The Human and Earth System Coupled Research (HESCOR) project at the University of Cologne aims to increase interdisciplinary discussion in research related to the Earth and Human Systems by collaborating across disciplines to create model-tested hypotheses and analyze data. Given the broad range of jargon and data from researchers across the humanities, natural sciences, and social sciences, HESCOR promotes methods that lower barriers and encourage interdisciplinary discourse and data sharing to better link often diverse and distinct data from different disciplines. Within HESCOR, clearly defined workflows, protocols, and a 3-tiered database serve as the foundation of the interdisciplinary process. Standard workflows and protocols help structure conversations and set expectations so that HESCOR researchers can continue interdisciplinary dialogue and documentation throughout data processing. By organizing HESCOR data in well-defined tiers (Tier I – standardized metadata, Tier II – reorganized and quality-controlled data within a HESCOR framework, and Tier III – interpreted data), the HESCOR Database reflects the research stages of data analysis – processing data for modelling along the way. This structure allows HESCOR members to better communicate data interpretations across academic fields and formulate models that can help reconstruct causal links between the Human and Earth Systems. The HESCOR database prioritizes uniform metadata, substantial documentation, and clearly defined interpretations to provide orderly data across the natural sciences, social sciences, and humanities applicable to a broader set of researchers. Utilizing a soon-to-be published Late Pleistocene paleoenvironmental record from Lake Nakuru, Kenya, we demonstrate the workflow created at HESCOR to increase communication across disciplines to further understanding of the interplay between the Human and Earth Systems.

How to cite: Robakiewicz, E., Schlüter, P., and Foerster, V.: The HESCOR Database: Bridging Human and Earth Science Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10919, https://doi.org/10.5194/egusphere-egu25-10919, 2025.

The Blombos Cave, located on the southern coast of South Africa, is a key site for understanding the behavioural evolution of modern humans during the Middle Stone Age. This study examines the seasonal timing of shellfish collection and the marine climate's seasonality near Blombos Cave through stable oxygen isotope analysis of the marine gastropod Turbo sarmaticus. By analyzing the δ¹⁸O values in sequential growth increments of T. sarmaticus shells from archaeological layers, we reconstruct past sea surface temperatures (SSTs) and infer patterns of human occupation over the period 100–70 ka. The δ¹⁸O data show distinct seasonal fluctuations in SSTs with an amplitude of approximately 4°C. These fluctuations are consistent with the present-day seasonal variation in sea surface temperatures at Blombos Cave, which is influenced by the interaction between the Agulhas Current (bringing warmer waters from the Indian Ocean) and the Benguela Current (bringing cooler waters from the Atlantic). The isotopic evidence also provides insight into the seasonality of human occupation at Blombos Cave. Preliminary findings suggest that early Homo sapiens primarily inhabited the site during the warmer seasons, likely focusing on marine resource exploitation at that time. Ongoing research will incorporate clumped isotope analysis to provide an independent temperature proxy, improving our estimates of past oxygen isotopic composition in coastal waters and enhancing reconstructions of SST and occupation seasonality.

How to cite: Andersson, C., Milic’, J., Göktürk, O., and van Niekerk, K.: Seasonal Timing of Shellfish Collection and Paleoenvironmental Reconstruction from Archaeological Shells at Blombos Cave, South Africa, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16739, https://doi.org/10.5194/egusphere-egu25-16739, 2025.

Reconstructing past wind directions is critical in constraining synoptic scale climate regimes in the geologic past. Such wider scale understanding of past climate helps frame the climatic and environmental conditions that past human populations were exposed to. This is particularly important in regions such as Сentral Asia, at the interface of a range of climate zones. Palaeolithic tools are extensively embedded within the loess-palaeosol sequences of the Khovaling Loess Plateau, Southern Tajikistan, yet little is known about the environmental conditions these hominin groups faced.

