneity based on the strength of the soil moisture gradients. This allows us to assess the impact of soil moisture anomalies on surface fluxes, moisture flux convergence, convective available potential energy and precipitation. In both regions the amount of precipitation generally increases with soil moisture spatial heterogeneity. For the Ammer region the soil moisture – precipitation feedback has a weak negative sign with more rain near drier patches while it has a positive signal for the Sissili region with more rain over wetter patches. At least for the observed moderate soil moisture values and the spatial scale of the Ammer region, the spatial variability of soil moisture is more important for surface‐atmosphere interactions than the actual soil moisture content. Overall, we found that soil moisture heterogeneity can greatly affect the soil moisture – precipitation feedback.
    Beschreibung: WRF and WRF‐hydro model simulations are used to determine the sign and analyse the mechanisms of the soil moisture ‐ precipitation feedback for the sempiternal humid Ammer catchment in Southern Germany and for the semiarid to subhumid Sissili catchment in West Africa during the warm season. The generation of moist convection is favoured over surfaces with moderately high soil moisture gradients in the Ammer region, while for the Sissili region the location of precipitation tends to be related to areas with high soil moisture gradients. For the Ammer region the soil moisture – precipitation feedback has a weak negative sign with more rain near drier patches while it has a positive signal for the Sissili region with more rain over wetter patches.
    Beschreibung: Untersuchung des Klimas des südlichen Afrikas – ein Brückenschlag vom frühen Holozän bis heute
    Beschreibung: Transregional Collaborative Research Center
    Schlagwort(e): ddc:551.57 ; ddc:631.4
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Publikationsdatum: 2022-04-01
    Beschreibung: In the hyperarid Atacama Desert in northern Chile, rare precipitation events can leave long‐lasting geomorphological traces and have strong impacts on biota. While moisture conveyor belts (MCBs) and atmospheric rivers (ARs) have been associated with extreme precipitation in semiarid regions, their role for the Atacama Desert has not been previously investigated. This study reveals that about four MCBs per year make landfall in the Atacama Desert. According to simulated precipitation, 40–80% of the total precipitation between the coast and the Andean foothills is associated with MCBs. A case study reveals an elevated moisture transport decoupled from the maritime boundary layer, which is generalized by a composite analysis. Back trajectories reveal the Amazon Basin as the main source of moisture. MCB landfall times are derived from the AR catalog by Guan and Waliser (2015), https://doi.org/10.1002/2015jd024257. Implications of the results on paleoclimate reconstructions are discussed.
    Beschreibung: Plain Language Summary: In the extremely dry Atacama Desert in northern Chile, rare rain events can trigger landscape alterations and have strong impacts on various life forms. Traces of such events are conserved within the desert soil over long time periods throughout the enduring dryness. Such traces constitute climate archives, which can be excavated and explored. Understanding particular conditions, which lead to extreme precipitation events is necessary to interpret such archives, reconstruct climate history, and explore thresholds of life at the dry limit. In this study, the role of a weather phenomenon called moisture conveyor belt (MCB) is quantified for the first time for the Atacama Desert. It is demonstrated that depending on region, 40–80% of the total rainfall is associated with these phenomena. In contrast to atmospheric river characteristics reported for midlatitudes, a unique vertical structure with an elevated moisture transport independent of the near‐surface layer is discovered here. Even though the identified MCBs approach the Atacama Desert from northwesterly directions across the Pacific Ocean, the associated moisture mostly originates from the Amazon Basin.
    Beschreibung: Key Points: For most parts of the Atacama Desert, more than half of the total precipitation is related to moisture conveyor belts (MCBs). In contrast to midlatitudes, main moisture transport takes place in mid‐tropospheric layers decoupled from the maritime boundary layer. The main origin of the MCB‐related moisture is found to be the Amazon Basin.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://www.crc1211db.uni-koeln.de/search/view.php?dataID=38
    Beschreibung: http://www.cr2.cl/datos-de-precipitacion/
    Beschreibung: http://explorador.cr2.cl/
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Publikationsdatum: 2022-04-01
    Beschreibung: The analysis of concentration‐discharge (C‐Q) relationships from low‐frequency observations is commonly used to assess solute sources, mobilization, and reactive transport processes at the catchment scale. High‐frequency concentration measurements are increasingly available and offer additional insights into event‐scale export dynamics. However, only few studies have integrated inter‐annual and event‐scale C‐Q relationships. Here, we analyze high‐frequency measurements of specific conductance (EC), nitrate (NO3‐N) concentrations and spectral absorbance at 254 nm (SAC254, as a proxy for dissolved organic carbon) over a two year period for four neighboring catchments in Germany ranging from more pristine forested to agriculturally managed settings. We apply an integrated method that adds a hysteresis term to the established power law C‐Q model so that concentration intercept, C‐Q slope and hysteresis can be characterized simultaneously. We found that inter‐event variability in C‐Q hysteresis and slope were most pronounced for SAC254 in all catchments and for NO3‐N in forested catchments. SAC254 and NO3‐N event responses in the smallest forested catchment were closely coupled and explainable by antecedent conditions that hint to a common near‐stream source. In contrast, the event‐scale C‐Q patterns of EC in all catchments and of NO3‐N in the agricultural catchment without buffer zones around streams were less variable and similar to the inter‐annual C‐Q relationship indicating a homogeneity of mobilization processes over time. Event‐scale C‐Q analysis thus added key insights into catchment functioning whenever the inter‐annual C‐Q relationship contrasted with event‐scale responses. Analyzing long‐term and event‐scale behavior in one coherent framework helps to disentangle these scattered C‐Q patterns.
    Beschreibung: Key Points: We compare event‐scale and inter‐annual concentration‐discharge relationships in four adjoined catchments with contrasting land use. The variability of event‐scale C‐Q relationships was shaped by land use and antecedent conditions for biogeochemically reactive but not for geogenic solutes. For biogeochemically reactive solutes, event‐scale C‐Q patterns can contrast the inter‐annual pattern obtained from all observations.
    Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    Publikationsdatum: 2022-04-01
    Beschreibung: It has long been proposed that during Pleistocene climatic perturbations the Balkan peninsula sustained refugial areas for fauna, flora, and potentially, hominins. In this study, we explore Middle Palaeolithic subsistence at the peninsula's southern end, Greece, and discuss how the evidence contributes to our understanding of the region's character as a refugium. We present new data from the recent reanalysis of the fauna from Asprochaliko rockshelter and the ongoing zooarchaeological investigations at Lakonis Cave 1 and compare them with published analyses from Klissoura Cave 1. We employ taxonomic abundance and diversity indices, as well as mortality profiles, to investigate hominin prey choice. Additional taphonomic observations provide further information on carcass exploitation. We examine changes in the faunal composition of the three sites in an attempt to identify the extent to which climate might have influenced resource availability and diversity in the region, stimulating resource intensification or diversification processes. Our results suggest that Middle Palaeolithic hominins consistently acquired high‐ranked prey through time. However, interregional differences in resource exploitation indicate that local topography and microclimate mediated prey choice and availability.
    Beschreibung: Institute for Aegean Prehistory http://dx.doi.org/10.13039/100001182
    Beschreibung: Senckenberg Gesellschaft für Naturforschung
    Schlagwort(e): ddc:560
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Publikationsdatum: 2022-04-01
    Beschreibung: We present a workflow to estimate geostatistical aquifer parameters from pumping test data using the Python package welltestpy. The procedure of pumping test analysis is exemplified for two data sets from the Horkheimer Insel site and from the Lauswiesen site, Germany. The analysis is based on a semi‐analytical drawdown solution from the upscaling approach Radial Coarse Graining, which enables to infer log‐transmissivity variance and horizontal correlation length, beside mean transmissivity, and storativity, from pumping test data. We estimate these parameters of aquifer heterogeneity from type‐curve analysis and determine their sensitivity. This procedure, implemented in welltestpy, is a template for analyzing any pumping test. It goes beyond the possibilities of standard methods, for example, based on Theis' equation, which are limited to mean transmissivity and storativity. A sensitivity study showed the impact of observation well positions on the parameter estimation quality. The insights of this study help to optimize future test setups for geostatistical aquifer analysis and provides guidance for investigating pumping tests with regard to aquifer statistics using the open‐source software package welltestpy.
    Beschreibung: Article impact statement: We present a workflow to infer parameters of subsurface heterogeneity from pumping test data exemplified at two sites using welltestpy.
    Beschreibung: German Federal Environmental Foundation (DBU) http://dx.doi.org/10.13039/100007636
    Schlagwort(e): ddc:551.49
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Publikationsdatum: 2022-04-01
    Beschreibung: The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here, we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in the southern South China Sea: the Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters. We used a set of variables derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter and four mesozooplankton size fractions to identify changes in the nitrogen source and TP of mesozooplankton across these habitats. We found clear indications of a shift in N sources for biological production from nitrate in near‐coastal waters with shallow mixed layer depths toward an increase in diazotroph‐N inputs in oceanic waters with deep mixed layer depths where diazotrophs shaped the phytoplankton community. The N source shift was accompanied by a lengthening of the food chain (increase in the TP). This may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ15N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, a high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels.
    Beschreibung: Plain Language Summary: Zooplankton are one of the central pillars of the marine food web and form an important link between the production of organic matter by phytoplankton and biomass at higher trophic levels (e.g., fish). Of particular interest are mesozooplankton (0.2–20 mm in size), which encompass a diverse assemblage of animals utilizing a range of feeding strategies, including herbivory, omnivory, and carnivory. Since mass and energy are lost with each trophic step, their prevailing feeding strategy determines the availability of mass and energy to the upper food web. The exact relationship between carnivores and herbivores in mesozooplankton has so far only been studied with complex experiments or in homogenous environments. We have now resolved zooplankton feeding relationships in a highly dynamic marine environment. Specifically, we used stable nitrogen isotopes in amino acids and bulk organic matter in combination with a habitat‐delineating method for phytoplankton to directly determine the ratio of carnivores to herbivores in zooplankton from dynamic habitats in the South China Sea. The mass and energy transfer across trophic levels is less efficient in such variable marine environments compared to stable open ocean systems. These findings represent a big step toward understanding the dynamics of planktonic food webs in general.
    Beschreibung: Key Points: Trophic structure of mesozooplankton is regulated by similar environmental factors such as phytoplankton assemblages. Diazotrophy and nutrient availability correlated with enhanced mesozooplankton carnivory in a complex tropical marine ecosystem. Mass and energy transfer across trophic levels of planktonic food webs are less efficient in spatially and temporally variable ecosystems.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: National Foundation for Science and Technology Development (NAFOSTED) http://dx.doi.org/10.13039/100007224
    Beschreibung: National Aeronautics and Space Administration (NASA) http://dx.doi.org/10.13039/100000104
    Beschreibung: Schmidt Ocean Institute
    Beschreibung: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Beschreibung: https://doi.org/10.5061/dryad.bk3j9kdbv
    Schlagwort(e): ddc:577.7
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Publikationsdatum: 2022-04-01
    Beschreibung: Increased deposition of fine sediments in rivers and streams affects a range of key ecosystem processes across the sediment–water interface, and it is a critical aspect of river habitat degradation and restoration. Understanding the mechanisms leading to fine sediment accumulation along and across streambeds and their effect on ecological processes is essential for comprehending human impacts on river ecosystems and informing river restoration. Here, we introduce the HydroEcoSedimentary tool (HEST) as an integrated approach to assess hydro‐sedimentary and ecologically relevant processes together. The HEST integrates the estimation of sedimentary processes in the interstitial zone, as well as hydraulic, geochemical and ecological assessments, with a focus on brown trout early life stages. Compared to other methods, the HEST expands the possibilities to monitor and quantify fine sediment deposition in streambeds by differentiating between vertical, lateral and longitudinal infiltration pathways, and distinguishing between the depth (upper vs. lower layers) at which interstitial processes occur within the sediment column. By testing the method in two rivers with different degrees of morphological degradation, we detail the possible measurements and uses of the HEST, demonstrate its feasibility and discuss its reliability.
    Beschreibung: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Beschreibung: Bavarian State Ministry of Science and Arts (Bayerisches Staatsministerium für Wissenschaft und Kunst)
    Schlagwort(e): ddc:551.48 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Publikationsdatum: 2022-04-01
    Beschreibung: In thermally stratified reservoirs, inflows form density currents according to the interplay between inflow temperature and reservoir stratification. The temperature of inflowing water is affected by catchment properties, including shading by riparian vegetation. We hypothesize that the degree of shading in the catchment can affect the inflow dynamics in downstream reservoirs by changing inflow temperature and consequently the nature of the density current. We test it for a subtropical drinking water reservoir by combining catchment‐scale hydrological and stream temperature modeling with observations of reservoir stratification. We analyze the formation of density currents, defined as under, inter and overflow, for scenarios with contrasting shading conditions in the catchment. Inflow temperatures were simulated with the distributed water‐balance model LARSIM‐WT, which integrates heat‐balance and water temperature. River temperature measurements and simulations are in good agreement with a RMSE of 0.58°C. In simulations using the present state of shading, underflows are the most frequent flow path, 63% of the annual period. During the remaining time, river intrusion form interflows. In a scenario without stream shading, average inflow temperature increased by 2.2°C. Thus, interflows were the most frequent flow path (51%), followed by underflows (34%) and overflows (15%). With this change, we would expect a degradation of reservoir water quality, as overflows promote longer periods of anoxia and nutrient loads would be delivered to the photic zone, a potential trigger for algae blooms. This study revealed a potentially important, yet unexplored aspect of catchment management for controlling reservoir water quality.
