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Results of palynological analysis from 2020 of the varved MO-05 core from Lake Mondsee (Austria) section (249-526 cm)

This study reports a precisely dated pollen record with a 20-year resolution from the varved sediments of Lake Mondsee in the north-eastern European Alps (47°49′N, 13°24′E, 481 m above sea level). The analysed part of core spans the interval between 1500 BCE and 500 CE and allows changes in vegetation composition in relation to climatic changes and human activities in the catchment to be inferred. Intervals of distinct but modest human impact are identified at ca. 1450-1220, 740-490 and 340-190 BCE and from 80 BCE to 180 CE. While the first two intervals are synchronous with prominent salt mining phases during the Bronze Age and Early Iron Age at the nearby UNESCO World Heritage Site of Hallstatt, the last two intervals fall within the Late Iron Age and Roman Imperial Era, respectively. Comparison with published records of extreme runoff events obtained from the same sediment core shows that human activities (including agriculture and logging) around Lake Mondsee were low during intervals of high flood frequency as indicated by a higher number of intercalated detrital event layers, but intensified during hydrologically stable intervals. Comparison of the pollen percentages of arboreal taxa with the stable oxygen isotope and potassium ion records of the NGRIP and GISP2 ice cores from Greenland reveals significant positive correlations for Fagus and negative correlations for Betula and Alnus. This underlines the sensitivity of vegetation around Lake Mondsee to temperature fluctuations in the North Atlantic as well as to moisture fluctuations controlled by changes in the intensity of the Siberian High and the North Atlantic Oscillation (NAO) regime.

The iron-snow regime in Fe-FeS cores: a numerical and experimental approach

In the Earth, the dynamo action is strongly linked to core freezing. There is a solid inner core, the growth of which provides a buoyancy flux that drives the dynamo. The buoyancy in this case derives from a difference in composition between the solid inner core and the fluid outer core. In planetary bodies smaller than the Earth, however, this core differentiation process may differ - Fe may precipitate at the core-mantle boundary (CMB) rather than in the center and may fall as iron snow and initially remelt with greater depth. A chemical stable sedimentation zone develops that comprises with time the entire core - at that time a solid inner core starts to grow. The dynamics of this system is not well understood and also whether it can generate a magnetic field or not. The Jovian moon Ganymede, which shows a present-day magnetic dipole field, is a candidate for which such a scenario has been suggested. We plan to study this Fe-snow regime with both a numerical and experimental approach. In the numerical study, we use a 2D/3D thermo-chemical convection model that considers crystallization and sinking of iron crystals together with the dynamics of the liquid core phase (for the 3D case the influence of the rotation of the Fe snow process is further studied).The numerical calculations will be complemented by two series of experiments: (1) investigations in metal alloys by means of X-ray radioscopy, and (2) measurements in transparent analogues by optical techniques. The experiments will examine typical features of the iron snow regime. On the one hand they will serve as a tool to validate the numerical approach and on the other hand they will yield important insight into sub-processes of the iron snow regime, which cannot be accessed within the numerical approach due to their complexity.

Wechselwirkungen zwischen saisonale arktische Meereisprozessen und Stabilität der Halokline – auf dem Weg zum Verständnis arktischer Gas- und Stoffflüsse

In Folge des globalen Klimawandels hat sich die Meereisdecke in der Arktis dramatisch verändert. Im derzeitigen Zustand spielt die arktische Eisdecke eine wichtige Rolle; so schirmt sie das Oberflächenwasser, die sogenannte arktische Halokline (Salzgehaltsschichtung), von der Erwärmung durch die sommerliche Sonneneinstrahlung ab. Zudem wird die Halokline durch die Salze, welches beim Gefrierprozess des Meerwassers aus der Kristallstruktur austritt, gebildet und stabilisiert. Gleichzeitig wirkt die Halokline als Barriere zwischen der Eisdecke und dem darunter liegenden warmen atlantischen Wasser und trägt so zum Erhalt der arktischen Meereisdecke bei. Dieses Gleichgewicht ist nun durch die insgesamt wesentlich dünnere arktische Meereisdecke und ihre verringerte sommerliche Ausdehnung gestört. Im Meerwasser sind zudem Gase und biogeochemisch wichtige Spurenstoffen enthalten. Diese werden durch die Gefrierprozesse eingeschlossen, beeinflusst und wieder ausgestoßen. So beeinflusst die Meereisdecke die Gas- und Stoffflüsse zwischen Atmosphäre, Eis und oberer Wasserschicht. Durch die Eisbewegung findet außerdem ein Transport statt z.B. in der sogenannten Transpolarendrift von den sibirischen Schelfgebieten, über den Nordpol, südwärts bis ins europäische Nordmeer. Nun wird mit den weitreichenden Veränderungen des globalen und arktischen Klimawandels bereits von der „neuen Arktis“ gesprochen, da angenommen wird, dass sich die Arktis bereits in einem neuen Funktionsmodus befindet. Dabei ist jedoch weitgehend unbekannt wie dieses neue System funktioniert, sich weiterentwickelt und wie sich dies auf die Eisbildungsprozesse und damit die Stabilität der Halokline und die damit verbundenen Gas- und Stoffflüsse auswirkt. Für solche Untersuchungen werden über den Jahresverlauf Proben der oberen Wassersäule und der Eisdecke benötigt. Ermöglicht wird dies durch die wissenschaftliche Initiative MOSAiC. Mithilfe der stabilen Isotope des Wassers (?18O und ?D) aus dem Eis und der Wassersäule kann Rückschlüsse auf die Herkunftswässer und den Gefrierprozess gezogen werden und diese Ergebnisse sollen in direkten Zusammenhang mit Gas- und biogeochemischen Stoffuntersuchungen (aus Partnerprojekten) gesetzt werden. Dabei können z.B. Stürme, Schmelzprozesse, Schneebedeckung, Teichbildung und Alterungseffekte des Eises eine Rolle spielen. Untersucht wird parallel die Veränderung der Wassersäule welche z.B. durch Wärmetransport, wiederum die Eisdecke beeinflussen kann.Diese prozessorientierten Untersuchungen der saisonalen Eisbildungsprozesse in Eis und Wassersäule der zentralen Arktis, werden einen wichtigen Beitrag zum Verständnis der Stabilität der arktischen Halokline und der arktischen Gas- und Stoffflüsse liefern. Da sich die Gase und Stoffe nicht-konservativ verhalten, während die Isotope im Gefrierprozess konservativ sind, erwarten wir aus der Diskrepanz wiederum wichtige Informationen z. B. über wiederholtes Einfrieren von Süßwasserbeimengungen ableiten zu können.