Magnetic techniques applied to loess-palaeosol sequences are particularly insightful for investigating dust transport dynamics and variations in the intensity of hydroclimate. Anisotropy of magnetic susceptibility (AMS) in particular measures the magnetic fabric, i.e., the orientation of magnetic particles in an oriented sample, which can provide insights into palaeowind directions and post-depositional processes. Here we apply AMS to three different loess-palaeosol sections of the Khovaling Loess Plateau, approximately spanning the past 1 Ma, in order to assess if this technique allows us to reconstruct palaeowind directions for this region of Central Asia.

Our results reveal the first palaeowind directions reconstructed for the Khovaling Loess Plateau. We present AMS data from three sites on the Khovaling Loess Plateau and demonstrate the potential and limitations of this data for reconstructing palaeowind directions. We investigate the question to which degree local winds, responsible for loess deposition on the Khovaling Loess Plateau, are related to broader atmospheric circulation patterns. We also explore how AMS data can be combined with other palaeoenvironmental proxies, such as frequency-dependent magnetic susceptibility as an indicator of palaeoprecipitation, and how this technique can be used to assess sediment reworking.

How to cite: Schneider, R., Kulakova, E., Almqvist, B., and Stevens, T.: Magnetic fabric of Tajik loess-palaeosols as a palaeowind and process indicator, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3636, https://doi.org/10.5194/egusphere-egu25-3636, 2025.

In recent years the use of aeolian sand influx (ASI) analyses on ombrotrophic peat sequences (c.f. Björck and Clemmensen, 2004) has become an increasingly popular method for reconstructing past storminess. This method is based on the assumption that all mineral grains deposited on the surface of the hydrologically isolated bog must have been brought to the site by wind. Thus, changes in the amount and size of the mineral grains found over time/depth can be related to past storm frequency and intensity. During the last two decades, several different methods of quantifying ASI have been developed. Three major drawbacks of these methods are that they are (i) often time- and labour intensive; (ii) rely on high temperature dry ashing to remove organic material from samples before ASI quantification and (iii) non-continuous, requiring discrete sampling.

In an attempt to address these issues, we investigate whether X-ray computed tomography (CT) can be used to count and measure sand grains in peat. Drawing from the methods used by Cederstrøm et al. (2021) for IRD quantification in marine sediments, we added known amounts of sand (manually counted) in certain grain size fractions (63-1000, 125-1000, 63-125, 125-250, 250-500 and 500-1000 µm) and with known grain size distributions (laser diffraction) to test peat samples. The samples were then CT-scanned at a voxel resolution of 27.5 µm, and in the resulting 3D imagery, sand grains were identified, counted and measured using basic image processing tools. Our preliminary results indicate that it is possible to reliably count and measure sand grains in peat using a CT-based method, especially for grain sizes larger than 4-5 voxels (≥125 µm in this study). Grain size distributions for peat samples with sand grains ≥125 µm acquired through the CT method are strongly correlated to standard laser diffraction results (r = 0.81–0.98, p < 0.01). Similarly, CT-based and manual grain counts show a strong correlation (r = 0.94–1.00, p < 0.01) and the number of grains counted using the CT method differs on average by only 4 % from manual counts. Early-stage trials with full peat sequences further indicate that CT could be a reliable and efficient method for quantifying ASI and reconstructing past storm variability.

References

Björck, S., Clemmensen, L., 2004. Aeolian sediment in raised bog deposits, Halland, SW Sweden: A new proxy record of Holocene winter storminess variation in southern Scandinavia? Holocene 14, 677–688. https://doi.org/10.1191/0959683604hl746rp

Cederstrøm, J.M., van der Bilt, W.G.M., Støren, E.W.N., Rutledal, S., 2021. Semi-automatic ice-rafted debris quantification with computed tomography. Paleoceanography and Paleoclimatology 36, e2021PA004293. https://doi.org/10.1029/2021PA004293

How to cite: Palmgren, Y., O'Regan, M., and Kylander, M.: Reconstructing storminess from aeolian sand influx to peat bogs using X-ray computed tomography, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10564, https://doi.org/10.5194/egusphere-egu25-10564, 2025.

