HAW Hamburg

Forest soils play a key role in global carbon (C) storage. Important for long-term C storage in soil is the formation of mineral-associated organic matter (MAOM), which is protected through chemical bonds and occlusion from decomposition. Recent research demonstrated shifts in forest C cycles depending on tree diversity and mycorrhizal type, but we still lack mechanistic knowledge about the role of tree diversity and associated mycorrhizal symbiosis in soil C stabilization.This study aims to quantify particulate organic matter (POM) and MAOM in relation to tree diversity and mycorrhizal type, i.e., ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM) and to investigate the contributions of plant and microbial residues to POM and MAOM. It was conducted in the MyDiv tree experiment (Bad Lauchstädt, Germany), established in 2015 with 10 different deciduous tree species planted across a gradient of species richness. After density separation of POM and MAOM fractions, their mass, carbon and nitrogen (N) contents as well as 13C and 15N isotopic composition were determined. Soil samples were also taken from the grassland next to the site as background values. In addition, we measured 13C and 15N natural abundances of leaf litter, fine roots, saprotrophic and ectomycorrhizal sporocarps as well as ectomycorrhizal and soil hyphae.There was no significant difference in the amount and C content of POM and MAOM between treatments. However, there was a tendency towards more POM (and POM-C) in diverse - especially ECM - systems. Compared to the grassland, C and N contents in POM were lower, which may result from reduced litter input after planting trees (soil was covered with a weed tarp until canopy closure). In line with this, POM of forest soil samples was enriched in 13C and 15N compared to grassland POM, suggesting a higher share of microbial residues in forest POM due to litter exclusion. Interestingly, also C content in MAOM declined due to litter exclusion, whereas 13C in MAOM seemed unaffected by the transition from grassland to forest.The higher C/N ratio of POM compared to MAOM aligned with the expected greater contribution of plant residues to POM and microbial residues to MAOM. This is in accordance with a higher 13C-enrichment of MAOM compared to POM, especially in diverse systems and irrespective of the mycorrhizal type.All in all, the analysis of natural stable isotope abundances is a powerful tool to elucidate the composition of POM and MAOM in temperate forests, which may change depending on forest age, mycorrhizal type and tree diversity.

Ambient seismic noise beamforming tries to identify the direction (traditional one component beamforming) or the direction and wavetype (three component beamforming) of the incoming ambient noise field. If the signal is weak, either taking longer time intervals or stacking several consecutive time windows is employed to obtain a sharper image of the underlying noise sources. However, this also reduces the temporal resolution of the noise sources and might prevent the identification of distinct sources in the case of a temporally highly variable noise field. In addition, the presence of very local, often station specific, noise sources can compromise the coherence of the seismic noise field, preventing the identification of noise sources. The identification and subsequent removal of either time intervals or single stations with exceptionally low signal correlation could thus also lead to an improvement in the temporal resolution of the seismic noise sources and the classification of the ambient seismic noise field.In this study, we investigate the ambient seismic noise field recorded with different temporary short period seismic networks in the Euregio Meuse-Rhine (EMR). The region is a candidate site for the next generation gravitational wave telescope (Einstein telescope) and characterizing the anthropogenic ambient surface noise field with high spatial and temporal variability containing many different noise sources (e.g. highways, railway lines, industry, wind turbines, urban settlements) is essential. We investigate the spatio-temporal coherence of the seismic wavefield to identify time intervals and regions with high waveform coherence which are then investigated for possible ambient noise sources. The one component and three component (when available) beamforming results are compared with results from matched field processing (MFP) to validate that the sources are outside the recording network and to estimate the possible geographic source area.We observe a clear diurnal character of the coherence of the ambient seismic noise field over a wide frequency range from about 2 to 20 Hz with significantly higher coherence values during night. This indicates the prevalence of very local noise contributions during working hours. In addition, a clear anti-correlation between wavefield coherence and wind speed also indicates the local character of wind generated noise. Limiting beamforming analysis to time windows and stations with high coherence improves the beamforming results and the temporal resolution during time intervals identified as coherent. Beamforming results during time intervals with high waveform coherence often show stable backazimuth directions indicating persistent ambient noise sources. The source location outside the recording network is confirmed by the results of the MFP analysis. This also holds for time intervals during working hours and can be confirmed by MFP processing. Results from such investigations might be used as best practices for the spatio-temporal characterization of ambient noise sources in the case of highly complex noise fields.