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Beschreibung: https://doi.org/10.5281/zenodo.4746288
    Schlagwort(e): ddc:628.1 ; ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 50
    Publikationsdatum: 2022-04-01
    Beschreibung: Water isotope ratios of ice cores are a key source of information on past temperatures. Through fractionation within the hydrological cycle, temperature is imprinted in the water isotopic composition of snowfalls. However, this signal of climatic interest is modified after deposition when snow remains at the surface exposed to the atmosphere. Comparing time series of surface snow isotopic composition at Dome C with satellite observations of surface snow metamorphism, we found that long summer periods without precipitation favor surface snow metamorphism altering the surface snow isotopic composition. Using excess parameters (combining D,17O, and 18O fractions) allow the identification of this alteration caused by sublimation and condensation of surface hoar. The combined measurement of all three isotopic compositions could help identifying ice core sections influenced by snow metamorphism in sites with very low snow accumulation.
    Beschreibung: Plain Language Summary: Water isotopes in ice core records are often used to reconstruct past climate temperature variations. Classically, the temperature signal is thought to be imprinted in water isotopes of precipitation, and then archived in the ice core as it falls, and in cold areas of Antarctica, piles up for very long period. Here, we show that the surface snow isotopic composition varies in between precipitation events, suggesting that there might be more than one contribution to the isotopic signal in ice core records. This is particularly important for low accumulation sites, where the snow at the surface remains exposed for very long time periods. The combined use of several isotopic ratios in surface snow helps us disentangle the processes that create this signal.
    Beschreibung: Key Points: During summer without precipitation, intense snow metamorphism shows a strong water isotopic signature. During summer without precipitation, intense snow metamorphism shows a strong water isotopic signature. The d‐excess and 17O‐excess of the snow is a proxy of snow metamorphism for low accumulation regions.
    Beschreibung: FP7 Ideas: European Research Council (FP7 Ideas) http://dx.doi.org/10.13039/100011199
    Beschreibung: Foundation Prince Albert of Monaco
    Beschreibung: Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156
    Beschreibung: DFG project CLIMAIC
    Beschreibung: https://doi.pangaea.de/10.1594/PANGAEA.934273
    Schlagwort(e): ddc:551.31 ; ddc:551.9
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 51
    Publikationsdatum: 2022-04-01
    Beschreibung: Large artificial lakes and reservoirs affect the meteorological regime of the shore area and the local climate takes on a number of new features that were previously absent. This work focuses on the weather impact of the Alqueva reservoir, the largest artificial lake in Western Europe. An extensive set of numerical simulations using Meso‐NH mesoscale atmospheric model coupled with FLake (Freshwater Lake) scheme was carried out. The simulations covered a 12‐month period that was chosen to compose a so‐called Typical Meteorological Year. This artificial time period is meant to represent the typical meteorological conditions in the region and the model results are used to assess the changes in the local climate. To evaluate the raw impact of the reservoir, two different scenarios of simulations were compared: (A) with the reservoir as it exists nowadays and (B) without the reservoir using the older surface dataset. The results show decrease of air temperature during daytime (10–9°C) and nighttime increase (up to 10°C). In nearest towns, daily maximum temperature decreased and daily minimum temperature increased, which refers to milder weather conditions. Alqueva mainly showed suppression in fog formation in the nearby area. Local breeze regime was studied and monthly lake/land breezes were described.
    Beschreibung: Large lakes and artificial reservoirs can affect the meteorological regime of their coastal areas and impact the local climate. This work focuses on the weather impact of the Alqueva reservoir, the largest artificial lake in Western Europe, studied on the basis of mesoscale atmospheric modelling data over the 12‐month period composed in a typical meteorological year for the region of interest.
    Beschreibung: ALOP project
    Beschreibung: COMPETE 2020 ICT project
    Beschreibung: Fundação para a Ciência e a Tecnologia http://dx.doi.org/10.13039/501100001871
    Beschreibung: TOMAQAPA
    Beschreibung: http://mesonh.aero.obs-mip.fr/mesonh54/Download
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Publikationsdatum: 2022-04-01
    Beschreibung: In light of global warming and rising relative sea level (RSL), detailed reconstructions of RSL histories and their controlling processes are essential in order to manage coastal‐protection challenges. This study contributes to unravelling Holocene RSL change on the East Frisian North Sea coast in high resolution and with a new approach for the German Bight. For the first time, a transfer function (vertical error: 29.7 cm ≙ ~11% of the mean tidal range) for RSL change based on a combined training set of benthic foraminifers and ostracods from the back‐barrier tidal basin of Spiekeroog is applied to the Holocene record of the back‐barrier tidal basin of Norderney. The resulting RSL curve for the Norderney tidal basin is corrected for decompaction and shows a deceleration in RSL rise between 6000 and 5000 cal bp. The smallest possible error envelope (~1 m) results from the good suitability of salt‐marsh layers between 5000 and 4000 cal bp. The RSL curve provides an approach towards the closure of the common data gap of peat‐based curves for the southern North Sea related to a lack of basal peats in the youngest age range, and verifies regional differences in glacial isostatic adjustment.
    Beschreibung: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Beschreibung: Niedersächsisches Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/501100010570
    Schlagwort(e): ddc:551.468
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Publikationsdatum: 2022-04-01
    Beschreibung: Light is a fundamental resource for phytoplankton. To utilize the available light, most phytoplankton species possess pigments in taxon‐specific combinations and quantities, which in turn result in a specific use of certain wavelengths. This optimizes the light use efficiency, allows for a complementary use of light, and may be an additional driver for community structure. While the effects of light intensity on phytoplankton biomass production and community composition have been intensively studied, here we focused on the effects of specific light spectrum quality (thus light color) on a natural phytoplankton community. In a controlled mesocosm experiment we reduced the supplied wavelength range to its blue, green, or red part of the light spectrum and compared the responses of each treatment to a full spectrum control over 28 d. Highest community growth rates were observed under blue, lowest under red light. Light absorption by the communities showed adaptation toward the supplied wavelength range. Community composition was significantly affected by light quality treatments, driven by Bacillariophyta and Chlorophyta, whereas pigment composition was not. Furthermore, lower species richness but higher evenness occurred when communities were exposed to red light compared to the full spectrum. We expected the response of phytoplankton communities to changes in the light spectrum to be driven by a combination of species sorting and pigment acclimation; however, the effect of species sorting turned out to be stronger. Our study showed that, even if species might acclimate, changes in the available light spectrum affect primary production and phytoplankton community composition.
    Schlagwort(e): ddc:579
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Publikationsdatum: 2022-04-01
    Beschreibung: Climate warming and management will likely affect carbon (C) fluxes of montane grassland ecosystems. In this study, we assessed the effect of simultaneous warming (+2°C) and decreased precipitation (−25%) on carbon exchange of montane grasslands in S‐Germany by translocating large intact plant‐soil cores from a high altitude to a low altitude site. Cores received two common grassland management regimes: intensive (4–5 cuts and slurry application) and extensive (1–2 cuts and slurry application). Diurnal patterns of net ecosystem exchange (NEE) and total ecosystem respiration (Reco) were measured over 1.5 years in 2–3 weeks intervals during the snow free period. Additional data on environmental controls, that is, photosynthetic active radiation, grass height and soil moisture and temperature, were used to develop empirical models to estimate daily and annual fluxes of gross primary production (GPP) and Reco. Considering the 2 years period (2014 and 2015), we found that, under warmer and slightly drier conditions, both GPP and Reco significantly (p 〈 0.01) increased (up to 20%) but with a higher temperature sensitivity of Reco, particularly in intensive managed grassland. The higher temperature sensitivity of Reco reduced the NEE by 0.7 t C ha−1 yr−1 for both extensive and intensive management, respectively. Considering additional carbon inputs via slurry and exports via harvest (i.e., annual net ecosystem carbon budget), our results showed that managed grasslands are already a source of C under current climate conditions (1.7–1.8 t ha−1 yr−1) which significantly (p 〈 0.05) increased under climate warming (2.3–2.9 t ha−1 yr−1).
    Beschreibung: Key Points: Climate change can accelerate depletion of montane grassland C stocks. Under warmer conditions gross primary production and ecosystem respiration (Reco) increase, but Reco with a higher temperature sensitivity. Adaptation of grassland cutting and manure management regimes can likely reduce ecosystem carbon losses.
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: Deutscher Akademischer Austauschdienst (DAAD) http://dx.doi.org/10.13039/501100001655
    Beschreibung: Office of China Postdoc Council
    Beschreibung: Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156
    Beschreibung: https://figshare.com/articles/dataset/Data%5Fof%5Fpublication%5FWang%5Fet%5Fal%5Funder%5Freview%5FGBC/14566215
    Schlagwort(e): ddc:630 ; ddc:577.22
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    Publikationsdatum: 2022-04-01
    Beschreibung: We present a Lagrangian framework for identifying mechanisms that control the isotopic composition of mid‐tropospheric water vapor in the Sahel region during the West African Monsoon 2016. In this region mixing between contrasting air masses, strong convective activity, as well as surface and rain evaporation lead to high variability in the distribution of stable water isotopologues. Using backward trajectories based on high‐resolution isotope‐enabled model data, we obtain information not only about the source regions of Sahelian air masses, but also about the evolution of H2O and its isotopologue HDO (expressed as δD) along the pathways of individual air parcels. We sort the full trajectory ensemble into groups with similar transport pathways and hydro‐meteorological properties, such as precipitation and relative humidity, and investigate the evolution of the corresponding paired {H2O, δD} distributions. The use of idealized process curves in the {H2O, δD} phase space allows us to attribute isotopic changes to contributions from (a) air mass mixing, (b) Rayleigh condensation during convection, and (c) microphysical processes depleting the vapor beyond the Rayleigh prediction, i.e., partial rain evaporation in unsaturated and isotopic equilibration in saturated conditions. Different combinations of these processes along the trajectory ensembles are found to determine the final isotopic composition in the Sahelian troposphere during the monsoon. The presented Lagrangian framework is a powerful tool for interpreting tropospheric water vapor distributions. In the future, it will be applied to satellite observations of {H2O, δD} over Africa and other regions in order to better quantify characteristics of the hydrological cycle.
    Beschreibung: Key Points: New Lagrangian framework to attribute variability in {H2O, δD} distributions to air mass mixing and phase changes of water. Application to West African Monsoon season 2016 shows characteristic mixing and precipitation effects along trajectories. New framework can be used for the interpretation of satellite and in‐situ observations, and for model validation in future work.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: Swiss National Science Foundation
    Beschreibung: European Space Agency
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: Ministerium für Wissenschaft, Forschung und Kunst Baden‐Württemberg (MWK) http://dx.doi.org/10.13039/501100003542
    Schlagwort(e): ddc:551.5
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    Publikationsdatum: 2022-04-01
    Beschreibung: Porto Selvaggio in southern Italy is where the Uluzzian culture was first identified and documented, providing key insights into the transition from the Middle to the Upper Paleolithic. The area has also yielded evidence for continuous occupations by Neanderthals spanning between Marine Isotope Stage (MIS) 5 and 3. Situated in the Natural Regional Park of Porto Selvaggio, different sites were excavated by Borzatti von Löwenstern in the 1960 and 1970s. As one of the initiatives in the research program of the Museo della Preistoria di Nardò, we have revisited the artifact assemblages from these caves. Based on the lithic analysis of production sequences, we document the development of Levallois and laminar methods before MIS 3 when this form of reduction sequence presumably dominated in the region according to the previous research. The review of the lithic assemblages is combined with the contextualization of chronostratigraphy and paleoenvironmental study in the region to consider the possible role that this region had for Neanderthals during unfavorable climatic conditions.
    Beschreibung: Nomos – Servizi per la Cultura del Patrimonio
    Beschreibung: Ente di Gestione del Parco Naturale Regionale di Portoselvaggio e Palude del Capitano
    Beschreibung: Municipality of Nardò
    Schlagwort(e): ddc:569.986 ; ddc:551.447
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    Publikationsdatum: 2022-04-01
    Beschreibung: Observations by the Magnetospheric Multiscale spacecraft (MMS) of an unusual layer, located between the dayside magnetosheath and the magnetosphere, alternating with encounters with the magnetosheath during an extended time period between December 31, 2015 and January 01, 2016, when the interplanetary magnetic field was strongly southward and the Earth's dipole tilt large and negative, are presented. It appears to have been magnetically connected to both magnetosphere and magnetosheath. The layer appears to be located mostly on closed field lines and was bounded by a rotational discontinuity (RD) at its magnetosheath edge and by the magnetosphere on its earthward side. A separatrix layer, with heated magnetosheath electrons streaming unidirectionally along the field lines, was present sunward of the RD. We infer that the layer was started by a dominant reconnection site well north of the spacecraft and that it may have gained additional width, from a large drop in solar wind density and ram pressure, which preceded the beginning of the event by more than an hour. Relative to the magnetosheath, in which the magnetic field was strongly southward, this unusual layer was characterized by a less southward, more dawnward magnetic field of lower magnitude. The plasma density and flow speed in the region were lower than in the magnetosheath, albeit with Alfvénic jetting occurring at the magnetosheath edge as well as at the magnetospheric edge of the layer. The closing of the magnetic field lines requires the existence of another reconnection site, located southward/tailward of MMS.
    Beschreibung: Key Points: Magnetopause encounter for strongly southward interplanetary magnetic field, low solar wind Alfvén Mach number, and large dipole tilt. Persistent and broad magnetopause layer with magnetospheric O+ and heated magnetosheath plasma. Inferred dominant reconnection site near northern cusp, far from the Magnetospheric Multiscale spacecraft location.
