This dataset contains C. wuellerstorfi stable carbon isotope values binned by marine isotope stage from ODP Site 162-807 and ODP Site 162-982 that span the last 4.5 million years (Feng et al. 2022; Venz et al. 1999, 2002; Hodell & Venz-Curtis 2006). This isotope gradient reflects the accumulation of respired and disequilibrium carbon in the deep Pacific ocean relative to the North Atlantic. Also included are binned probstack δ18O (Ahn et al., 2017) and ΔGMST (Clark et al., 2024) values for comparison to the binned stable carbon isotope values.
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.
This dataset contains geochemical variables measured in six depth profiles from ombrotrophic peatlands in North and Central Europe. Peat cores were taken during the spring and summer of 2022 from Amtsvenn (AV1), Germany; Drebbersches Moor (DM1), Germany; Fochteloër Veen (FV1), the Netherlands; Bagno Kusowo (KR1), Poland; Pichlmaier Moor (PI1), Austria and Pürgschachen Moor (PM1), Austria. The cores AV1, DM1 and KR1 were taken using a Wardenaar sampler (Royal Eijkelkamp, Giesbeek, the Netherlands) and had diameter of 10 cm. The cores FV1, PM1 and PI1 had an 8 cm diameter and were obtained using an Instorf sampler (Royal Eijkelkamp, Giesbeek, the Netherlands). The cores FV1, DM1 and KR1 were 100 cm, core AV1 was 95 cm, core PI1 was 85 cm and core PM1 was 200 cm. The cores were subsampeled in 1 cm (AV1, DM1, KR1, FV1) and 2 cm (PI1, PM1) sections. The subsamples were milled after freeze drying in a ballmill using tungen carbide accesoires. X-Ray Fluorescence (WD-XRF; ZSX Primus II, Rigaku, Tokyo, Japan) was used to determine Al (μg g-1), As (μg g-1), Ba (μg g-1), Br (μg g-1), Ca (g g-1), Cl (μg g-1), Cr (μg g-1), Cu (μg g-1), Fe (g g-1), K (g g-1), Mg (μg g-1), Mn (μg g-1), Na (μg g-1), P (μg g-1), Pb (μg g-1), Rb (μg g-1), S (μg g-1), Si (μg g-1), Sr (μg g-1), Ti (μg g-1) and Zn (μg g-1). These data were processed and calibrated using the iloekxrf package (Teickner & Knorr, 2024) in R. C, N and their stable isotopes were determined using an elemental analyser linked to an isotope ratio mass spectrometer (EA-3000, Eurovector, Pavia, Italy & Nu Horizon, Nu Instruments, Wrexham, UK). C and N were given in units g g-1 and stable isotopes were given as δ13C and δ15N for stable isotopes of C and N, respectively. Raw data C, N and stable isotope data were calibrated with certified standard and blank effects were corrected with the ilokeirms package (Teickner & Knorr, 2024). Using Fourier Transform Mid-Infrared Spectroscopy (FT-MIR) (Agilent Cary 670 FTIR spectromter, Agilent Technologies, Santa Clara, Ca, USA) humification indices (HI) were determined. Spectra were recorded from 600 cm-1 to 4000 cm-1 with a resolution of 2 cm-1 and baselines corrected with the ir package (Teickner, 2025) to estimate relative peack heights. The HI (no unit) for each sample was calculated by taking the ratio of intensities at 1630 cm-1 to the intensities at 1090 cm-1. Bulk densities (g cm-3) were estimated from FT-MIR data (Teickner et al., in preparation).
Globally, agriculture covers 40% of the earth’s surface and food systems are responsible for one-third of humanity’s contribution to global climate change. Yet, smallholder and subsistence farmers are among the most vulnerable to climate change, with extreme weather events and related food price volatility affecting livelihoods, biodiversity, and food security at multiple scales. This project builds on transdisciplinary research on agroecological transitions in vulnerable farming communities in Canada, Germany, India and Brazil. We will examine the influence of agroecological networks (farming organizations, institutional actors, and consumer groups) in promoting the perennialization of agriculture to support climate adaptation (improving resilience in livelihoods and food security) and mitigation (increasing carbon sequestration). Perennialization of agriculture integrates annual and perennial crops and trees into the same farming system. Compared to annual cropping systems which currently dominate global agriculture and markets, perennial crops show promise for climate adaptation and mitigation because of their contributions to carbon sequestration in tree biomass and soil organic carbon, and their buffering effects against soil degradation, drought, and other forms of extreme weather and climate variability. From a social wellbeing perspective, agroforestry and other diversified perennial systems offer opportunities to adapt to climate change and escape poverty traps, including higher and more stable farm incomes, balanced agricultural labour across growing seasons, improved working conditions compared to more input-intensive forms of agriculture and improved nutrition and health. Using a participatory action research approach, this project will use a novel methodology to test the relationships between personal, political, and practical leverage points driving the adoption of agroforestry and other practices supporting agricultural perennialization. We will sample farms and organizations in each case study across a diversification gradient from low-diversity farming systems to perennial and agroforestry-based management systems. We will then use qualitative and quantitative methods to assess climate resilience outcomes and estimate the potential of scaling adoption of perennial and agroforestry practices. A cross-case synthesis will take local institutional, environmental, and relational contexts into account to inform decision-making.