Engagement of local communities and stakeholders in development of climate change adaptation solutions has become one of the key factors for successful outcomes particularly in developing countries. However, despite various European initiatives focusing on supporting knowledge transfer and collaborative scientific and applied projects, many African countries still face challenges related to ensure sustainability and visibility of impacts. Overcoming these constraints remains a core challenge in developing countries. The more opportunities countries have, the better they are equipped to face climate change and build resilience.The Research and Transfer Centre “Sustainable Development and Climate Change Management (FTZ NK)” has a several decades experience in supporting knowledge technology transfer including training programmes and community engagement as well as fundamental and applied research on climate issues.In this session, we will share key insights and good practices of two key projects of the Centre that illustrate how distinctive collaborative multistakeholder action has contributed effectively to the translation of research results into practical applications and communication of results to communities and stakeholders in the context of climate change impacts and adaptation in Africa are:Project “Green Garden/Jardins adaptés au climat (Towards Climate Resilient Farming/Des jardins partagés et d'adaptation aux changements climatiques)”, jointly funded by the Government of Canada’s New Frontiers in Research Fund (NFRF) and by the Deutsch Forschungsgemienschaft (DFG) brings together 200 vulnerable farmers from seven enterprises in Benin, Morocco, and Canada and 20 researchers representing an interdisciplinary consortium of researchers from Canada, Germany, Morocco, and Benin to co-design and adopt successful climate change adaptation practices in agriculture and agroforestry in collaboration with local communities.Project “RECC-LUM (Feasibility Study on Climate Change, Land Use Management, and Renewable Energy in The Gambia)” funded by BMFTR and supported by The Gambia Ministry of Higher Education, Research, Science, and Technology (MoHERST) focuses on sustainable land management practices within the Gambian agricultural landscape and the role played by using renewable energy in the process with active engagement of local farmers. Besides co-creation and collaborative learning with local stakeholders and strong international cooperation and visibility, one of the key components of the project is continuous and strong communication of results to stakeholders and policy makers.

Der Beitrag wirft Schlaglichter auf die Entstehungsgeschichte der Kindheitspädagogik als Profession mit eigenem Bachelorstudiengang sowie die Etablierung der Kindheitspädagogik innerhalb der Kinder- und Jugendarbeit. Ergänzend werden aktuelle Daten zur beruflichen Positionierung von Kindheitspädagog*innen auf dem Arbeitsmarkt vorgestellt und die damit verbundenen Herausforderungen analysiert.

ABSTRACT The banking sector plays a critical role in fostering sustainability by directing capital toward environmentally and socially responsible projects. Yet, there is a perceived need for studies that shed some light on their activities in this field. This Communication sheds some light on the contribution of the banking sector to support the development of small organizations toward SDG 9.