    Beschreibung: MPE
    Beschreibung: NASA http://dx.doi.org/10.13039/100000104
    Beschreibung: Norwegian Research Council http://dx.doi.org/10.13039/501100005416
    Schlagwort(e): ddc:538.7
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 58
    Publikationsdatum: 2022-04-01
    Beschreibung: In designed experiments, different sources of variability and an adequate scale of measurement need to be considered, but not all approaches in common usage are equally valid. In order to elucidate the importance of sources of variability and choice of scale, we conducted an experiment where the effects of biochar and slurry applications on soil properties related to soil fertility were studied for different designs: (a) for a field‐scale sampling design with either a model soil (without natural variability) as an internal control or with composited soils, (b) for a design with a focus on amendment variabilities, and (c) for three individual field‐scale designs with true field replication and a combined analysis representative of the population of loess‐derived soils. Three silty loam sites in Germany were sampled and the soil macroaggregates were crushed. For each design, six treatments (0, 0.15 and 0.30 g slurry‐N kg−1 with and without 30 g biochar kg−1) were applied before incubating the units under constant soil moisture conditions for 78 days. CO2 fluxes were monitored and soils were analysed for macroaggregate yields and associated organic carbon (C). Mixed‐effects models were used to describe the effects. For all soil properties, results for the loess sites differed with respect to significant contributions of fixed effects for at least one site, suggesting the need for a general inclusion of different sites. Analysis using a multilevel model allowed generalizations for loess soils to be made and showed that site:slurry:biochar and site:slurry interactions were not negligible for macroaggregate yields. The use of a model soil as an internal control enabled observation of variabilities other than those related to soils or amendments. Experiments incorporating natural variability in soils or amendments resulted in partially different outcomes, indicating the need to include all important sources of variability. Highlights Effects of biochar and slurry applications were studied for different designs and mixed‐effects models were used to describe the effects. Including an internal control allowed observation of, e.g., methodological and analytical variabilities. The results suggested the need for a general inclusion of different sites. Analysis using a multilevel model allowed generalizations for loess soils. The results indicated the need to include all important sources of variability.
    Schlagwort(e): ddc:631.4
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Publikationsdatum: 2022-04-01
    Beschreibung: The radiocarbon signature of respired CO2 (∆14C‐CO2) measured in laboratory soil incubations integrates contributions from soil carbon pools with a wide range of ages, making it a powerful model constraint. Incubating archived soils enriched by “bomb‐C” from mid‐20th century nuclear weapons testing would be even more powerful as it would enable us to trace this pulse over time. However, air‐drying and subsequent rewetting of archived soils, as well as storage duration, may alter the relative contribution to respiration from soil carbon pools with different cycling rates. We designed three experiments to assess air‐drying and rewetting effects on ∆14C‐CO2 with constant storage duration (Experiment 1), without storage (Experiment 2), and with variable storage duration (Experiment 3). We found that air‐drying and rewetting led to small but significant (α 〈 0.05) shifts in ∆14C‐CO2 relative to undried controls in all experiments, with grassland soils responding more strongly than forest soils. Storage duration (4–14 y) did not have a substantial effect. Mean differences (95% CIs) for experiments 1, 2, and 3 were: 23.3‰ (±6.6), 19.6‰ (±10.3), and 29.3‰ (±29.1) for grassland soils, versus −11.6‰ (±4.1), 12.7‰ (±8.5), and −24.2‰ (±13.2) for forest soils. Our results indicate that air‐drying and rewetting soils mobilizes a slightly older pool of carbon that would otherwise be inaccessible to microbes, an effect that persists throughout the incubation. However, as the bias in ∆14C‐CO2 from air‐drying and rewetting is small, measuring ∆14C‐CO2 in incubations of archived soils appears to be a promising technique for constraining soil carbon models.
    Beschreibung: Plain Language Summary: Soils play a key role in the global carbon cycle by sequestering carbon from the atmosphere for decades to millennia. However, it is unclear if they will continue to do so as the climate changes. Microbial decomposition of soil organic matter returns carbon back to the atmosphere, and radiocarbon dating of this returning CO2 (∆14C‐CO2) can be used to quantify how long carbon is stored in ecosystems. Incubating archived soils could provide unique insight into soil carbon sequestration potential by quantifying the change in ∆14C‐CO2 over time. However, air‐drying, duration of archiving, and subsequent rewetting of soils may bias estimates of sequestration potential by altering the balance of younger versus older carbon leaving the soil. We compared ∆14C‐CO2 from soils incubated with and without air‐drying and archiving, and found that the air‐dried soils appeared to release slightly older carbon than soils that had never been air‐dried. The amount of time the soils were archived did not have an effect. Since the bias from air‐drying and rewetting was small, incubating archived soils appears to be a promising technique for improving our ability to model soil carbon cycling under global climate change.
    Beschreibung: Key Points: ∆14C of CO2 measured in incubations of archived soils provides additional constraints for soil carbon models. Air‐drying and rewetting soils shifted the ∆14C of respired CO2 by 10‰–20‰ independent of the duration of storage. Differences in direction and magnitude of ∆14C‐CO2 shifts between forests and grasslands depended on sampling year and system C dynamics.
    Beschreibung: EC, H2020, H2020 Priority Excellent Science, H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Beschreibung: https://doi.org/10.5281/zenodo.4959705
    Schlagwort(e): ddc:551.9 ; ddc:631.41 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 60
    Publikationsdatum: 2022-04-01
    Beschreibung: Temperate forest soils are often considered as an important sink for atmospheric carbon (C), thereby buffering anthropogenic CO2 emissions. However, the effect of tree species composition on the magnitude of this sink is unclear. We resampled a tree species common garden experiment (six sites) a decade after initial sampling to evaluate whether forest floor (FF) and topsoil organic carbon (Corg) and total nitrogen (Nt) stocks changed in dependence of tree species (Norway spruce—Picea abies L., European beech—Fagus sylvatica L., pedunculate oak—Quercus robur L., sycamore maple—Acer pseudoplatanus L., European ash—Fraxinus excelsior L. and small‐leaved lime—Tilia cordata L.). Two groups of species were identified in terms of Corg and Nt distribution: (1) Spruce with high Corg and Nt stocks in the FF developed as a mor humus layer which tended to have smaller Corg and Nt stocks and a wider Corg:Nt ratio in the mineral topsoil, and (2) the broadleaved species, of which ash and maple distinguished most clearly from spruce by very low Corg and Nt stocks in the FF developed as mull humus layer, had greater Corg and Nt stocks, and narrow Corg:Nt ratios in the mineral topsoil. Over 11 years, FF Corg and Nt stocks increased most under spruce, while small decreases in bulk mineral soil (esp. in 0–15 cm and 0–30 cm depth) Corg and Nt stocks dominated irrespective of species. Observed decadal changes were associated with site‐related and tree species‐mediated soil properties in a way that hinted towards short‐term accumulation and mineralisation dynamics of easily available organic substances. We found no indication for Corg stabilisation. However, results indicated increasing Nt stabilisation with increasing biomass of burrowing earthworms, which were highest under ash, lime and maple and lowest under spruce. Highlights We studied if tree species differences in topsoil Corg and Nt stocks substantiate after a decade. The study is unique in its repeated soil sampling in a multisite common garden experiment. Forest floors increased under spruce, but topsoil stocks decreased irrespective of species. Changes were of short‐term nature. Nitrogen was most stable under arbuscular mycorrhizal species.
    Beschreibung: Deutsche Forschungsgemeinschaff (DFG)
    Schlagwort(e): ddc:551.9 ; ddc:631.41
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Publikationsdatum: 2022-04-01
    Beschreibung: Porosity is one of the key properties of fluvial sediments. It is defined as the ratio of pore volume to total volume. In river science, porosity is often assumed to be spatially constant, which might be a gross simplification of reality. Ignoring the spatial variations in porosity can cause errors in morphological, ecological, hydrological, hydrogeological and sedimentological applications. Although detailed information about spatial porosity variations can be obtained from porosity measurements at field sites, such information has never been collected where these variations might be important. In this study, field porosity measurements were carried out to quantify the magnitude of the spatial porosity variation for four different sedimentological environments of a braided river: a confluence, a tributary delta, a braid bar and a secondary channel. A nuclear density gauge was used for the measurement of porosity. The nuclear density gauge proved to be a time‐saving and labour‐saving technique that produces accurate porosity values with a root mean square error of 0.03. The four sedimentological environments showed significant differences in porosity, with mean porosity being lower for confluence and bar than for delta and secondary channel. Semi‐variogram analysis showed the absence of any spatial correlation in porosity for distances beyond 4 m. This shows that distance cannot be used as a parameter for porosity extrapolation in a fluvial system unless the extrapolation distance is less than 4 m. At least eight measurements of porosity are required to obtain a reliable estimate of mean porosity in a sedimentary environment, i.e. with uncertainty 〈0.03. Although grain size characteristics were found to have a significant impact on porosity, the relationships between these parameters and porosity were not very strong in this study. The unique porosity dataset, presented in this article, provides a valuable source of information for researchers and river managers.
    Beschreibung: Deutsche Forschungsgemeinschaft
    Schlagwort(e): ddc:550
    Sprache: Englisch
    Materialart: doc-type:article
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  • 62
    Publikationsdatum: 2022-04-05
    Beschreibung: Contaminant analysis in biota extracts can be hampered by matrix interferences caused by, for example, co‐extracted lipids that compromise the quality of the analytical data and require frequent maintenance of the analytical instruments. In the present study, using gas chromatography coupled to high resolution mass spectrometry (GC‐HRMS), we aimed to develop and validate a straightforward, robust, and reproducible cleanup method with acceptable recoveries for diverse compound classes with a wide range of physicochemical properties representative of pollutant screening in biota extracts. We compared Oasis PRiME HLB cartridges, Agilent Captiva EMR‐Lipid cartridges, and “Freeze‐Out” with salmon lipids spiked with 113 target chemicals. The EMR‐Lipid cartridges provided extracts with low matrix effects at reproducible recoveries of the multi‐class target analytes (93 ± 9% and 95 ± 7% for low and high lipid amounts, respectively). The EMR‐Lipid cartridges were further tested with spiked pork lipids submitted to total extraction or silicone‐based passive sampling. Reproducible recoveries were achieved and matrix residuals were largely removed as demonstrated gravimetrically for both types of extracts. Ion suppression of halogenated compounds was not as efficiently removed by the cleanup of total and silicone‐based extracts of pork lipids as for the salmon lipids. However, the samples with clean up provided better instrument robustness than those without cleanup. Hence, EMR‐Lipid cartridges were shown to be efficient as a cleanup method in multi‐class monitoring of biota samples and open up new possibilities as a suitable cleanup method for silicone extracts in biota passive sampling studies using GC‐HRMS analysis. Environ Toxicol Chem 2021;40:2693–2704. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Beschreibung: H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Schlagwort(e): ddc:577.14
    Sprache: Englisch
    Materialart: doc-type:article
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  • 63
    Publikationsdatum: 2022-04-05
    Beschreibung: Human alteration of nutrient cycles has caused persistent and widespread degradation of water quality around the globe. In many regions, including Western Europe, elevated nitrate (NO3−) concentration in surface waters contributes to eutrophication and noncompliance with environmental legislation. Discharge, NO3− concentrations and the vulnerability of the aquatic ecosystems to eutrophication often exhibit a distinct seasonality. Understanding spatial patterns and long‐term trends in this seasonality is crucial to improve water quality management. Here, we hypothesized that NO3− concentrations during high‐flow periods would respond faster to changes in nutrient inputs than low‐flow concentrations because of greater connectivity of shallow diffuse NO3− sources with the river network. To test this hypothesis, we compiled long‐term NO3− and discharge time series from 290 Western European catchments. To characterize the long‐term trajectories of seasonal NO3− concentration, we propose a novel hysteresis approach comparing low‐ and high‐flow NO3− concentration in the context of multi‐decadal N input changes. We found synchronous winter maxima of NO3− and discharge in 84% of the study catchments. However, contrary to our hypothesis, there were surprisingly diverse long‐term trajectories of seasonal NO3− concentration. Both clockwise (faster high‐flow NO3− response) and counterclockwise hysteresis (faster low‐flow NO3− response) occurred in similar proportions, potentially due to a high complexity in the underlying processes. Spatial variability of seasonality in NO3− concentration across the catchments was more pronounced and better predictable than its long‐term variability. This work demonstrates the value of seasonal and inter‐annual hydrochemical analysis and provides new tools for water quality monitoring and management.
    Beschreibung: Plain Language Summary: Nitrogen is an essential element of all living organisms and has thus often been used excessively as fertilizer to secure food production. However, surface waters can suffer from elevated nutrients inputs, causing toxic algal blooms and impairing drinking water quality, especially during summer low flows. To manage water quality, it is crucial to understand these seasonal variations of nitrogen and discharge and the underlying processes. We used data from 290 catchments in France and Germany to characterize average seasonality patterns and their long‐term evolution across the variety of landscapes and human influences. This allowed classifying catchment behavior and linking them to controls. As expected, both nitrogen and discharge peak during winter in most catchments (84%). However, there are well explainable deviations, for example, in mountainous regions. The long‐term evolution of seasonality was more diverse than expected suggesting a complex interplay of various processes with the long input history from fertilization and wastewater being part of the controls. We found that the differences among catchments were greater than the long‐term changes of seasonality within most catchments. By identifying catchment typologies, our study increases the understanding of nitrate seasonality patterns across a large extent and thus supports ecological water quality management.
