ALBERT

Description: Striving to mitigate climate change, the European Union has adopted net-zero greenhouse gas emissions as a target for 2050. In this paper, European chemical industry roadmaps from the past six years are assessed and compared to uncover how the industry envisions its role in the transition to net-zero emissions. The roadmaps are assessed in terms of ambition level, technology and feedstock strategies, investment needs and costs, agency and dependency on other actors, as well as timeline and concretion. Although net-zero pathways are often drawn out in the roadmaps, some also choose to emphasize and argue for less ambitious pathways with emission reductions of only 40-60 %. The roadmaps vary widely in terms of the importance they assign to mechanical and chemical recycling, switching to biogenic carbon and carbon dioxide as feedstock, electrification and hydrogen, and carbon capture and storage. A commonality though, is that low-tech or near-term mitigation pathways such as demand reduction, reuse or material efficiency are seldom included. High investment needs are generally highlighted, as well as the need for policy to create enabling conditions, whereas the agency and responsibility of the chemical industry itself is downplayed. Our analysis highlights that the chemical industry does not yet have a strong and shared vision for pathways to net-zero emissions. We conclude that such a future vision would benefit from taking a whole value chain approach including demand-side options and consideration of scope 3 emissions.

Description: A clear understanding of socio-technical interdependencies and a structured vision are prerequisites for fostering and steering a transition to a fully renewables-based energy system. To facilitate such understanding, a phase model for the renewable energy (RE) transition in MENA countries has been developed and applied to the country case of Morocco. It is designed to support the strategy development and governance of the energy transition and to serve as a guide for decision makers. Such a phase model could be shared widely as part of Morocco's engagement in international platforms of multilateral collaboration, such as the Energy Transition Council (chaired by the United Kingdom (UK) and managed by the British Embassy - Rabat). The analysis shows that Morocco has fully embarked on the energy transition. According to the MENA phase model, Morocco can be classified as being in the second phase "System Integration of Renewables". Nevertheless, Morocco plans to considerably increase the use of natural gas in order to back up intermittent solar and wind energy sources. The diversification of energy sources and a diverse portfolio of storage options, including solar thermal power and hydrogen, can foster flexibility options. To this end, a roadmap for power-to-X (PtX) should be considered for a smooth transition of the Moroccan energy supply and demand system. The expansion of local REs can significantly contribute to reducing Morocco's high fossil fuel imports that are causing a high fiscal burden. With this regard, energy security can be strengthened. Next to large-scale deployment, decentralisation of the energy system must be built to encourage an energy transition on all societal levels. The results of the analysis along the transition phase model towards 100% RE are intended to stimulate and support the discussion on Morocco's future energy system by providing an overarching guiding vision for energy transition and the development of appropriate policies.

Description: Green hydrogen and synthetic fuels are increasingly recognized as a key strategic element for the progress of the global energy transition. The Middle East and North Africa (MENA) region, with its large wind and solar potential, is well positioned to generate renewable energy at low cost for the production of green hydrogen and synthetic fuels, and is therefore considered as a potential future producer and exporter. Yet, while solar and wind energy potentials are essential, other factors are expected to play an equally important role for the development of green hydrogen and synthetic fuels (export) sectors. This includes, in particular, adequate industrial capacities and infrastructures. These preconditions vary from country to country, and while they have been often mentioned in the discussion on green hydrogen exports, they have only been examined to a limited extent. This paper employs a case study approach to assess the existing infrastructural and industrial conditions in Jordan, Morocco, and Oman for the development of a green hydrogen and downstream synthetic fuel (export) sector.

Description: Das Bundesministerium für Wissenschaft und Klimaschutz (BMWK) möchte innovationsfreundliche Rahmenbedingungen für Reallabore schaffen. Im Sommer 2023 hat es dazu ein Grünbuch Reallabore veröffentlicht und einen Konsultationsprozess für ein Reallabore-Gesetz eingeleitet. Das Netzwerk Reallabore der Nachhaltigkeit begrüßt die Initiative, sieht aber zugleich erheblichen Gestaltungsbedarf. Die NaWis-Mitglieder unterstützen die hier vorgestellte Position des Netzwerks.