Alkaline feedstocks for ocean alkalinity enhancement (OAE) must guarantee efficient alkalinity release while having limited impact on marine ecosystems and carbonate mineral saturation levels (Ω CaCO3 ). When considering mineral powder addition as a deployment option, currently considered feedstocks either exhibit slow dissolution kinetics or may require additional water treatment to limit rapid pH changes. Carbonate minerals, on the other hand, feature fast dissolution when undersaturated, accompanied with a reduced impact on pH and Ω CaCO3 . However, traditional (non-hydrated) carbonate minerals such as calcite and aragonite are insoluble in seawater and therefore impractical as direct-to-use feedstocks for OAE. Here, we examine the dissolution kinetics and alkalinity release efficiency of ikaite (CaCO 3 ·6H 2 O) — a hydrated carbonate mineral producible from limestone and dissolvable in seawater — across a range of global sea surface temperatures through a series of controlled laboratory-scale experiments. The main focus lay on determining the alkalinity release efficiency at temperatures where ikaite usually becomes thermodynamically unstable (> 6° C). The conducted experiments showed that ikaite dissolved at temperatures of 10 – 26 °C with initial dissolution rates comparable to calcite at highly undersaturated conditions (7.62 x 10 -6 - 2.17 x 10 -5 mol m -2 s -1 ) but exhibited a limited alkalinity release efficiency (50 – 80 % of potential alkalinity added). The reduced alkalinity release was likely caused by partial transformation of ikaite into non-soluble carbonate minerals before complete alkalinity release could be reached. An additional experiment at 3 °C resulted in a higher alkalinity release efficiency (85 – 100 %) but was accompanied by a two magnitudes lower initial dissolution rate (1.43 – 1.63 x 10 -7 mol m -2 s -1 ) revealing a tradeoff between the dissolution rate and alkalinity release efficiency as a function of temperature. The results emphasize that efficient ikaite dissolution is limited to cold waters (< 10 °C). It also stresses that when rates vary with the environmental conditions they must comply with suitable particle size distributions to maintain sinking rates and effective CO 2 uptake. Therefore, we integrated derived dissolution rates and alkalinity release efficiencies together with different practical particle size distributions into a non-turbulent stokes formulation. The model output suggests that in warmer seawater (> 10 °C) the alkalinity disperses within 10 m below the sea surface, but due to reduced alkalinity release efficiency, CO 2 would be lowered to ∼0.7 – 1.3 mole per mole of added Ca 2+ . At 3 °C, on the other hand, the CO 2 uptake efficiency is less affected by incomplete dissolution of ikaite but likely varies more with mean particle size, emphasizing its critical role in cold waters. It remains to be tested whether these results also apply on a larger scale, for example by conducting tank or mesocosm experiments. • Ikaite dissolves fast in seawater over a wide temperature gradient • addition of ikaite to seawater likely comes with a reduced alkalinity release efficiency at water temperatures above 10 °C • Particle size distributions with a mean size <100 μm facilitate releasing major fractions of alkalinity within the ocean mixed layer which constitute CO 2 uptake

The growing integration of intermittent renewables, especially solar PV, challenges grid stability and limits the operational flexibility of conventional hydropower. Beyond hydrological variability, hydropower is constrained by mandatory ecological flow releases, which restrict its ability to reduce generation during high solar output or ramp up during peak demand due to water scarcity. This paper introduces Ecological Flow Energy Storage (EFES), a cost-effective, environmentally sound solution to enhance grid flexibility. EFES involves building small reservoirs downstream of existing hydropower plants to temporarily store ecological flows. This decouples ecological requirements from electricity generation, enabling hydropower plants to halt generation during solar-rich periods without breaching environmental mandates. Stored water can later be released through upstream turbines during low solar availability or peak demand, effectively turning a regulatory constraint into a strategic energy storage asset. EFES supports better integration of renewables, optimizes hydropower dispatch, and enables economic arbitrage, all while preserving downstream ecological services. In Brazil, the estimated EFES potential is 14.3 GW, with a storage cost that can be ten times lower than battery storage. This paper explores the technical feasibility, economic viability, and environmental implications of EFES, highlighting its promise as a scalable, low-cost energy storage solution for modern power systems. • A proposal for increasing the flexibility of hydropower for both ecological and energy services • Downstream micro-reservoirs can decouple hydropower generation from ecological flow. • Enabling hydropeaking to reduce solar curtailment • In Brazil, Ecological Flow Energy Storage can shave ∼14.3 GW peak. • A scalable, low-cost path to integrate VRE via hydropower flexibility

Helminths infect a quarter of the human population and are controlled in the frame of a canonical type-2 immune response. Interleukin-9 is a cytokine with pleiotropic functions during type-2 immunity that can be produced by many different cells. Accumulating evidence suggest that IL-9 is of particular relevance in controlling intestinal helminth infections. Using mice infected with the parasitic nematode Strongyloides ratti, we showed previously that ejection from the intestine depends on IL-9 and IL-9-mediated activation of mucosal mast cells. Here we use IL-9 reporter mice to identify the relevant cellular sources of IL-9 in vivo. We report that predominantly CD4+ T cells and group 2 innate lymphoid cells (ILC2s) produced IL-9 in S. ratti-infected or IL-33-treated mice. Interestingly, the IL-33-mediated induction of IL-9 and subsequent mast cell degranulation was modulated by concurrent S. ratti infection. While the IL-33-mediated expansion of IL-9-producing ILC2s was supressed by S. ratti infection, IL-9-producing CD4+ T cells were proportionally increased. Finally, we show that S. ratti-derived E/S products interfered with IL-9 production by BM-derived ILC2 in vitro. In conclusion, we have identified that ILC2 and CD4+ T cells produce IL-9 during S. ratti infection, and that ILC2 responses are suppressed by S. ratti products.