The Mediterranean Sea is expected to be one of the regions most severely impacted by current and future climate change. In fact, it is already experiencing more frequent and severe hydro-extremes (floods and droughts), which are to be exacerbated in the near future, together with thermal-extremes (heat and cold waves) as yet to be evaluated in seasonality and predictability. 

While past centennial-scale climate fluctuations in this region have already been investigated, however, little is known about higher frequency variability, i.e. variability at human timescales. This study aims to investigate the hydroclimate dynamics and Sea Surface Temperature (SST) variability over the past ~2,000 years at unprecedented temporal resolution, by using high-resolution biomarker analyses. 

Therefore, we integrated Mass Spectrometry Imaging (MSI) and conventional alkenone analysis to achieve sub-annual to decadal resolution in SST reconstructions from marine sediments collected in the Western Mediterranean and the Tagus areas from the Iberian margin. MSI is further combined with elemental proxies derived from μXRF mapping, including indicators of continental input and marine productivity.

Preliminary results reveal significant centennial-scale SST fluctuations and hydroclimate variability over the past ~2,000 years, including climatic transitions such as the Late Little Ice Age (LaLIA; 6th–7th centuries), the Little Ice Age (LIA; ca. 13th–19th centuries) and the Post-Industrial period (19th century onwards). We will present an overview of how these transitions impacted interannual to decadal climate variability. Such knowledge will advance our understanding of climate dynamics and their regional consequences, which is essential for addressing the associated societal-economic challenges.

Acknowledgements: The project that gave rise to these results received the support of a fellowship from the ”la Caixa” Foundation (ID LCF/BQ/DI24/12070003).

How to cite: Kapiri, M.-S., Wörmer, L., Lebreiro, S., Liu, W., Platikanov, S., Rodrigues, T., Salgueiro, E., Tobias, A., Taubner, H., Wendt, J., Obreht, I., Ziveri, P., and Martrat, B.: Interannual to decadal climate variability during the past 2,000 years in the Western Mediterranean using Mass Spectrometry Imaging, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18824, https://doi.org/10.5194/egusphere-egu25-18824, 2025.

Hyperspectral imaging (HSI) is revolutionising sediment core analysis in environmental and geoscience research, providing high-resolution, non-destructive insights into biogeochemical processes. However, analysing the large, complex datasets generated by HSI requires specialised tools. Existing commercial solutions often lack flexibility and transparency, hindering open science practices.

To address this, we introduce napari-sediment, an open-source plugin for the napari image analysis platform. This plugin provides a user-friendly graphical interface to implement a complete workflow for hyperspectral sediment core analysis, including:

• Preprocessing: Background correction and noise reduction.
• Data exploration: Interactive visualisation and statistical analysis of spectral data.
• Endmember extraction: Identification of pure spectral signatures.
• Quantitative analysis: Calculation of spectral indices for substance quantification and visualisation of spatial distributions.

napari-sediment streamlines the analysis of hyperspectral sediment core data, enabling researchers to efficiently extract valuable information on pigment distributions, mineral composition (limited), and organic matter content (qualitative). By leveraging the napari framework, the plugin fosters reproducibility and collaboration in the growing field of hyperspectral sedimentology. Here, we demonstrate the capabilities of napari-sediment and highlight its potential for advancing paleoclimate research, environmental monitoring, and geological investigations.

How to cite: Zahajská, P., Witz, G., and Grosjean, M.: napari-sediment: An open-source plugin for hyperspectral sediment core analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3814, https://doi.org/10.5194/egusphere-egu25-3814, 2025.

