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Schwerpunktprogramm (SPP) 527: Bereich Infrastruktur - International Ocean Discovery Program, Untersuchung der Rolle von Vulkanismus am Beginn und Ende des Paläozän-Eozän-Temperaturemaximum basierend auf Sedimenten der IODP-Expedition 396

Es ist bekannt, dass Vulkanausbrüche das Klima auf verschiedene Weise beeinflussen. Diese reichen von kurzfristigen Auswirkungen wie Sulfat-Injektionen, die die einfallende Sonnenstrahlung reduzieren und zu Abkühlung führen, bis zu mittelfristigen Auswirkungen wie Erwärmung durch Kohlendioxid-Entgasung. Langfristig können Auswirkungen wie eine verstärkte Verwitterung eingelagerter Basalte zu einer Entfernung von Kohlendioxid und damit Abkühlung führen. Lange Perioden intensiven Vulkanismus, die als Large Igneous Provinces (LIPs) bekannt sind, können besonders tiefgreifende Auswirkungen auf das Klima haben, wobei mehrere LIPs entweder mit der globalen Erwärmung oder Abkühlung in der Erdgeschichte sowie mit Massenaussterben in Verbindung gebracht werden. Das Paläozän-Eozän-Temperaturemaximum (PETM), eine 200.000 Jahre lange Periode intensiver globaler Erwärmung vor ca. 56 Millionen Jahren, ereignete sich zur gleichen Zeit wie die Entstehung eines LIP, der North Atlantic Igneous Province (NAIP). Die NAIP-Entstehung wurde als Ursache für das PETM vorgeschlagen, da während des Vulkanismus Kohlendioxid und Methan freigesetzt werden, welches zu einer schnellen Erwärmung führt. Es wurde auch vermutet, dass die Ablagerung von Vulkanasche während des NAIP das Klima abgekühlt hat. Als solches ist das PETM eine ideale Periode, um die Auswirkungen des Vulkanismus auf das Erdsystem zu untersuchen. Expedition 396 des International Ocean Discovery Program (IODP) hat erfolgreich eine Reihe von langen Sedimentsequenzen aus dem PETM-Zeitalter am norwegischen Rand geborgen. In diesem Projekt beabsichtige ich, detaillierte deskriptive, geochemische und modellbasierte Untersuchungen mit den Sedimenten der Expedition 396 durchzuführen, um die Rolle des NAIP-Vulkanismus im PETM zu dokumentieren. Erstens wird die Intensität des Vulkanismus durch neue Schätzungen der Kohlendioxid-, Methan- und Sulfatemissionen bewertet, um die Rolle der Gase auf den Klimawandel zu bestimmen. Durch detaillierte geochemische Untersuchungen werden die Auswirkungen der Ascheablagerung auf den Kohlenstoffkreislauf bewertet mit Schwerpunkt auf der Rolle der Asche als Nährstofflieferant für Phytoplankton liegt. Die potenziellen Auswirkungen der Ascheablagerung auf die Speicherung von Kohlenstoff im Sediment werden ebenfalls geochemisch und isotopisch untersucht. Abschließend werden die Ergebnisse unter Verwendung von Erdsystemmodelle kombiniert, um die genaue Rolle des Vulkanismus im PETM zu bestimmen. Die erwarteten Ergebnisse werden uns neue Erkenntnisse über die Rolle der LIP-Entstehung und der Ablagerung von Vulkanasche beim Klimawandel geben. Sedimente von Expedition 396 bieten eine einzigartige Gelegenheit, den geochemischen Abdruck des Vulkanismus hochauflösend zu untersuchen. Die Ergebnisse dieser Arbeit werden zu einer erheblichen Verbesserung unseres Verständnisses des PETM führen.

Element concentrations from two benthic chambers and the ambient bottom water during an in-situ incubation experiment in July 2025

The dataset contains major and trace element concentrations measured by inductively coupled plasma optical emission spectrometry (ICP-OES) from water samples collected during a 16-day in-situ incubation experiment in the Baltic Sea (2025-07-12 to 2025-07-29). Samples were collected using an automated glass-syringe sampler deployed within two benthic chambers of a Biogeochemical Observatory (BIGO, Sommer et al., 2009) at 54° 34.432' N, 10° 10.776' E, at 22 m water depth. In one chamber, 29 g of fine calcite powder were added to the bottom water to assess the potential of enhanced benthic calcite weathering as an ocean alkalinity enhancement (OAE) strategy. Seven samples per chamber and from the ambient bottom water were analyzed to trace elemental changes associated with calcite dissolution.

Nutrient concentrations from two benthic chambers and the ambient bottom water during an in-situ incubation experiment in July 2025

The dataset contains dissolved nutrient concentrations from water samples collected during a 16-day in-situ incubation experiment in the Baltic Sea (2025-07-12 to 2025-07-29). Samples were collected using an automated glass-syringe sampler deployed within two benthic chambers of a Biogeochemical Observatory (BIGO, Sommer et al., 2009) at 54° 34.432' N, 10° 10.776' E, at 22 m water depth. In one chamber, 29 g of fine calcite powder were added to the bottom water as part of an enhanced benthic calcite weathering experiment. Seven samples per chamber and from the ambient bottom water were analyzed to assess potential nutrient fluxes associated with the calcite addition and benthic biogeochemical processes.