    Beschreibung: Key Points: Spatial patterns of nitrate and discharge seasonality are linked to topography and hydroclimate with winter maxima dominating for both. After decreasing nutrient inputs, cases with decreases in river nitrate preceding during low‐ and high‐flow seasons occurred equally often. Spatial variability of nitrate seasonality is greater and more predictable from catchment characteristics than its long‐term variability.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Beschreibung: US National Science Foundation (NSF)
    Schlagwort(e): ddc:551
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Publikationsdatum: 2022-04-05
    Beschreibung: About 91,300 ha of peatlands has been rewetted in western Europe since the mid‐1990s. Still, it is unknown how long‐term rewetting alters the dissolved organic matter (DOM) concentration, molecular composition, and functional groups. We examined these DOM characteristics in three peatland types subjected to 47‐ to 231‐yr drainage and 18‐ to 24‐yr rewetting to address this knowledge gap. Cold water‐extractable DOM was characterized by pyrolysis field ionization mass spectrometry (Py‐FIMS) and X‐ray absorption near‐edge structure (XANES) spectroscopy. The dissolved organic carbon (DOC) concentration in the rewetted forest peatland was 2.7 times higher than in the drained forest peatland. However, rewetting decreased the DOC concentrations by 1.5 and 4 times in the coastal peatland and percolation mire, respectively, compared with their respective drained peatlands at the topsoil horizons. The Py‐FIMS analysis revealed that all nine DOM compound classes' relative abundances differed between the rewetted and drained forest peatland with the lower relative abundances of the labile DOM compound classes in the rewetted forest peatlands. However, most DOM compound classes' relative abundances were similar between the rewetted and drained coastal peatlands and percolation mires. The XANES also revealed nine carbon and seven nitrogen functional groups with no apparent differences between the two contrasting management practices. The influence of drainage and rewetting on DOC concentration and molecular composition depends on peatland type, drainage period, rewetting intensity, and peat degradation status that should be considered in future research for understanding DOM transformation and transportation from degraded and restored peatland ecosystems.
    Beschreibung: Core Ideas: Dissolved organic matter (DOM) concentrations and molecular compositions depend on degradation status in drained peatlands. Rewetting effects on DOM concentrations and molecular compositions differ with peatland types. Pyrolysis field ionization mass spectrometry reveals management effects on DOM molecular compositions compared with X‐ray absorption near‐edge structure.
    Schlagwort(e): ddc:577.687
    Sprache: Englisch
    Materialart: doc-type:article
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  • 65
    Publikationsdatum: 2022-04-05
    Beschreibung: Nitrate monitoring is commonly conducted with low‐spatial resolution, only at the outlet or at a small number of selected locations. As a result, the information about spatial variations in nitrate export and its drivers is scarce. In this study, we present results of high‐spatial resolution monitoring conducted between 2012 and 2017 in 65 sub‐catchments in an Alpine mesoscale river catchment characterized by a land‐use gradient. We combined stable isotope techniques with Bayesian mixing models and geostatistical methods to investigate nitrate export and its main drivers, namely, microbial N turnover processes, land use and hydrological conditions. In the investigated sub‐catchments, mean values of NO3− concentrations and its isotope signatures (δ15NNO3 and δ18ONO3) varied from 2.6 to 26.7 mg L−1, from −1.3‰ to 13.1‰, and from −0.4‰ to 10.1‰, respectively. In this study, land use was an important driver for nitrate export. Very strong and strong positive correlations were found between percentages of agricultural land cover and δ15NNO3, and NO3− concentration, respectively. Mean proportional contributions of NO3− sources varied spatially and seasonally, and followed land‐use patterns. The mean contribution of manure and sewage was much higher in the catchments characterized by a high percentage of agricultural and urban land cover comparing to forested sub‐catchments. Specific NO3− loads were strongly correlated with specific discharge and moderately correlated with NO3− concentrations. The nitrate isotope and concentration analysis results suggest that nitrate from external sources is stored and accumulated in soil storage pools. Nitrification of reduced nitrogen species in those pools plays the most important role for the N‐dynamics in the Erlauf river catchment. Consequently, nitrification of reduced N sources was the main nitrate source except for a number of sub‐catchments dominated by agricultural land use. In the Erlauf catchment, denitrification plays only a minor role in controlling NO3− export on a regional scale.
    Beschreibung: We integrated results of the BMM with informative priors and top‐kriging. Reduced N stored in soil is an important source for stream N in a mesoscale catchment. Manure and sewage is the main NO3− source in agricultural sub‐catchments. Denitrification played only a minor role in controlling regional scale NO3− export.
    Schlagwort(e): ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
    Publikationsdatum: 2022-04-05
    Beschreibung: Recently, the potent antiandrogen 4‐methyl‐7‐diethylaminocoumarin (C47) and its potential transformation products 4‐methyl‐7‐ethylaminocoumarin (C47T1) and 4‐methyl‐7‐aminocoumarin (C47T2) were identified as novel environmental contaminants. We assessed for the first time the sources, distribution, and fate of these compounds in aquatic systems using the Holtemme River (Saxony‐Anhalt, Germany), which is a hotspot for these contaminants. To this end, wastewater‐treatment plant (WWTP) influent and effluent samples, surface water samples over 3 years, and the longitudinal profiles in water, sediment, and gammarids were analyzed. From the longitudinal profile of the river stretch, the WWTP of Silstedt was identified as the sole point source for these compounds in the River Holtemme, and exposure concentrations in the low micrograms per liter range could be recorded continuously over 3 years. Analysis of WWTP influent and effluent showed a transformation of approximately half of the C47 into C47T1 and C47T2 but no complete removal. A further attenuation of the three coumarins after discharge into the river could be largely attributed to dilution, while transformation was only approximately 20%, thus suggesting a significant persistence in aquatic systems. Experimentally derived partitioning coefficients between water and sediment organic carbon exceeded those predicted using the OPERA quantitative structure–activity relationship tools and polyparameter linear free‐energy relationships by up to 93‐fold, suggesting cation binding as a significant factor for their sorption behavior. Near‐equilibrium conditions between water and sediment were not observed close to the emitting WWTP but farther downstream in the river. Experimental and predicted bioaccumulation factors for gammarids were closely matching, and the concentrations in field‐sampled gammarids were close to steady state with exposure concentrations in the water phase of the river. Environ Toxicol Chem 2021;40:3078–3091. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Beschreibung: Helmholtz‐Gemeinschaft http://dx.doi.org/10.13039/501100001656
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): ddc:577.614
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    facet.materialart.
    Unbekannt
    https://atlas.netto-null.org
    In:  EPIC3https://atlas.netto-null.org, https://atlas.netto-null.org
    Publikationsdatum: 2022-04-06
    Beschreibung: Salt marshes, along with seagrass and mangroves, are known to be globally important carbon sinks. Salt marsh plants absorb CO2 from the air. Through photosynthesis, they use the carbon to build plant parts such as leaves and roots, i.e. organic biomass. Salt marsh plants produce a considerable amount of belowground biomass. This organic matter is persistent and only decays over a long period of time. Over time, some of the carbon-containing biomass is permanently buried in the marsh soil. Here, conditions are usually favourable for the preservation of the organic material, which can lead to carbon storage for thousands of years. In this way, salt marshes absorb CO2 from the air and store it as organic carbon in the soil - a mechanism that removes CO2 from the atmosphere and counteracts climate change. In addition, salt marshes act as a filter and trap for sediment and organic material that enters the salt marsh from outside. When water levels are high, salt marshes are flooded and the salt marsh plants literally fish out sediment and organic material from the water above them. Organic material in particular also contains carbon, which is then deposited in the salt marsh and later stored in the soil. The accumulation of carbon from sources outside the salt marsh also contributes to the role of salt marshes as carbon sinks.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Miscellaneous , notRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    facet.materialart.
    Unbekannt
    In:  EPIC3
    Publikationsdatum: 2022-04-06
    Beschreibung: Just like salt marshes and mangroves, seagrasses are ecologically important habitats in coastal ecosystems and are also important carbon storages. Seagrasses absorb CO2 and other forms of inorganic carbon from water and air and produce organic biomass, i.e. new plant components, by means of photosynthesis. Dead parts of the seagrass plant can be buried into the deeper, oxygen-poor layers of the tidal flat sediment by current-induced sediment reallocation or burrowing activity of animals. Bacteria that are responsible for decomposing the organic material and would thus release the carbon again can hardly become active there due to the lack of oxygen. The carbon incorporated in the plant parts can thus be stored in the seabed for many centuries. In addition to this internal source, seagrasses also act as filters for sediment and organic material, which is transported into the seagrass bed from outside. Sediment and organic material may originate from deeper areas of the sea and then be transported towards the coast, or may be directly from nearby coastal vegetation. Above a seagrass bed, these components are literally fished out of the seawater near the bottom as if with a comb. In this way, new layers of sediment and organic material are continuously deposited in the seagrass meadow, leading to a further accumulation of organic material that can be stored in the seabed for up to thousands of years.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Miscellaneous , notRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 69
    facet.materialart.
    Unbekannt
    In:  EPIC315th International Scientific Wadden Sea Symposium, 30 Nov 2021 - 02 Dec 2021, Online.
    Publikationsdatum: 2022-04-06
    Beschreibung: The introduction of non-indigenous species may cause strong effects on biodiversity, species interactions and functioning of native soft-bottom coastal ecosystems. Especially introduced bioengineering organisms modify existing benthic habitat structures and thereby habitat-specific species interactions. In the Wadden Sea, beds of native blue mussels have been invaded by Pacific oysters Magalana gigas, which caused a large-scale shift from pure epibenthic Mytilus edulis beds to current mixed reefs of mussels and oysters. These newly developed biotic habitats may affect the occurrence of former associated key organisms and their ecological functions. In this context, we studied the grazing activity of native periwinkles Littorina littorea and the spatial distribution of M. edulis in oyster reefs in the northern Wadden Sea and explored the resulting distribution patterns of barnacle epibionts attached to oyster and mussel shells. A manipulative field experiment revealed that density of L. littorea significantly affects the recruitment success of barnacles Semibalanus balanoides on oyster shells. The highest number of barnacles recruited at periwinkle exclusion and this relationship was already known for pure blue mussel beds in the past. Barnacle epigrowth on blue mussel shells, however, changed with the new position of mussels within the oyster matrix and is nowadays lower than in former times. Our results demonstrate that introduced bioengineering organisms may alter, native biotic habitats but associated species interactions may remain the same. Additionally, it shows that native species may profit from the new structures by, for example, being less overgrown with detrimental barnacle overgrowth.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Conference , notRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 70
    facet.materialart.
    Unbekannt
    In:  EPIC3ECSA 58 - EMECS 13, 06 Sep 2021 - 09 Sep 2021, online.
    Publikationsdatum: 2022-04-06
    Beschreibung: The introduction of non-indigenous species may cause strong effects on biodiversity, species interactions and functioning of native coastal ecosystems. Especially introduced bioengineering organisms may fundamentally change native soft-bottom ecosystems by modifying existing benthic habitat structures and thereby habitat-specific species interactions. The introduction of Pacific oysters Crassostrea gigas into the sedimentary coastal area of the south-eastern North Sea and its preferred settlement on native blue mussel shells caused a large-scale shift from pure epibenthic Mytilus edulis beds to current mixed reefs of mussels and oysters. To investigate whether the newly developed biotic habitat affects the occurrence of associated key organisms and their ecological functions, we studied the long-term occurrence of periwinkles Littorina littorea and their grazing activity on barnacles attached to Pacific oyster shells in the northern Wadden Sea. We found no negative effects of oyster density increase on periwinkle population dynamics in the last two decades, which spans a time-period from the beginning of Pacific oyster establishment on mussel beds to oyster dominance today. A manipulative field experiment revealed that density of L. littorea significantly affects the recruitment success of barnacles Semibalanus balanoides on oyster shells. The highest number of barnacle recruited at periwinkle exclusion. Thus, snail density and resulting grazing activity may control barnacle overgrowth on oyster shells, which is known to cause detrimental effects on overgrown bivalves. The company of introduced oysters and native periwinkles in the Wadden Sea shows that alien species may find native friends in newly conquered ecosystems with mutual benefits.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Conference , notRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Publikationsdatum: 2022-04-06
    Beschreibung: The automatic generation of travel‐time maps is a prerequisite for many fields of application such as tourist assistance and spatial decision support systems, for example to analyze the accessibility of health and social facilities. The task is to determine outlines of zones that are reachable from a user’s location in a given amount of time. In this work we focus on travel‐time maps with a formally guaranteed SEPARATION PROPERTY in the sense that a zone exactly contains the part of the road network that is reachable within a pre‐defined time from a given starting point and start time. In contrast to other automated methods that create travel‐time maps, our approach generates schematized travel‐time maps that reduce the visual complexity by representing each zone by an octilinear polygon, that is, the edges of the polygons use only eight pre‐defined orientations. We aim for octilinear polygons with a small number of bends to further optimize the legibility of the map. The reachable parts of the road network are determined by the integration of timetable information for different modes of public transportation, for example buses, trains or ferries, and pedestrian walkways based on a multimodal time‐expanded network. Moreover, the travel‐time maps generated visualize multiple travel times using a map overlay of different time zones and taking natural barriers such as rivers into account. In experiments on real‐world data we compare our schematic visualizations to travel‐time maps created with other visualization techniques with respect to simple but robust quality measures such as the number of bends and the perimeter of the zones.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:526.0285 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
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  • 72
    Publikationsdatum: 2022-04-06
    Beschreibung: Small headwater streams are recognized for intense outgassing to the atmosphere of climate‐relevant carbon dioxide (CO2) and methane (CH4). Though these headwaters are markedly oversaturated for both CO2 and CH4, the origins and controls over the fate of these two carbon‐gases are still poorly constrained, especially for the stronger greenhouse gas CH4. Here, by measuring stream‐based production of CO2 and CH4, concurrently with their rates of outgassing to the atmosphere, we identify distinct biophysical control mechanisms for each gas. We show that while CO2 is largely imported from the catchment in proportion to discharge, CO2 outgassing can be modulated by in‐stream metabolism to offset outgassing by up to 30% in spring and summer. In contrast, CH4 shows a non‐linear response to seasonal changes in discharge and is predominantly produced in the streambed in relation to sediment type. Further, once released from the streambed, outgassing of CH4 at the surface and flow‐driven dilution occur far more rapidly than biological methane oxidation and CH4 leaves the water largely unaltered by biology. Incorporating the intense carbon cycling of headwater streams into the global carbon cycle will require distinct parameterizations for each carbon gas in Earth system models.