Recent and predicted increases in extremely dry and hot summers emphasise the need for silvicultural approaches to increase the drought tolerance of existing forests in the short-term, before adaptation through species changes may be possible. We aim to investigate whether resistance during droughts, as well as the recovery following drought events (resilience), can be increased by allocating more growing space to individual trees through thinning. Thinning increases access of promoted trees to soil stored water, as long as this is available. However, these trees may also be disadvantaged through a higher transpirational surface, or the increased neighbourhood competition by ground vegetation. To assess whether trees with different growing space differ in drought tolerance, tree discs and cores from thinning experiments of Pinus sylvestris and Pseudotsuga menziesii stands will be used to examine transpirational stress and growth reduction during previous droughts as well as their subsequent recovery. Dendroecology and stable isotopes of carbon and oxygen in tree-rings will be used to quantify how assimilation rate and stomatal conductance were altered through thinning. The results will provide crucial information for the development of short-term silvicultural adaptation strategies to adapt forest ecosystems to climate change. In addition, this study will improve our understanding of the relationship between resistance and resilience of trees in relation to extreme stress events.
Water is an intrinsic component of ecosystems acting as a key agent of lateral transport for particulate and dissolved nutrients, forcing energy transfers, triggering erosion, and driving biodiversity patterns. Given the drastic impact of land use and climate change on any of these components and the vulnerability of Ecuadorian ecosystems with regard to this global change, indicators are required that not merely describe the structural condition of ecosystems, but rather capture the functional relations and processes. This project aims at investigating a set of such functional indicators from the fields of hydrology and biogeochemistry. In particular we will investigate (1) flow regime and timing, (2) nutrient cycling and flux rates, and (3) sediment fluxes as likely indicators. For assessing flow regime and timing we will concentrate on studying stable water isotopes to estimate mean transit time distributions that are likely to be impacted by changes in rainfall patterns and land use. Hysteresis loops of nitrate concentrations and calculated flux rates will be used as functional indicators for nutrient fluxes, most likely to be altered by changes in temperature as well as by land use and management. Finally, sediment fluxes will be measured to indicate surface runoff contribution to total discharge, mainly influenced by intensity of rainfall as well as land use. Monitoring of (1) will be based on intensive sampling campaigns of stable water isotopes in stream water and precipitation, while for (2) and (3) we plan to install automatic, high temporal-resolution field analytical instruments. Based on the data obtained by this intensive, bust cost effective monitoring, we will develop the functional indicators. This also provides a solid database for process-based model development. Models that are able to simulate these indicators are needed to enable projections into the future and to investigate the resilience of Ecuadorian landscape to global change. For the intended model set up we will couple the Catchment Modeling Framework, the biogeochemical LandscapeDNDC model and semi-empirical models for aquatic diversity. Global change scenarios will then be analyzed to capture the likely reaction of functional indicators. Finally, we will contribute to the written guidelines for developing a comprehensive monitoring program for biodiversity and ecosystem functions. Right from the beginning we will cooperate with four SENESCYT companion projects and three local non-university partners to ensure that the developed monitoring program will be appreciated by locals and stakeholders. Monitoring and modelling will focus on all three research areas in the Páramo (Cajas National Park), the dry forest (Reserva Laipuna) and the tropical montane cloud forest (Reserva Biologica San Francisco).
Time series of stable isotopes (δ2H and δ18O) were analyzed in water samples collected near the A. P. Møller Skolen, Schleswig (Kleine Breite, Schlei), in biweekly to monthly intervals between March 2020 and March 2021. Water was sampled with a pipette from ca. 0.5 m below water surface and directly transferred into a measurement vial. 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 modular WTW 3440 multiparameter devices and regularly calibrated conductivity cells (MPP 930 IDS, TetraCon® 925-P). The data give information about the seasonal isotope amplitude at the sampled locations and about spatial variability along the transects.
Water isotopes (δ²H and δ¹⁸O) were analyzed in samples from lakes and rivers in eastern Germany. This sub-dataset is derived from water samples collected from lake and river shores. Seasonal samples were collected in March, July, October 2022, and in March 2023, with a plastic syringe from 20-50 cm depth below water surface and directly filtered and transferred into a measurement vial. Stable isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Measurement uncertainty was quantified to <0.5 ‰ for δ²H and <0.2 ‰ for δ¹⁸O. Water chemical parameters were determined in-situ with a portable WTW-multiparameter probe. The data give information about the seasonal isotope amplitude at the sampled spots and about spatial isotope variability in different branches of the associated river systems.
Time series of stable isotopes (δ2H and δ18O) were analyzed in water samples taken near the harbour of Kloster (Hiddensee), in biweekly to monthly intervals between March 2020 and March 2021. Water was sampled with a pipette from ca. 0.5 m below water surface and directly transferred into a measurement vial. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water chemical parameters were measured in-situ with WTW multiparameter measurement devices. The data give information about the seasonal isotope amplitude at the sampled locations and about spatial variability along the transects.
Time series of stable isotopes (δ2H and δ18O) were analyzed in water samples collected at the Zingster Bodden chain in biweekly to monthly intervals between March 2020 and March 2021. Herefore, a Limnos sampler was used to obtain water from 0.5 to 1 m below surface. In the laboratory, a WTW 1970i conductivity meter and TetraCon 325 measuring cell were used to analyse electrical conductivity. Sub-samples were transferred into measurement vials before isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water chemical parameters were measured with regularly calibrated WTW multiparameter devices. The data give information about the seasonal isotope amplitude at the sampled locations and about spatial variability along the transects.
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