Alkalinity concentrations from two benthic chambers and the ambient bottom water during an in-situ incubation experiment in July 2025

The dataset contains total alkalinity measurements from water samples collected during a 16-day in-situ incubation experiment in the Baltic Sea (2025-07-12 to 2025-07-29). Samples were collected using an automated glass-syringe sampler deployed within two benthic chambers of a Biogeochemical Observatory (BIGO, Sommer et al., 2009) at 54° 34.432' N, 10° 10.776' E, at 22 m water depth. In one chamber, 29 g of fine calcite powder were added to the bottom water. Seven samples per chamber and from the ambient bottom water were taken to monitor alkalinity changes resulting from calcite dissolution, providing a direct measure of the ocean alkalinity enhancement (OAE)

Processed flow discharge data from the Neu Darchau gauging station between 1969 and 2019

The dataset includes processed flow discharge data from Neu Darchau gauging station (Elbe-km 536.4) that provided hydrological information for calculating alkalinity transport potential. The monthly sums were calculated from daily mean discharge measurements from Neu Darchau (station number: 6340110) available from the Global Runoff Data Centre (https://grdc.bafg.de/).

Total carbohydrates quantified in sediment cores from coastal vegetated ecosystems

50-cm deep sediment cores were taken in saltmarsh, seagrass, mangroves and unvegetated areas around the German Bight, Malaysia and Columbia in 2022 and 2023. Up to 3 points per ecosystem were sampled along a transect, in total 93 cores were analysed. Carbohydrates were sequentially extracted using MilliQ-water and 0.3 M EDTA for later analyses. The total carbohydrate content was assessed using the phenol-sulfuric acid assay (Dubois et al., 1956). Briefly, 100 µL of resuspended samples or extracts were mixed with 100 µL of 5% phenol solution, followed by the addition of 500 µL of concentrated sulfuric acid. The reaction mixture was incubated at room temperature for 10 minutes, then further incubated at 30°C for 20 minutes. Absorbance at 490 nm was measured using a Spectramax Id3 plate reader (Molecular Devices) and quantified against a glucose standard curve.

Polysaccharides quantified in sediment cores from coastal vegetated ecosystems

50-cm deep sediment cores were taken in saltmarsh, seagrass, mangroves and unvegetated areas around the German Bight, Malaysia and Columbia in 2022 and 2023. Up to 3 points per ecosystem were sampled along a transect, in total 93 cores were analysed. Carbohydrates were sequentially extracted using MilliQ-water and 0.3 M EDTA for later analyses. Polysaccharides were screened using microarray analysis following the method described by Vidal-Melgosa et al. (2022). Briefly, sediment extracts from MilliQ-water and EDTA were combined in equal volumes, and 30 µL of the mixture was transferred into wells of 384-microwell plates. Two consecutive two-fold dilutions were performed using a printing buffer (55.2% glycerol, 44% water, 0.8% Triton X-100). The plates were then centrifuged at 3,500 × g for 10 minutes at 15 °C. Each microarray was individually probed with a monoclonal antibody (mAb), and binding was detected using a secondary antibody conjugated to alkaline phosphatase. In the presence of its substrate, this reaction produced a colorimetric signal. Developed arrays were scanned at 2400 dots per inch, and binding signal intensity was quantified using Array-Pro Analyzer 6.3 software (Media Cybernetics).

Monosaccharides quantified in sediment cores from coastal vegetated ecosystems

50-cm deep sediment cores were taken in saltmarsh, seagrass, mangroves and unvegetated areas around the German Bight, Malaysia and Columbia in 2022 and 2023. Up to 3 points per ecosystem were sampled along a transect, in total 93 cores were analysed. Carbohydrates were sequentially extracted using MilliQ-water and 0.3 M EDTA for later analyses. Extracts were acid hydrolysed (1 M HCl, 24 h, 100°C) and monosaccharides were analysed using anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), according to Engel et al., 2011. Briefly, sample analysis was performed using a Dionex ICS-5000+ system with a CarboPac PA10 analytical column (2 × 250 mm) and a CarboPac PA10 guard column (2 × 50 mm). Neutral and amino sugars were separated under isocratic conditions with 18 mM NaOH, while acidic monosaccharides were separated using a gradient up to 200 mM NaCH₃COO.

Monosaccharides quantified in porewater samples from coastal vegetated ecosystems

Porewater was taken from 30 to 50 cm depths in saltmarsh, seagrass and unvegetated areas around the German Bight in 2022 and 2023. Up to 9 points per ecosystem were sampled along a transect. Polysaccharides >5kDa were upconcentrated using AMICON-filtration devide and afterwards freeze dried. Dired samples were resuspended in MilliQ-water and acid hydrolysed (1 M HCl, 24 h, 100°C). Monosaccharides were analysed using anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD, ThermoFisher Dionex ICS-5000+ system equipped with a CarboPac PA10 analytical column (2 x 250 mm) and a CarboPac PA10 guard column (2 x 50 mm)), according to Engel et al. (2011).

Polysaccharide fucoidan BAM1 and arabinogalactan-protein glycan JIM13 antibody binding in sediment cores from coastal vegetated ecosystems

50-cm deep sediment cores were taken in saltmarsh, seagrass, mangroves and unvegetated areas around the German Bight, Malaysia and Columbia in 2022 and 2023. Up to 3 points per ecosystem were sampled along a transect, in total 93 cores were analysed. Carbohydrates were sequentially extracted using MilliQ-water and 0.3 M EDTA for later analyses. For more specific analysis enzyme-linked immunosorbent assay (ELISA) was used for detection of fucoidan and arabinogalactan-protein glycan as described in the following studies (Vidal-Melgosa et al., 2021 and Cornuault et al., 2014). In short, 100 µL of sediment extracts were added to a pre-coated 96-well plate and incubated overnight at 4°C. The signal was developed using primary antibodies, BAM1 (fucoidan) and JIM13 (arabinogalactan-protein glycan), diluted 1:10 in skim milk PBS solution, followed by anti-rat antibody at a 1:1000 dilution in the same solution. Absorbance was measured at 450 nm using a Spectramax Id3 plate reader (Molecular Devices).

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