    Beschreibung: Plain Language Summary: There is growing interest in the global carbon cycle and how carbon is transformed in the landscape into the greenhouse gases carbon dioxide (CO2) and methane–with methane being by far the more potent than CO2. Streams and rivers are recognized hotspots of carbon cycling in the landscape, commonly harboring large amounts of CO2 and methane–yet what controls either gas in streams is not fully understood. Without that understanding, we cannot predict how carbon cycling will respond to climate change or to other human alteration of the landscape. Here we researched different components of the carbon cycle in streams to show that each gas is influenced by quite distinct “biophysical” control mechanisms. While CO2 in streams results largely from physical run‐off from the land, once in a stream it can be changed by the stream biology that ebbs and flows with the seasons. Contrastingly, methane is largely created by biology within the streambed itself but once released into the wider stream that methane is then dispersed by the physical forces of stream flow. Put more simply, CO2 is physically carried to the stream to then be altered by biology, whereas as methane is borne from biology in the stream, to then be physically carried away.
    Beschreibung: Key Points: There are different controls on the outgassing of the greenhouse gases carbon dioxide and methane in streams. Carbon dioxide results largely from physical run‐off from the land and is then altered in stream by biology depending on season. In contrast, methane is created in the streambed but once released to the stream is then dispersed by the physical forces of stream flow.
    Beschreibung: Natural Environment Research Council (NERC) http://dx.doi.org/10.13039/501100000270
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: EC | H2020 | H2020 Priority Excellent Science | H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Beschreibung: FNU
    Beschreibung: Danish National Research Foundation
    Schlagwort(e): ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    Publikationsdatum: 2022-03-30
    Beschreibung: Carbonate‐associated sulfate (CAS) is an important proxy for reconstructing marine sulfur cycling throughout Earth's history. In order to assess the impact of carbonate neomorphism on δ34SCAS data, a mineralogical‐spatial transect from early diagenetic limestone into low‐temperature hydrothermal dolostone was analyzed in the middle Triassic Latemar platform interior, northern Italy. This study addresses the yet unconstrained question whether hydrothermal dolostone preserves a marine δ34SCAS signature and, hence, might represent an archive for past seawater sulfate. In this study, δ34SCAS values were measured in low‐temperature hydrothermal dolostone and compared with data from their corresponding precursor limestone. Results shown here reveal that δ34SCAS values for dolostone and precursor limestone are indistinguishable. This points to a rock‐buffered middle Triassic marine δ34S signature not affected by hydrothermal alteration. Hence, hydrothermal dolostone represents, under favorable conditions, an archive for unraveling past marine sulfur cycling.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:551.9 ; ddc:552
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 74
    Publikationsdatum: 2022-03-30
    Beschreibung: Chondrules are thought to play a crucial role in planet formation, but the mechanisms leading to their formation are still a matter of unresolved discussion. So far, experiments designed to understand chondrule formation conditions have been carried out only under the influence of terrestrial gravity. In order to introduce more realistic conditions, we developed a chondrule formation experiment, which was carried out at long‐term microgravity aboard the International Space Station. In this experiment, freely levitating forsterite (Mg2SiO4) dust particles were exposed to electric arc discharges, thus simulating chondrule formation via nebular lightning. The arc discharges were able to melt single dust particles completely, which then crystallized with very high cooling rates of 〉105 K h−1. The crystals in the spherules show a crystallographic preferred orientation of the [010] axes perpendicular to the spherule surface, similar to the preferred orientation observed in some natural chondrules. This microstructure is probably the result of crystallization under microgravity conditions. Furthermore, the spherules interacted with the surrounding gas during crystallization. We show that this type of experiment is able to form spherules, which show some similarities with the morphology of chondrules despite very short heating pulses and high cooling rates.
    Beschreibung: Carl Zeiss Meditec AG http://dx.doi.org/10.13039/501100002806
    Beschreibung: BIOVIA Science Ambassador program
    Beschreibung: Bundesministerium für Wirtschaft und Energie http://dx.doi.org/10.13039/501100006360
    Beschreibung: Deutsches Zentrum für Luft‐ und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Beschreibung: NanoRacks LLC
    Beschreibung: DreamUp
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: Dr. Rolf M. Schwiete Stiftung
    Schlagwort(e): ddc:549 ; ddc:550.78
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 75
    Publikationsdatum: 2022-03-30
    Beschreibung: In this study, the variability of the spectral dispersion of droplet size distributions (DSDs) in convective clouds is investigated. Analyses are based on aircraft measurements of growing cumuli near the Amazon basin, and on numerical simulations of an idealized ice‐free cumulus. In cleaner clouds, the relative dispersion ϵ, defined as the ratio of the standard deviation to the mean value of the droplet diameter, is negatively correlated with the ratio of the cloud water content (qc) to the adiabatic liquid water content (qa), while no strong correlation between ϵ and qc/qa is seen in polluted clouds. Bin microphysics numerical simulations suggest that these contrasting behaviors are associated with the effect of collision‐coalescence in cleaner clouds, and secondary droplet activation in polluted clouds, in addition to the turbulent mixing of parcels that experienced different paths within the cloud. Collision‐coalescence simultaneously broadens the DSDs and decreases qc, explaining the inverse relationship between ϵ and qc/qa in cleaner clouds. Secondary droplet activation broadens the DSDs but has little direct impact on qc. The combination of a rather modest DSD broadening due to weak collision‐coalescence with enhanced droplet activation in both diluted and highly undiluted cloud regions may contribute to maintain a relatively uniform ϵ within polluted clouds. These findings can be useful for parameterizing the shape parameter (μ) of gamma DSDs in bulk microphysics cloud‐resolving models. It is shown that emulating the observed μ−qc/qa relationship improves the estimation of the collision‐coalescence rate in bulk microphysics simulations compared to the bin simulations.
    Beschreibung: Key Points: Droplet size distribution patterns observed in warm cumuli reflect the roles of collision‐coalescence, secondary activation, and mixing. The intra‐cloud distribution of droplet spectral dispersion varies with aerosol loading. Emulating the observed shape‐parameter improves bulk estimations of collision‐coalescence in models.
    Beschreibung: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) http://dx.doi.org/10.13039/501100001807
    Beschreibung: Max Planck Society (MPG)
    Beschreibung: U.S. Department of Energy (DOE) http://dx.doi.org/10.13039/100000015
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: HALO
    Schlagwort(e): ddc:551.5
    Sprache: Englisch
    Materialart: doc-type:article
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  • 76
    Publikationsdatum: 2022-03-30
    Beschreibung: The estimation of crustal structure and thickness is essential in understanding the formation and evolution of terrestrial planets. Initial planetary missions with seismic instrumentation on board face the additional challenge of dealing with seismic activity levels that are only poorly constrained a priori. For example, the lack of plate tectonics on Mars leads to low seismicity, which could, in turn, hinder the application of many terrestrial data analysis techniques. Here we propose using a joint inversion of receiver functions and apparent incidence angles, which contain information on absolute S‐wave velocities of the subsurface. Since receiver function inversions suffer from a velocity depth trade‐off, we in addition exploit a simple relation that defines apparent S‐wave velocity as a function of observed apparent P‐wave incidence angles to constrain the parameter space. We then use the Neighborhood Algorithm for the inversion of a suitable joint objective function. The resulting ensemble of models is then used to derive uncertainty estimates for each model parameter. In preparation for the analysis of data from the InSight mission, we show the application of our proposed method on Mars synthetics and sparse terrestrial data sets from different geological settings using both single and multiple events. We use information‐theoretic statistical tests as model selection criteria and discuss their relevance and implications in a seismological framework.
    Beschreibung: Key Points: We propose the joint inversion of receiver functions and apparent S‐wave velocity curves to estimate crustal thickness. Using the Neighborhood Algorithm, we show how a full uncertainty estimate can be computed from an ensemble solution. The method is applied to Martian synthetics and terrestrial data sets comprising single and multiple events.
    Beschreibung: IMPRS
    Beschreibung: Emeritus group
    Beschreibung: DLR German Space Agency
    Beschreibung: http://www.orfeus-eu.org/data/eida/
    Beschreibung: http://instaseis.ethz.ch/marssynthetics/
    Schlagwort(e): ddc:622.1592 ; ddc:523
    Sprache: Englisch
    Materialart: doc-type:article
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  • 77
    Publikationsdatum: 2022-03-30
    Beschreibung: Complex networks of both natural and engineered flow paths control the hydrology of streams in major cities through spatio‐temporal variations in connection and disconnection of diverse water sources. We used spatially extensive and temporally intensive sampling of water stable isotopes to disentangle the hydrological sources of the heavily urbanized Panke catchment (~220 km2) in the north of Berlin, Germany. The isotopic data enabled us to partition stream water sources across the catchment using a Bayesian mixing analysis. The upper part of the catchment streamflow is dominated by groundwater (~75%) from gravel aquifers. In dry summer periods, streamflow becomes intermittent in the upper catchment, possibly as a result of local groundwater abstractions. Storm drainage dominates the responses to precipitation events. Although such events can dramatically change the isotopic composition of the upper stream network, storm drainage only accounts for 10%–15% of annual streamflow. Moving downstream, subtle changes in sources and isotope signatures occur as catchment characteristics vary and the stream is affected by different tributaries. However, effluents from a wastewater treatment plant (WWTP), serving 700,000 people, dominate stream flow in the lower catchment (~90% of annual runoff) where urbanization effects are more dramatic. The associated increase in sealed surfaces downstream also reduces the relative contribution of groundwater to streamflow. The volume and isotopic composition of storm runoff is again dominated by urban drainage, though in the lower catchment, still only about 10% of annual runoff comes from storm drains. The study shows the potential of stable water isotopes as inexpensive tracers in urban catchments that can provide a more integrated understanding of the complex hydrology of major cities. This offers an important evidence base for guiding the plans to develop and re‐develop urban catchments to protect, restore, and enhance their ecological and amenity value.
    Beschreibung: Intermittent urban stream. Groundwater and waste water dominance. High temporal and spatial stable isotope dataset. End member mixing analysis. Water import.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Beschreibung: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Schlagwort(e): ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
    Publikationsdatum: 2022-03-30
    Beschreibung: The widening and narrowing of river‐valley aquifers can cause valley‐scale lateral hyporheic exchange even if the river is straight and its slope is uniform. For the aforementioned system, we derive a semi‐analytical solution describing steady‐state groundwater flow for a simplified two‐dimensional geometry of the aquifer and uniform lateral influx from hillslopes. We use this solution to evaluate the geometry‐driven lateral hyporheic exchange flux between the aquifer and the river. By systematically varying the model parameters, we decipher how this flux and the area of the exchange zone depend on geometric (e.g., minimum and maximum domain width) and hydrogeological parameters (e.g., hydraulic conductivity, ambient hydraulic gradient and lateral influxes). The results suggest pronounced hyporheic flow for cases with distinct widening behavior and small cross‐sectional widths at the floodplain inlet and outlet. Furthermore, we analyze the travel‐time distribution of water flowing through the exchange zone, which approximately follows a beta distribution. We express our findings in terms of simple proxy‐equations that can be used to easily estimate the exchange flux, the area of the exchange zone, and the associated travel‐time distribution for a given geographic/landscape setting.
    Beschreibung: Key Points: We develop a semi‐analytical solution describing lateral exchange between rivers and floodplain aquifers driven by the valley geometry. We investigate how the exchange flux, the area of the hyporheic zone, and travel times depend on geometric and hydraulic properties. We derive simplified expressions allowing estimating these quantities as a preliminary step prior to detailed site investigations.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://osf.io/fykr9/
    Beschreibung: https://jonasallgeier.github.io/fpsimple
    Schlagwort(e): ddc:551.48
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    Publikationsdatum: 2022-03-30
    Beschreibung: Abstract The number of newly discovered and confirmed impact structures on earth is growing continuously. In this review paper, the main attributes of 198 confirmed impact structures and 10 further structures, for which final confirmation based on the identification of shock features is not yet entirely satisfying, are presented. The impact craters are compared statistically, with regard to their morphology, structure, and status of erosion or burial. The size– and age–frequency distributions of terrestrial impact structures are presented. Additional aspects concern target petrography and shock effects found in the craters. Based on the discovery statistics of presently known crater structures, an estimate can be made of the number of craters that await discovery. The paper is complementary to the recently published atlas of terrestrial impact structures by Gottwald et al. (2020).
    Schlagwort(e): ddc:551
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    Publikationsdatum: 2022-03-30
    Beschreibung: The prevailing view suggests that the Eemian interglacial on the European Plain was characterized by largely negligible geomorphic activity beyond the coastal areas. However, systematic geomorphological studies are sparse. Here we present a detailed reconstruction of Eemian to Early Weichselian landscape evolution in the vicinity of a small fingerlake on the northern margin of the Salzwedel Palaeolake in Lower Saxony (Germany). We apply a combination of seismics, sediment coring, pollen analysis and luminescence dating on a complex sequence of colluvial, paludal and lacustrine sediments. Results suggest two pronounced phases of geomorphic activity, directly before the onset and at the end of the Eemian period, with an intermediate period of pronounced landscape stability. The dynamic phases were largely driven by incomplete vegetation cover, but likely accentuated by fluvial incision in the neighbouring Elbe Valley. Furthermore, we discovered Neanderthal occupation at the lakeshore during Eemian pollen zone (PZ) E IV, which is chronologically in line with other known Eemian sites of central Europe. Our highly‐resolved spatio‐temporal data substantially contribute to the understanding of climate‐induced geomorphic processes throughout and directly after the last interglacial period. It helps unraveling the landscape dynamics between the coastal areas to the north and the loess belt to the south.
    Beschreibung: Two phases of channel incision at the Saalian‐Eemian transition and in the late Eemian. Incisions closely followed by rising water tables. Long‐lasting phase of geomorphic stability in the mid‐Eemian, characterized by: very dense forest cover. the formation of a fingerlake within the paleochannel with gradually sinking water table. no influx of clastic sediments, but deposition of peat and lake‐marl deposits.