Understanding lithofacies, defined by distinct sedimentary characteristics, is fundamental for deciphering depositional processes and reconstructing paleo-environments. While conventional methods like visual core description and grain size analysis are widely employed, they often face challenges, such as incomplete observation of internal structures, discrete sampling intervals, and potential for subjective interpretations, which may hinder the accuracy of lithofacies identification. X-ray Computed Tomography (CT), a non-destructive, high-resolution, and widely applicable imaging technique, addresses these limitations by enabling three-dimensional visualization and quantitative analysis of sediment cores. This study evaluates the feasibility of CT in assisting lithofacies identification by analyzing two sediment cores from the Dapeng Bay region in southwestern Taiwan. Beyond its qualitative capability to reveal imperceptible structures, CT-derived parameters were employed to quantify sedimentary features, such as grain size variability and internal structures, including ratios of different CT-intensity ranges (indicating materials of varying density or composition), mean CT intensity, coefficient of variation, and morphological characteristics. By combining these parameters, fourteen lithofacies were identified and further grouped into three sedimentary facies: lagoonal, channel, and tidal flat. This facilitates the reconstruction of a 500-year depositional history, highlighting the transition from lagoonal to tidal flat systems and elucidating depositional mechanisms influenced by high-energy events. This study establishes an objective and standardized framework that integrates qualitative CT imaging with quantitative parameterization to assist lithofacies identification. By reliably capturing subtle sedimentary variations and enabling consistent application across multiple sediment cores, this approach also supports systematic examination of spatial coverage and provides valuable insights into sedimentary environments across temporal and spatial scales.

How to cite: Wu, Y.-H., Huang, J.-J. S., Yu, N.-T., Yen, J.-Y., Chyi, S.-J., and Chen, J.-H.: Enhancing Lithofacies Identification Through X-Ray Computed Tomography, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15147, https://doi.org/10.5194/egusphere-egu25-15147, 2025.

Annually laminated sediments (varves) are excellent paleoclimate archives because of their high temporal resolution and because they contain their own chronology that can be converted to calendar years. However, their studies can be tedious because they can be disturbed, irregular or very thin, sometimes less than a mm. Here we explore the potential of micro-computed tomography (µCT) to unlock paleoclimate signals from varved records.

First, we show the added value of performing varve counts and thickness measurements from a 3D volume instead of a randomly sampled single 2D plane that is commonly used.

Second, we investigate the possibility to obtain density measurements for each varve, allowing calculating annually resolved sediment fluxes in gr cm^-2 a^-1. To achieve this, we µCT-scanned several varved sequences containing sediments covering a wide range of density and extracted their linear attenuation. Then, discrete volumetric samples were subsampled, weighted, gradually dried every 30 minutes and µCT-scanned each time at two different incident energies. This allowed establishing a calibration of water content based on linear attenuation coefficients. Once the density and water content were obtained, the next step was to calculate the density and the mass accumulation rate for each varve.

This approach will pave the way for “forward modelling,” namely the modelling of climate indicators (proxy) contained in natural archives. This method is recognized as a way of improving paleoclimate reconstructions, as it is less sensitive to the non-linearity of the physical processes involved in the formation of proxies than the statistical models that are commonly used.

How to cite: Francus, P. and Jamba, M.-E.: Using micro-computed tomography (µCT) to measure annually resolved sediment fluxes in varved sediments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7319, https://doi.org/10.5194/egusphere-egu25-7319, 2025.

Climate warming is projected to intensify the eutrophication and deoxygenation of lakes globally, exacerbating the already severe consequences for society and ecosystems. Sedimentary archives record the complex interplay between climate, lake mixing, algal production, nutrient dynamics, anoxia and related chemical feedback. However, eutrophication phases could be short-lived, and relevant changes may happen at sub-decadal timescales. Often, eutrophic or anoxic phases are preserved in a few centimetres of sediment and cannot be studied in detail with conventional methods. Imaging techniques aid in investigating eutrophication and deoxygenation in the past by providing continuous, high-resolution and very large data sets for statistical analysis. This study utilises high-resolution techniques — hyperspectral imaging and X-ray fluorescence — to analyse hysteresis behaviour, leads and lags among drivers and responses, and temperature-eutrophication-anoxia relationships in the well-dated Late-Glacial lacustrine sediments of Soppensee (Switzerland). 