Landkreis Verden, Anlagen nach BImSchG

Anlagen nach dem Bundes-Immissionsschutzgesetz im Landkreis Verden

Quantified community composition of aquatic insect larvae with urbanization and environmental parameters in artificial microhabitats, Salzburg, June-August 2021

Urbanization affects ecological communities but urban ecology has mostly focused on large and charismatic species. Water-filled tree holes and other ephemeral small standing waters in cities constitute unique but inconspicuous breeding habitats for a range of insects. Their biodiversity is not well known and how their communities respond to increased urbanization in particular, has rarely been studied. Using a Citizen Science Project, we investigated how urbanization (measured as imperviousness, human population density and altered temperature), additional environmental parameters (pH, electric conductivity) and detritus serving as a food source affected larval insect communities in artificial aquatic microhabitats. We found that these habitats were colonized quickly by a range of insect taxa. Their community abundance, richness and decomposition rates were largely stable across different levels of urbanization. Fine detritus content increased larval abundance. Community composition shifted strongly with urbanization. The most abundant and frequent species in our study, the exotic mosquito species Aedes japonicus, responded negatively to imperviousness. Aquatic microhabitats could be shown to be important habitats for aquatic insects in cities. However, their community composition may change with increased urbanization. As our results showed, exotic species such as mosquitoes may dominate the communities in these habitats. In the case of vector species, high abundances may affect human and animal health via increased pathogen transmission. Therefore, we suggest raising awareness about potential risks of these habitats and possible measures preventing the establishment and spread of harmful species, while still supporting native biodiversity in urban spaces.

Bebauungsplan 060 Steuerung Tierhaltungsanlagen Munderloh 1. Aenderung

Bebauungsplan 060 Steuerung Tierhaltungsanlagen Munderloh 1. Aenderung im originären Datenformat

Water isotope values in samples collected June 2019, March 2020 and July 2020 along estuarine systems at the Baltic Sea coast

Stable isotopes (δ2H and δ18O) were analyzed in water samples collected at 68 spots along the Schlei, the Zingster Bodden chain, and the Rügener and Greifswalder Boddens in June 2019, March 2020, and July 2021. Transect samples were taken at shores from 0.3 to 0.6 m below water surface, using a pipette, and directly transferred into measurement vials. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water chemical parameters were measured in-situ with a WTW multiparameter device (Multi 3630 IDS), equipped with a WTW TetraCon 925 electrical conductivity measuring cell. The data give information about the spatial isotope variability along the transects.

Impact of long-term exposure to elevated pCO2 on activity and populations of free living N2 fixing organisms in a temperate grassland system

The project aims at achieving a better understanding of the processes that drive or limit the response of grassland systems in a world of increasing atmospheric pCO2. We will test the hypothesis that the previously shown increase in below-ground allocation of C under elevated pCO2 provides the necessary energy excess and will stimulate free-living N2 fixers in a low N grassland environment. The project thus aims at assessing the occurrence and importance of free-living N2 fixers under elevated pCO2 and identify the associated microbial communities involved in order to better understand ecosystems response and sustainability of grassland systems. This project had the last opportunity to obtain soil samples from a grassland ecosystem adapted to long-term (10 year) elevated atmospheric pCO2 as the Swiss FACE experiment. The project aims to identify the relevant components of free-living diazotrophs of the microbial community using 15N stable isotope - DNA probing.

Carbon chemistry, stable carbon and oxygen isotopes, and calculated pCO2 and CO2 fluxes over 15 months along the Wiesent karst headwater stream in northern Bavaria, Germany (March 2023-May 2024)

This dataset contains alkalinity, dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) concentrations, d13C values of DIC, DOC, and particulate organic carbon (POC), d18O values of dissolved oxygen, and calculated partial pressure of CO2 (pCO2), CO2 fluxes, and gas-transfer velocity (k600) from stream-water samples collected at 13 sites along the first 3.25 km of the Wiesent karst headwater stream in northern Bavaria, Germany, from March 2023 to May 2024. The dataset supports analyses of carbonate-system dynamics, oxygen cycling, and CO2 evasion under varying hydroclimatic conditions.

Diel carbon chemistry, stable carbon and oxygen isotopes, calculated pCO2 and CO2 fluxes during a 24 h survey in the Wiesent karst headwater, northern Bavaria, Germany (August 2023)

This dataset contains diel measurements of alkalinity, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC), d18O values of dissolved oxygen, and calculated partial pressure of CO2 (pCO2), calculated CO2 fluxes, and calculated gas-transfer velocity (k600) from stream-water samples collected at three sites along the Wiesent karst headwater stream in northern Bavaria, Germany, between 21 and 22 August 2023. Measurements were conducted at 4 h intervals over a 24 h period to assess short-term variability in carbon and oxygen cycling and CO2 evasion.

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