    Beschreibung: Max‐Planck‐Gesellschaft http://dx.doi.org/10.13039/501100004189
    Schlagwort(e): ddc:554.3 ; ddc:551
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    Publikationsdatum: 2022-03-30
    Beschreibung: The bed of estuaries is often characterized by ripples and dunes of varying size. Whereas smaller bedforms adapt their morphological shape to the oscillating tidal currents, large compound dunes (here: asymmetric tidal dunes) remain stable for periods longer than a tidal cycle. Bedforms constitute a form roughness, that is, hydraulic flow resistance, which has a large‐scale effect on tidal asymmetry and, hence, on hydrodynamics, sediment transport, and morphodynamics of estuaries and coastal seas. Flow separation behind the dune crest and recirculation on the steep downstream side result in turbulence and energy loss. Since the energy dissipation can be related to the dune lee slope angle, asymmetric dune shapes induce variable flow resistance during ebb and flood phases. Here, a noncalibrated numerical model has been applied to analyze the large‐scale effect of symmetric and asymmetric dune shapes on estuarine tidal asymmetry evaluated by residual bed load sediment transport at the Weser estuary, Germany. Scenario simulations were performed with parameterized bed roughness of symmetric and asymmetric dune shapes and without dune roughness. The spatiotemporal interaction of distinct dune shapes with the main drivers of estuarine sediment and morphodynamics, that is, river discharge and tidal energy, is shown to be complex but substantial. The contrasting effects of flood‐ and ebb‐oriented asymmetric dunes on residual bed load transport rates and directions are estimated to be of a similar importance as the controls of seasonal changes of discharge on these net sediment fluxes at the Lower Weser estuary. This corroborates the need to consider dune‐induced directional bed roughness in numerical models of estuarine and tidal environments.
    Beschreibung: Estuarine tidal asymmetry is found to depend on directional dune‐induced flow resistance interacting on spatiotemporal scales with the combined influence of fluvial discharge and tidal forcing. The nonequilibrium nature of asymmetric dunes in tidal flow is critical to large‐scale hydrodynamics and bed load sediment fluxes and needs to be addressed through inter‐tidal‐phase variable bedform roughness in numerical models of tidal environments.
    Beschreibung: Federal Waterways Engineering and Research Institute (BAW), Hamburg, Germany
    Beschreibung: Kiel Marine Science (KMS)
    Beschreibung: German Research Foundation (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:551.36 ; ddc:550.724
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    facet.materialart.
    Unbekannt
    John Wiley & Sons, Ltd | Chichester, UK
    Publikationsdatum: 2022-03-30
    Beschreibung: With increasing resolution of numerical weather prediction (NWP) models, classical subgrid‐scale processes become increasingly resolved on the model grid. In particular, turbulence in the planetary boundary layer (PBL) is vertically already partially resolved in contemporary models. For classical local PBL schemes, resulting up‐gradient heat transports cannot be treated correctly. Thus, nonlocal turbulence schemes have been developed in the past. As the horizontal grid sizes of NWP models become smaller than a few kilometers, the large turbulence eddies in the PBL will also start to become partially resolved in the horizontal direction. A very flexible way to formulate nonlocal turbulent exchange is the transilient matrix method, which is used here to develop a new turbulence parameterization. The resulting NLT3D scheme applies transilient mixing matrices to subgrid‐scale transports in all three dimensions. We compare results of WRF real‐case simulations including our scheme, a classical local turbulence scheme (MYNN), and an existing nonlocal one‐dimensional scheme (ACM2) with observations from field campaigns over homogeneous terrain (CASES‐99) and complex terrain (CAPTEX). Over homogeneous terrain, all three schemes similarly well capture the observed surface fluxes and radiosonde profiles, whereas over complex terrain more differences become obvious. During a tracer release experiment (CAPTEX) over the Appalachian mountain region, the mixing and vertical extent of the PBL turn out to be decisive to reproduce the observed advection speed of the tracer‐marked air mass. Deeper mixing not only accelerates surface winds but also enables tracer to travel faster at higher altitudes and then mix back to the ground. As results from a version of NLT3D with only standard horizontal Smagorinsky diffusion (NLT1D) demonstrate, simulating three‐dimensional turbulence can be beneficial already at horizontal grid sizes of a few kilometers.
    Beschreibung: Decreasing grid sizes in numerical weather prediction models demand the inclusion of nonlocal effects and horizontal turbulence in turbulence parameterizations. This is the motivation for the development of the nonlocal three‐dimensional turbulence (NLT3D) scheme. Vertical nonlocal mixing accelerates the horizontal transport of near‐surface tracers by fast advection at higher altitudes (see figure), and horizontal turbulence enhances tracer dispersion. As validated by observations, both effects are beneficial to the forecast quality already at grid sizes of a few kilometers.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 83
    Publikationsdatum: 2022-03-30
    Beschreibung: Landslides are a major hazard in mountainous regions, represent a threat to human life, and cause substantial economic costs. While some landslide hazard assessments, including hazards maps, are available for Germany, their spatial coverage is not uniform. In the Black Forest, several landslides have recently attracted public attention, but the landslide hazard in this region has received limited consideration in literature to date. This study focuses on the spatial pattern and size distribution of soil‐borne landslides in the submountainous valley of Menzenschwand. A combination of remote sensing, geophysical surveying, and geotechnical testing was used to map and characterize the landslide inventory of two selected hillslopes. In the statistical analyses, we observe a larger proportion of small‐scale landslides with size below 100 m2 than usually reported in similar studies. This effect may be related to the low cohesion of the soil (glacial deposits). As a major result, a cutoff in the distribution at large landslide sizes compared with the expected power‐law tail of the distribution was found. While the maximum landslide size found in this study was about 1100 m2, the largest landslide should theoretically be at least 2500 m2 at 95% probability. The cutoff at large sizes is probably due to the limited soil thickness, where about 50% of the considered area has a depth to bedrock of 1 m or less. For the considered location, this result suggests that an increase in frequency and intensity of rainstorms should predominantly result in an increase of landslide frequency, but without increasing the size of the largest landslides. As a more general implication, the contribution of large landslides to the total hazard may be overestimated if soil thickness is not considered, in particular if the present‐day hazard is projected to future scenarios.
    Beschreibung: The spatial pattern and size distribution of soil‐borne landslides in low mountain ranges investigated using a combination of remote sensing, geophysical surveying, and geotechnical testing reveal a cutoff in the distribution at large landslide sizes and possible overestimation of future scenarios.
    Schlagwort(e): ddc:551.307
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    Publikationsdatum: 2022-03-30
    Beschreibung: Fjords are recognized as hotspots of organic carbon (OC) burial in the coastal ocean. In fjords with glaciated catchments, glacier discharge carries large amounts of suspended matter. This sedimentary load includes OC from bedrock and terrigenous sources (modern vegetation, peat, soil deposits), which is either buried in the fjord or remineralized during export, acting as a potential source of CO2 to the atmosphere. In sub‐Antarctic South Georgia, fjord‐terminating glaciers have been retreating during the past decades, likely as a response to changing climate conditions. We determine sources of OC in surface sediments of Cumberland Bay, South Georgia, using lipid biomarkers and the bulk 14C isotopic composition, and quantify OC burial at present and for the time period of documented glacier retreat (between 1958 and 2017). Petrogenic OC is the dominant type of OC in proximity to the present‐day calving fronts (60.4 ± 1.4% to 73.8 ± 2.6%) and decreases to 14.0 ± 2.7% outside the fjord, indicating that petrogenic OC is effectively buried in the fjord. Beside of marine OC, terrigenous OC comprises 2.7 ± 0.5% to 7.9 ± 5.9% and is mostly derived from modern plants and Holocene peat and soil deposits that are eroded along the flanks of the fjord, rather than released by the retreating fjord glaciers. We estimate that the retreat of tidewater glaciers between 1958 and 2017 led to an increase in petrogenic carbon accumulation of 22% in Cumberland West Bay and 6.5% in Cumberland East Bay, suggesting that successive glacier retreat does not only release petrogenic OC into the fjord, but also increases the capacity of OC burial.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:552 ; ddc:551.9
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    Publikationsdatum: 2022-03-30
    Beschreibung: Cell size is a master trait in the functional ecology of phytoplankton correlating with numerous morphological, physiological, and life‐cycle characteristics of species that constrain their nutrient use, growth, and edibility. In contrast to well‐known spatial patterns in cell size at macroecological scales or temporal changes in experimental contexts, few data sets allow testing temporal changes in cell sizes within ecosystems. To analyze the temporal changes of intraspecific and community‐wide cell size, we use the phytoplankton data derived from the Lower Saxony Wadden Sea monitoring program, which comprises sample‐ and species‐specific measurements of cell volume from 1710 samples collected over 14 yr. We find significant reductions in both the cell volume of most species and the weighted mean cell size of communities. Mainly diatoms showed this decline, whereas the size of dinoflagellates seemed to be less responsive. The magnitude of the trend indicates that cell volumes are about 30% smaller now than a decade ago. This interannual trend is overlayed by seasonal cycles with smaller cells typically observed in summer. In the subset of samples including environmental conditions, small community cell size was strongly related to high temperatures and low total phosphorus concentration. We conclude that cell size captures ongoing changes in phytoplankton communities beyond the changes in species composition. In addition, based on the changes in species biovolumes revealed by our analysis, we warn that using standard cell size values in phytoplankton assessment will not only miss temporal changes in size, but also lead to systematic errors in biomass estimates over time.
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: Interreg V A program Deutschland‐Nederland of the European Union
    Beschreibung: Niedersächsisches Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/501100010570
    Beschreibung: https://doi.org/10.5281/zenodo.5799263
    Schlagwort(e): ddc:579.8 ; ddc:577.2
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Publikationsdatum: 2022-03-30
    Beschreibung: As evidenced by isotope geochemistry, the persistence of primitive reservoirs indicates that the earth's lower mantle is likely to be heterogeneous. Such heterogeneity could be a legacy from magma‐ocean (MO) solidification. The viscosity of MO is a key parameter to constrain the solidification type of MO. Here we directly measure the viscosity of peridotite (an analog of MO composition) melt at the pressure‐temperature conditions of the deep mantle, using the in situ falling sphere method. The viscosity of peridotite melt along liquidus is in the range of 38–17 mPa s at pressures from 7 to 25 GPa, which is 0.9–0.4 times of the estimation based on the viscosity of endmember compositions. Low viscosity favors fractional solidification and chemically layering of the early mantle at least to the top lower mantle, which could be a source of heterogeneity for the present mantle.
    Beschreibung: Plain Language Summary: The earth experiences a large‐scale melting and forms a deep magma ocean in its early history. The viscosity of peridotite melt is a key parameter for understanding the solidification type of magma ocean, which leads to the primitive mantle structure. This study directly measured the viscosity of peridotite melt to deep mantle conditions and revealed that peridotite melt has a lower value of viscosity than expected. The low viscosity of peridotite melt suggests a fractional solidification of the magma ocean, which supports a heterogeneous primitive mantle.
    Beschreibung: Key Points: The viscosity of peridotite melt has been measured down to lower‐mantle conditions by in situ falling sphere viscometry. Peridotite melt has a lower viscosity than expected from the viscosity of the endmembers. The low viscosity of peridotite melt suggests a fractional solidification in the magma ocean, supporting a heterogeneous primitive mantle.
    Beschreibung: MEXT | Japan Society for the Promotion of Science (JSPS) http://dx.doi.org/10.13039/501100001691
    Beschreibung: Grant‐in‐aid for Scientific Research
    Beschreibung: European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program
    Beschreibung: https://doi.org/10.5281/zenodo.5512934
    Schlagwort(e): ddc:552.1 ; ddc:551.12
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Publikationsdatum: 2022-03-31
    Beschreibung: In this paper, the methods of digital rock physics are applied to determine pressure‐dependent effective thermal conductivity in rock samples. Simulations are performed with an in‐house three‐dimensional finite volume code. In the first step, four numerical models are derived from a given tomographic scan of Berea sandstone. Consequently, simulations of the thermal conductivity at ambient conditions are performed and validated with experimental data. In a second step, a new workflow for the determination of the pressure‐dependent thermal conductivity in rock samples is elaborated, tested and calibrated. Results originating from the derived workflow show very good agreement with experimental data.
    Beschreibung: ttps://www.rockphysics.org/index.php/downloads
    Schlagwort(e): ddc:552.06
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Publikationsdatum: 2022-03-31
    Beschreibung: Radial diffusion is one of the dominant physical mechanisms driving acceleration and loss of radiation belt electrons. A number of parameterizations for radial diffusion coefficients have been developed, each differing in the data set used. Here, we investigate the performance of different parameterizations by Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Brautigam et al. (2005), https://doi.org/10.1029/2004ja010612, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, Ali et al. (2015), https://doi.org/10.1002/2014ja020419; Ali et al. (2016), https://doi.org/10.1002/2016ja023002; Ali (2016), and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 on long‐term radiation belt modeling using the Versatile Electron Radiation Belt (VERB) code, and compare the results to Van Allen Probes observations. First, 1‐D radial diffusion simulations are performed, isolating the contribution of solely radial diffusion. We then take into account effects of local acceleration and loss showing additional 3‐D simulations, including diffusion across pitch‐angle, energy, and mixed diffusion. For the L* range studied, the difference between simulations with Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 parameterizations is shown to be small, with Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344 offering the smallest averaged (across multiple energies) absolute normalized difference with observations. Using the Ali et al. (2016), https://doi.org/10.1002/2016ja023002 parameterization tended to result in a lower flux than both the observations and the VERB simulations using the other coefficients. We find that the 3‐D simulations are less sensitive to the radial diffusion coefficient chosen than the 1‐D simulations, suggesting that for 3‐D radiation belt models, a similar result is likely to be achieved, regardless of whether Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 parameterizations are used.