Soppensee got eutrophic and developed anoxia during the second half of the Bølling. Phosphorus (P) was efficiently recycled (reductive dissolution) further fuelling eutrophication. Eutrophication lagged warming by 300 years suggesting that warm temperatures were pre-conditional to eutrophication and anoxia while not directly triggering it; Instead, eutrophication responded non-linearly to vegetation dynamics and tree cover around the lake, exhibiting a threshold at 75% tree pollen (TP) and showing hysteresis behaviour. At the onset of eutrophication, the response of anoxia was immediate. Cyanobacteria bloomed with a lead of ~50 years before other phototrophic primary producers, highlighting their potential role as early ecosystem pioneers.

When eutrophication decreased due to landscape opening (TP < 75%) caused by a cold interval (GI1d, Older Dryas), the lake became well-mixed, and P started to become sequestered in sediments, further remediating lake eutrophication. During the warm phases of the Allerød, two more eutrophic and anoxic phases occurred. However, their amplitudes further decreased due to the effective sequestration of P (suppressed chemical feedback). Eutrophication disappeared at the start of the Younger Dryas when the landscape opened, and the lake was well mixed.

This high-resolution study demonstrates the potential of sedimentary imaging techniques to detect short-lived events, rapid regime shifts, leads and lags between forcing and responses in ancient ecosystems.

How to cite: Schouten, S., Zahajská, P., and Grosjean, M.: High-Resolution Insights into Climate-Eutrophication-Anoxia Interactions in Late-Glacial Soppensee , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5809, https://doi.org/10.5194/egusphere-egu25-5809, 2025.

Mg/Ca and δ¹⁸O in foraminiferal shells are the most commonly used paleoclimate proxies for ocean temperature, salinity, and global ice volume. It is hypothesized that preferential dissolution of more soluble shell features and heterogenous shell chemistry as well as recrystallization can alter original shell chemistry as foraminifera sink below the lysocline into the deep ocean to be deposited as sediments. Core top studies have provided valuable insight into this process using closely grouped core tops with similar calcification conditions at the sea surface and different bottom water carbonate chemistry. They have proposed corrections for downcore Mg/Ca and/or δ¹⁸O based paleoclimate records using size normalized shell weights or past carbonate chemistry. However, it is impossible to unequivocally disentangle the effects of original calcification conditions and dissolution on core top shell chemistry at multiple sites. Recent studies have shown that foraminiferal shell dissolution can be simulated through lab-based experiments and dissolution intensity constrained using X-ray microcomputed tomography (Micro-CT) scans of the dissolved shells. We investigated dissolution effects by simulating dissolution of Neogloboquadrina pachyderma, the dominant polar foraminiferal species. Living N. pachyderma were collected from one station in the Greenland Sea via plankton tows and frozen at -80°C prior to dissolution experiments. Aliquots of 200 and 300 picked shells were dissolved in acidified Labrador Sea bottom water on a shaker table for two and three days respectively. An additional 189 shells were kept undissolved as a control. Micro-CT scans show that the average percentage of low-density calcite increased from 33.3 ± 3.6% for the undissolved shells, to 39.2 ± 4.3% for the two-day dissolved shells, to 44.8 ± 6.5% for the three-day dissolved shells, demonstrating an increase in dissolution intensity with an increase in dissolution time. We present δ¹⁸O and solution and LA-ICPMS based Mg/Ca results from the experiments that constrain the impact of dissolution on foraminiferal shell chemistry and propose a new framework for handling dissolution when generating foraminiferal chemistry-based paleoclimate records.

How to cite: Weiss, T., Morley, A., Fabbrini, A., Ninnemann, U., Foster, G., and Brown, R.: Experimental Constraints on the Impact of Shell Dissolution on the Mg/Ca Temperature Relationship in the Polar Foraminifera Species Neogloboquadrina pachyderma, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19047, https://doi.org/10.5194/egusphere-egu25-19047, 2025.