    Beschreibung: Key Points: 3‐D simulations using different radial diffusion coefficients, except Ali et al. (2016), produce similar results. Using Ali et al. (2016) DLL, simulated flux is significantly lower than observations. 3‐D modeling with Brautigam and Albert (2000) DLL results in a slightly smaller normalized difference (averaged over energies) to observations.
    Beschreibung: National Aeronautics and Space Administration (NASA) http://dx.doi.org/10.13039/100000104
    Beschreibung: European Union's Horizon 2020
    Beschreibung: https://doi.org/10.25346/S6/U9WFPD
    Schlagwort(e): ddc:538.7
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    facet.materialart.
    Unbekannt
    John Wiley & Sons, Ltd | Chichester, UK
    Publikationsdatum: 2022-03-31
    Beschreibung: Aerosol can affect clouds in various ways. Beside the microphysical impact of aerosol particles on cloud formation, the interference of aerosol with atmospheric radiation leads to changes in local heating, surface fluxes and thus mesoscale circulations, all of which may also modify clouds. Rather little is known about these so‐called semi‐direct effects in realistic settings – a reason why this study investigates the impact of absorbing aerosol particles on cloud and radiation fields over Germany. Using advanced high‐resolution simulations with grid spacings of 312 and 625 m, numerical experiments with different aerosol optical properties are contrasted using purely scattering aerosol as a control case and realistic absorbing aerosol as a perturbation. The combined effect of surface dimming and atmospheric heating induces positive temperature and negative moisture anomalies between 800 and 900 hPa, impacting low‐level cloud formation. Decreased relative humidity as well as increased atmospheric stability below clouds lead to a reduction of low‐level cloud cover, liquid water path and precipitation. It is further found that direct and semi‐direct effects of absorbing aerosol forcing have similar magnitudes and contribute equally to a reduction of net radiation at the top of the atmosphere.
    Beschreibung: Atmospheric aerosol particles can absorb solar radiation, altering the thermal structure of the atmosphere and surface fluxes. Using advanced high‐resolution simulations over Germany with grid spacings of 312 and 625 m, we find that boundary‐layer absorbing aerosol reduces low‐level cloud cover, liquid water path and precipitation. Direct and semi‐direct effects have similar magnitudes and contribute equally to a positive absorbing aerosol forcing.
    Beschreibung: German Ministry for Education and Research EU Horizon 2020 project CONSTRAIN
    Beschreibung: https://cera-www.dkrz.de/WDCC/ui/cerasearch/entry?acronym=DKRZ_LTA_1174_ds00001
    Schlagwort(e): ddc:551.5
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Publikationsdatum: 2022-03-31
    Beschreibung: Earth angular momentum forecasts are naturally accompanied by forecast errors that typically grow with increasing forecast length. In contrast to this behavior, we have detected large quasi‐periodic deviations between atmospheric angular momentum wind term forecasts and their subsequently available analysis. The respective errors are not random and have some hard to define yet clearly visible characteristics which may help to separate them from the true forecast information. These kinds of problems, which should be automated but involve some adaptation and decision‐making in the process, are most suitable for machine learning methods. Consequently, we propose and apply a neural network to the task of removing the detected artificial forecast errors. We found that a cascading forward neural network model performed best in this problem. A total error reduction with respect to the unaltered forecasts amounts to about 30% integrated over a 6‐days forecast period. Integrated over the initial 3‐days forecast period, in which the largest artificial errors are present, the improvements amount to about 50%. After the application of the neural network, the remaining error distribution shows the expected growth with forecast length. However, a 24‐hourly modulation and an initial baseline error of 2 × 10−8 became evident that were hidden before under the larger forecast error.
    Beschreibung: Plain Language Summary: Variations in Earth rotation can be described by changes in Earth angular momentum. Angular momentum functions are calculated from mass redistributions, for example, given by atmospheric models. Typically, atmospheric model forecasts are naturally accompanied by forecast errors that grow with increasing forecast length. In contrast to this behavior, atmospheric angular momentum wind term forecasts show large quasi‐periodic deviations when compared to their subsequently available model analysis data. The detected errors are not random and have some hard to define yet clearly visible characteristics. A postprocessing step using machine learning methods was established to remove the detected artificial forecast errors. A cascading forward neural network approach was able to reduce the forecast error by about 50% for the first forecast days and about 30% for a 6‐day forecast horizon. Moreover, the remaining error distribution shows the expected growth with forecast length. This postprocessing step improves atmospheric angular momentum forecasts without touching the numerical weather prediction model itself. Improved angular momentum forecasts should help to further decrease Earth rotation predictions errors.
    Beschreibung: Key Points: Motion terms of atmospheric angular momentum forecasts contain systematic errors. Machine learning is used to learn and reduce these errors. Remaining stochastic errors show modulations with a 24‐hr period.
    Beschreibung: http://esmdata.gfz-potsdam.de:8080/repository
    Schlagwort(e): ddc:551.51
    Sprache: Englisch
    Materialart: doc-type:article
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  • 91
    Publikationsdatum: 2022-03-31
    Beschreibung: Compound weather and climate events are combinations of climate drivers and/or hazards that contribute to societal or environmental risk. Studying compound events often requires a multidisciplinary approach combining domain knowledge of the underlying processes with, for example, statistical methods and climate model outputs. Recently, to aid the development of research on compound events, four compound event types were introduced, namely (a) preconditioned, (b) multivariate, (c) temporally compounding, and (d) spatially compounding events. However, guidelines on how to study these types of events are still lacking. Here, we consider four case studies, each associated with a specific event type and a research question, to illustrate how the key elements of compound events (e.g., analytical tools and relevant physical effects) can be identified. These case studies show that (a) impacts on crops from hot and dry summers can be exacerbated by preconditioning effects of dry and bright springs. (b) Assessing compound coastal flooding in Perth (Australia) requires considering the dynamics of a non‐stationary multivariate process. For instance, future mean sea‐level rise will lead to the emergence of concurrent coastal and fluvial extremes, enhancing compound flooding risk. (c) In Portugal, deep‐landslides are often caused by temporal clusters of moderate precipitation events. Finally, (d) crop yield failures in France and Germany are strongly correlated, threatening European food security through spatially compounding effects. These analyses allow for identifying general recommendations for studying compound events. Overall, our insights can serve as a blueprint for compound event analysis across disciplines and sectors.
    Beschreibung: Plain Language Summary: Many societal and environmental impacts from events such as droughts and storms arise from a combination of weather and climate factors referred to as a compound event. Considering the complex nature of these high‐impact events is crucial for an accurate assessment of climate‐related risk, for example to develop adaptation and emergency preparedness strategies. However, compound event research has emerged only recently, therefore our ability to analyze these events is still limited. In practice, studying compound events is a challenging task, which often requires interaction between experts across multiple disciplines. Recently, compound events were divided into four types to aid the framing of research on this topic, but guidelines on how to study these four types are missing. Here, we take a pragmatic approach and—focusing on case studies of different compound event types—illustrate how to address specific research questions that could be of interest to users. The results allow identifying recommendations for compound event analyses. Furthermore, through the case studies, we highlight the relevance that compounding effects have for the occurrence of landslides, flooding, vegetation impacts, and crop failures. The guidelines emerged from this work will assist the development of compound event analysis across disciplines and sectors.
    Beschreibung: Key Points: Using case studies representative of four main compound event types we show how compound event‐related research questions can be tackled. We present user‐friendly guidelines for compound event analysis applicable to different compound event types. We demonstrate that compound events cause vegetation impacts, coastal flooding, landslides, and continental‐scale crop yield failures.
    Beschreibung: European COST action DAMOCLES
    Beschreibung: NERC
    Beschreibung: Swiss National Science Foundation
    Beschreibung: Helmholtz Initiative and Networking Fund
    Beschreibung: Netherlands Organisation for Scientific Research (NWO)
    Beschreibung: Fundação para a Ciência e a Tecnologia
    Beschreibung: Scientific Employment Stimulus 2017
    Beschreibung: Italian Ministry of University and Research
    Beschreibung: European Union's Horizon 2020 research and innovation programme
    Beschreibung: AXA Research Fund for support
    Beschreibung: Portuguese Foundation for Science and Technology
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Publikationsdatum: 2022-03-31
    Beschreibung: Although previous findings support an origin of the Shatsky Rise igneous plateau (Northwest Pacific) through interaction of a mantle plume with a mid‐ocean ridge triple junction, the evidence for the involvement of a mantle plume is equivocal. The identification of an intraplate hotspot track emanating from the plateau could solve this controversy. Here we present major and trace element geochemical data from two different bathymetric features that emanate from the youngest end of Shatsky Rise: Papanin Ridge and the Ojin Rise Seamount province. Combining our results with plate tectonic reconstructions, we conclude that Papanin Ridge represents a hotspot track formed by plume‐ridge interaction. Whereas the southwestern part was formed along the path of the retreating Pacific‐Farallon‐Izanagi triple junction, the northeastern part was built by preferential drainage into its Pacific‐Farallon branch. In contrast, the Ojin Rise Seamounts formed as a true intraplate hotspot track of the Shatsky plume tail. Our wide‐ranging study reveals systematic spatial geochemical variations, consistent with a lithospheric thickness control on magma composition derived from melting a heterogeneous plume source. The recognition of two hotspot tracks and in particular of the Ojin Rise Seamounts as an intraplate hotspot track that is directly linked to Shatsky plateau volcanism both in terms of geochemistry and plate tectonic reconstructions confirms the long‐disputed involvement of a mantle plume for the formation of Shatsky Rise.
    Beschreibung: Plain Language Summary: The origin of Shatsky Rise, a large igneous plateau in the NW Pacific, has long been debated. It could have either formed by shallow mantle melting due to its confirmed creation along a mid‐ocean ridge or with additional contribution of deeper mantle material that upwelled as so‐called mantle plume beneath the spreading ridge (“plume‐ridge interaction”). The identification of an intraplate hotspot track emanating from Shatsky Rise and related to the plateau could answer this question. Here we present major and trace element geochemical data from lava samples dredged from two different structures that arise from the youngest end of the Shatsky Rise plateau: Papanin Ridge and the Ojin Rise Seamount province. By combining our results with plate tectonic reconstructions, we conclude that Papanin Ridge formed, like the main Shatsky Rise, by continued plume‐ridge interaction. In contrast, the Ojin Rise Seamounts formed as a true intraplate hotspot track by the drift of the Pacific Plate over the stationary Shatsky hotspot (plume tail). The recognition of an intraplate hotspot track that is directly linked to the Shatsky plateau volcanism both in terms of geochemistry and plate tectonic reconstructions also confirms the involvement of a mantle plume for the formation of Shatsky Rise.
    Beschreibung: Key Points: The Ojin Rise Seamounts are identified as intraplate hotspot track of the same mantle plume that formed the Shatsky Rise oceanic plateau. Papanin Ridge formed by plume‐ridge interaction and represents the northeastern continuation of the Shatsky plateau. Linking an intraplate hotspot track to the Shatsky plateau confirms the involvement of a mantle plume for its formation.
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: GEOMAR Helmholtz Centre for Ocean Research Kiel
    Beschreibung: https://doi.org/10.26022/IEDA/111976
    Schlagwort(e): ddc:551 ; ddc:552.2
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Publikationsdatum: 2022-03-31
    Beschreibung: Twenty‐first‐century climate change projections are uncertain, especially on regional scales. An important source of uncertainty is that climate models exhibit biases, which limits their ability to predict climate. One of the largest biases is the too warm sea surface temperature (SST) in the eastern tropical Atlantic (TA), reflecting deficient atmospheric and oceanic circulation. Here, we show that CO2‐forced TA‐sector climate changes simulated by state‐of‐the‐art climate models exhibit a strong mean‐state dependence. In particular, models simulating largest SST warming in the eastern TA, consistent with the warming observed since the mid‐20th century, typically exhibit a more realistic mean state than models simulating largest warming in the western TA. The former models exhibit a larger climate sensitivity, and predict stronger and in part qualitatively different climate changes over the TA sector, for example in precipitation. These findings may help to reducing uncertainty in TA‐climate change projections.
    Beschreibung: Plain Language Summary: Twenty‐first‐century climate change projections are uncertain, especially on regional scales. An important source of uncertainty is that climate models exhibit biases, which limits their ability to predict climate. One of the largest biases is the too warm sea surface temperature in the eastern tropical Atlantic (TA), reflecting deficient atmospheric and oceanic circulation. Here, we show that CO2‐forced TA‐sector climate changes simulated by state‐of‐the‐art climate models exhibit a strong relationship to the quality of simulating the mean state. These findings may help to reducing uncertainty in climate change projections over the TA sector.
    Beschreibung: Key Points: Climate projections for the tropical Atlantic sector depend on the quality of simulating present‐day conditions. Less biased climate models provide more reliable projections. Spread in CO2‐forced climate changes over the Tropical Atlantic region.
    Beschreibung: Helmholtz Society
    Beschreibung: JPI Climate and JPI Ocean
    Beschreibung: German Ministry of Education and Research
    Beschreibung: https://www.dkrz.de/up/services/data-management/cmip-data-pool
    Beschreibung: https://www.metoffice.gov.uk/hadobs/hadisst/
    Beschreibung: https://psl.noaa.gov/data/gridded/data.noaa.ersst.v5.html
    Beschreibung: https://psl.noaa.gov/data/gridded/data.cobe2.html
    Beschreibung: https://rda.ucar.edu/datasets/ds090.2/
    Beschreibung: https://psl.noaa.gov/data/gridded/data.hadslp2.html
    Beschreibung: http://www.esrl.noaa.gov/psd/data/gridded/data.coads.2deg.html
    Schlagwort(e): ddc:551.6
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Publikationsdatum: 2022-03-31
    Beschreibung: Early‐diagenetic cementation of tropical carbonates results from the combination of numerous physico‐chemical and biological processes. In the marine phreatic environment it represents an essential mechanism for the development and stabilization of carbonate platforms. However, diagenetic cements that developed early in the marine phreatic environment are likely to become obliterated during later stages of meteoric or burial diagenesis. When lithified sediment samples are studied, this complicates the recognition of processes involved in early cementation, and their geological implications. In this contribution, a petrographic microfacies analysis of Holocene Halimeda segments collected on a coral island in the Spermonde Archipelago, Indonesia, is presented. Through electron microscopical analyses of polished samples, this study shows that segments are characterized by intragranular cementation of fibrous aragonite, equant High‐Mg calcite (3.9 to 7.2 Mol% Mg), bladed Low‐Mg calcite (0.4 to 1.0 Mol% Mg) and mini‐micritic Low‐Mg calcite (3.2 to 3.3 Mol% Mg). The co‐existence and consecutive development of fibrous aragonite and equant High‐Mg calcite results initially from the flow of oversaturated seawater along the aragonite template of the Halimeda skeleton, followed by an adjustment of cement mineralogy towards High‐Mg calcite as a result of reduced permeability and fluid flow rates in the pores. Growth of bladed Low‐Mg calcite cements on top of etched substrates of equant High‐Mg calcite is explained by shifts in pore water pH and alkalinity through microbial sulphate reduction. Microbial activity appears to be the main trigger for the precipitation of mini‐micritic Low‐Mg calcite as well, based on the presumable detection of an extracellular polymeric matrix during an early stage of mini‐micrite Low‐Mg calcite cement precipitation. Radiocarbon analyses of five Halimeda segments furthermore indicate that virtually complete intragranular cementation in the marine phreatic environment with thermodynamically/kinetically controlled aragonite and High‐Mg calcite takes place in about 100 years. Collectively, this study shows that early‐diagenetic cements are highly diverse and provides new quantitative constraints on the rate of diagenetic cementation in tropical carbonate factories.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.pangaea.de/10.1594/PANGAEA.923980
    Schlagwort(e): ddc:552.5
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Publikationsdatum: 2022-03-31
    Beschreibung: Mixed sand‐ and gravel‐bed rivers record erosion, transport, and fining signals in their bedload size distributions. Thus, grain‐size data are imperative for studying these processes. However, collecting hundreds to thousands of pebble measurements in steep and dynamic high‐mountain river settings remains challenging. Using the recently published digital grain‐sizing algorithm PebbleCounts, we were able to survey seven large (≥ 1,000 m2) channel cross‐sections and measure thousands to tens‐of‐thousands of grains per survey along a 100‐km stretch of the trunk stream of the Toro Basin in Northwest Argentina. The study region traverses a steep topographic and environmental gradient on the eastern margin of the Central Andean Plateau. Careful counting and validation allows us to identify measurement errors and constrain percentile uncertainties using large sample sizes. In the coarse ≥2.5 cm fraction of bedload, only the uppermost size percentiles (≥95th) vary significantly downstream, whereas the 50th and 84th percentiles show less variability. We note a relation between increases in these upper percentiles and along‐channel junctions with large, steep tributaries. This signal is strongly influenced by lithology and geologic structures, and mixed with local hillslope input. In steep catchments like the Toro Basin, we suggest nonlinear relationships between geomorphic metrics and grain size, whereby the steepest parts of the landscape exert primary control on the upper grain‐size percentiles. Thus, average or median metrics that do not apply weights or thresholds to steeper topography may be less predictive of grain‐size distributions in such settings.
    Beschreibung: Plain Language Summary: Rock fragments on hillsides are transported to rivers, eventually becoming pebbles, sand, and mud as they are carried downstream by flowing water. The initial size of the pebbles, the way the size changes downstream, and the overprinting of the sizes with new pebbles from other hills and tributaries all form a complex process that can be difficult to disentangle. Yet studying the size of the pebbles at a given stream location or in a sedimentary deposit can provide insights into the conditions of their transport in terms of local upstream patterns of erosion, tectonics, and climate. We show that just looking at the size of the large pebbles on a riverbed can be used to infer the sources of material, but, since there are fewer large pebbles, they require more measurements to quantify. This necessitates new methods for pebble measurement using modern image‐processing tools.
    Beschreibung: Key Points: Complex grain‐size distributions in dynamic mountain rivers can be computed via thousands of measurements from PebbleCounts. Many measurements allow robust estimation of higher percentiles and we observe the most significant changes in the ≥95th percentile. Downstream grain‐size variation is nonlinearly related to variations in topographic steepness and lithology.
    Beschreibung: Deutsches Zentrum für Luft‐ und Raumfahrt (DLR) http://dx.doi.org/10.13039/501100002946
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: Brandenburger Staatsministerium für Wissenschaft, Forschung und Kultur (MWFK) http://dx.doi.org/10.13039/501100004581
    Beschreibung: https://zenodo.org/record/5089789
    Schlagwort(e): ddc:551.3 ; ddc:550
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Publikationsdatum: 2022-03-31
    Beschreibung: The local ensemble transform Kalman filter (LETKF) suggested by Hunt et al., 2007 is a very popular method for ensemble data assimilation. It is the operational method for convective‐scale data assimilation at Deutscher Wetterdienst (DWD). At DWD, based on the LETKF, three‐dimensional volume radar observations are assimilated operationally for the operational ICON‐D2. However, one major challenge for the LETKF is the situation where observations show precipitation (reflectivity) whereas all ensemble members do not show such reflectivity at a given point in space. In this case, there is no sensitivity of the LETKF with respect to the observations, and the analysis increment based on the observed reflectivity is zero. The goal of this work is to develop a targeted covariance inflation (TCI) for the assimilation of 3D‐volume radar data based on the LETKF, adding artificial sensitivity and making the LETKF react properly to the radar observations. The basic idea of the TCI is to employ an additive covariance inflation as entrance point for the LETKF. Here, we construct perturbations to the simulated observation which are used by the core LETKF assimilation step. The perturbations are constructed such that they exhibit a correlation between humidity and reflectivity. This leads to a change in humidity in such a way that precipitation is more likely to occur. We describe and demonstrate the theoretical basis of the method. We then present a case study where targeted covariance inflation leads to a clear improvement of the LETKF and precipitation forecast. All examples are based on the German radar network and the ICON‐D2 model over Central Europe.
    Beschreibung: The goal of this work is to develop a targeted covariance inflation (TCI) for the assimilation of 3D‐volume radar data based on the local ensemble transform Kalman filter (LETKF), adding artificial sensitivity and making the LETKF react properly to the radar observations. Perturbations to the simulated observations are constructed such that they exhibit an empirically derived correlation between humidity and reflectivity. This leads to a change in humidity in such a way that precipitation is more likely to occur.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): ddc:551.5
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Publikationsdatum: 2022-03-31
    Beschreibung: The tropical temperature in the free troposphere deviates from a theoretical moist‐adiabat. The overall deviations are attributed to the entrainment of dry surrounding air. The deviations gradually approach zero in the upper troposphere, which we explain with a buoyancy‐sorting mechanism: the height to which individual convective parcels rise depends on parcel buoyancy, which is closely tied to the impact of entrainment during ascent. In higher altitudes, the temperature is increasingly controlled by the convective parcels that are warmer and more buoyant because of weaker entrainment effects. We represent such temperature deviations from moist‐adiabats in a clear‐sky one‐dimensional radiative‐convective equilibrium model. Compared with a moist‐adiabatic adjustment, having the entrainment‐induced temperature deviations lead to higher clear‐sky climate sensitivity. As the impact of entrainment depends on the saturation deficit, which increases with warming, our model predicts even more amplified surface warming from entrainment in a warmer climate.
    Beschreibung: Plain Language Summary: The tropical temperature structure is determined by regions with deep convection, which is believed to be moist‐adiabatic. However, both models and observations show that the temperature deviates from moist‐adiabats. This is because convective parcels often mix with dry environmental air during ascent, pushing the temperature away from the moist‐adiabatic structure. More importantly, the tropical temperature is not dominated by one or a few strongest convective plumes, but rather controlled by the combined effect of many convective plumes of different strengths and depths. Therefore, the tropical temperature structure reflects the composition of convection happening at different values of boundary‐layer energy and mixing processes of variable efficiency with the environment. Using an idealized model, we find that representing such a deviation in the temperature structure increases the surface warming, because the resulting temperature lapse rate (LR) is more similar to a constant LR, showing less temperature increases higher than a moist‐adiabatic LR. This effect is likely amplified in a warmer climate due to this mixing process becoming more efficient in pushing the temperature further away from moist‐adiabats.
    Beschreibung: Key Points: The tropical temperature profile in the free troposphere deviates from that following a moist‐adiabatic lapse rate (LR). The deviations from the moist‐adiabatic LR can be explained by entrainment with a buoyancy‐sorting mechanism. The temperature deviations from moist‐adiabats increase climate sensitivity.
    Beschreibung: https://doi.org/10.5281/zenodo.1313687
    Beschreibung: https://cds.climate.copernicus.eu/cdsapp#%21/dataset/reanalysis-era5-pressure-levels-monthly-means?tab=overview
    Beschreibung: https://esgf-data.dkrz.de/projects/cmip6-dkrz/
    Beschreibung: http://hdl.handle.net/21.11116/0000-0008-FDA6-0
    Schlagwort(e): ddc:551.5
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Publikationsdatum: 2022-04-08
    Beschreibung: The benefit of biochar as a soil fertility enhancer is well known and has been broadly investigated. Equally, many tropical and subtropical countries use wastewater for irrigation in urban agriculture. To assess the related health risks, we determined pathogen and heavy metal fate associated with biochar application and wastewater irrigation in the urban agriculture of northern Ghana. Rice (Oryza L.) husk biochar (20 t ha−1), N–P–K 15–15–15 fertilizer (212.5 kg ha−1), and their combinations were evaluated in a field‐based experiment. Untreated wastewater and tap water served as irrigation water. Red amaranth (Amaranthus cruentus L.) was used as a test crop and was grown in wet (WS) and dry (DS) cropping seasons. Irrigation water, soil, and vegetables were analyzed for heavy metals, Escherichia coli, fecal coliform, helminth eggs, and Salmonella spp. Unlike the pathogens, analyzed heavy metals from irrigation water and soil were below the FAO/WHO permissible standard for agricultural activities. Wastewater irrigation caused E. coli concentrations ranging from 0.5 to 0.6 (WS) and from 0.7 to 0.8 (DS) log10 colony forming units per gram fresh weight (CFU gFW−1) on vegetables and from 1.7 to 2.1 (WS) and from 0.6 to 1.0 (DS) log10CFU per gram dry weight (gDW−1) in soil. Average log10CFU gFW−1 rates of 6.19 and 3.44 fecal coliform were found on vegetables, whereas in soil, 4.26 and 4.58 log10CFU gDW−1 were observed in WS and DS, respectively. Helminth egg populations were high in wastewater and were transferred to the crops and soil. Biochar did not affect bacteria contamination. Pathogen contamination on vegetables and in soil were directly linked to the irrigation water, with minimal or no difference observed from biochar application.
    Beschreibung: Core Ideas: Soil and vegetable contamination were linked to irrigation water source. Rice husk–derived biochar did not affect bacteria contamination on vegetables. Wastewater and biochar application did not affect heavy metal contamination in soil. Helminth eggs and bacteria pathogens in soil were not significantly affected by biochar.
    Beschreibung: Bundesministerium für Wirtschaftliche Zusammenarbeit und Entwicklung http://dx.doi.org/10.13039/501100006456
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): ddc:632.19
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Publikationsdatum: 2022-03-25
    Beschreibung: Bergordnung für die Bergwerke in der Grafschaft Lauterberg, erlassen von Heinrich XII. und Ernst V., Grafen von Hohnstein und Herren von Lohra und Klettenberg am 3. Februar 1528. Diese Bergordnung basiert auf der Bergordnung Herzog Georgs von Sachsen für Sankt Annaberg vom 5. Februar 1509. Von den 103 Paragraphen dieser Ordnung wurden 11 Paragraphen geändert und 3 Paragraphen hinzugefügt. Verwendet für diese Edition wurde die Annaberger Bergordnung, veröffentlicht im Codex Diplomaticus Saxoniae Regiae und die genannten Änderungen, 1791 veröffentlicht von Thomas Wagner in Corpvs Ivris Metallici Sammlung der neueſten und älterer Berggeſetze.
    Beschreibung: source
    Schlagwort(e): ddc:343.077 ; ddc:622
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 30
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    facet.materialart.
    Unbekannt
    In:  Johann Friedrich Klotzsch und Gottfried Immanuel Grundig in Sammlung vermischter Nachrichten zur sächsischen Geschichte Band 10
    Publikationsdatum: 2022-03-25
    Beschreibung: Bergordnung für den Schneeberg von Kurfürst Friedrich und den Herzögen Albrecht uns Johannes von Sachsen vom 19. Januar 1487. Nach dem Tod von Kurfürst Ernst im Jahr 1486 und der Leipziger Teilung im Jahr 1485, in der Schneeberg unter die gemeinsame Verwaltung der Albertiner und Ernestiner gekommen war, kam es offensichtlich auf dem Schneeberg zu einem gefühlten rechtsfreien Raum. Durch die offensichtliche Handlungsunfähigkeit der Landesherren nahmen Korruption und Betrug zu. Mit der neuen Bergordnung wollten die Landesherren Stärke und Einigkeit demonstrieren
    Beschreibung: source
    Schlagwort(e): ddc:343.077 ; ddc:622
    Sprache: Deutsch
    Materialart: doc-type:book , updatedVersion
    Format: 5
    Standort Signatur Erwartet Verfügbarkeit
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