Description: Für die Landesregierung Nordrhein-Westfalen (NRW) ist die industriell genutzte Kohlenstoffabscheidung und -speicherung (engl. industrial carbon capture and storage, kurz iCCS) ein zentraler Baustein für den Übergang zu einer klimaneutralen Industrie bis 2045. Dafür braucht es aber eine breite gesellschaftliche Akzeptanz - zumal Pläne zur CO2-Abscheidung bei Kohlekraftwerken vor über zehn Jahren schon einmal an mangelnder gesellschaftlicher Akzeptanz gescheitert sind. In diesem In Brief haben die Autor*innen die Ergebnisse von zwei durchgeführten Akzeptanzstudien zu iCCS in NRW zusammengefasst und diskutieren, welche Handlungsempfehlungen sich daraus ergeben.

Description: Nordrhein-Westfalen (NRW) ist Heimat energieintensiver Industrien wie der Stahl- und Chemieindustrie. Künftig wird grüner Wasserstoff notwendig sein, damit die Industrie in NRW Klimaneutralität erreichen kann. Die Herausforderungen hierbei sind jedoch vielfältig - auch wenn die Akzeptanz für grünen Wasserstoff sowohl in der Gesellschaft als auch bei unmittelbar beteiligten Akteursgruppen hoch ist. Die Autor*innen fassen in diesem In Brief die Ergebnisse von zwei durchgeführten Akzeptanzstudien zu grünem Wasserstoff in NRW zusammen und diskutieren, welche Handlungsempfehlungen sich daraus ergeben.

Description: Dieses Buch bietet einen Leitfaden für mehr Klimaschutz an Schulen und holt Schulleitungen, Lehrkräfte und Schüler:innen gemeinschaftlich ins Boot - denn Klimaschutz ist eine Gemeinschaftsaufgabe. Mit dem "Whole School Approach" wird die ganzheitliche Umsetzung von Klimaschutzaktivitäten in der Schulentwicklung angestoßen und auf schulischer Ebene ermöglicht und erleichtert. Ziel ist es, Lehrer:innen in ihrer Gestaltungskompetenz für mehr Klimaschutz zu stärken - dies geschieht durch konkrete Vorschläge für die Arbeit mit Schüler:innen im Unterricht. Partizipative Methoden der Beteiligung sollen die Schüler:innen empowern und den Lehrkräften Ideen geben, um die eigene Selbstwirksamkeit, aber auch die der Schüler:innen zu steigern. Die zentrale Kernbotschaft lautet: ein Klimaschutzprojekt an der Schule ist wesentlich für die strukturelle Verankerung von Bildung für nachhaltige Entwicklung im Schulalltag. Der Leitfaden gibt Anregungen für die Unterrichtsgestaltung, Anregungen für die Entwicklung eines Klimaschutzleitbildes, Hinweise für das Gebäudemanagement und Ideen zur Einbindung des schulischen Umfelds.

Description: Innovative Finanzierungskonzepte wie Solar und Spar-Bürgercontracting belegen, dass ein riesiges Einsparpotenzial an Schulen wirtschaftlich erschlossen werden könnte. Doch bislang passiert zu wenig, um dieses auch zu nutzen. ­Das Projekt Schools4Future zeigt, wie Schulen eigenständig eine CO2-Bilanz erstellen können, um nicht nur eigene Klimaschutzmaßnahmen umzusetzen, sondern auch, um der Politik zu zeigen, wo dringender Handlungsbedarf besteht.

Description: Städte und damit auch ihre Straßen wurden in den vergangenen Jahrzehnten stark nach dem Leitbild einer autogerechten Stadt geplant. Heute besteht ein weitgehender Konsens darüber, dass sich Städte bzw. Straßen wandeln müssen, um sich an die Folgen des Klimawandels anzupassen, und dass die Verkehrswende nur mit angepassten städtischen Verkehrsinfrastrukturen, die aktive Mobilitätsformen fördern, gelingen kann. Dennoch kommt es bei konkreten Projekten vor Ort häufig zu gesellschaftlichen und politischen Widerständen. Vor diesem Hintergrund beschreibt dieser Beitrag einen dreistufigen kollaborativen Beteiligungs- und Planungsprozess mit der Zivilgesellschaft, der Stadtverwaltung und der Kommunalpolitik für den Umbau einer Quartiersstraße in Dortmund. Ziel des Prozesses war es, die Zieldimensionen Verkehrswende, Aufenthaltsqualität und Klimaresilienz (blau-grüne Infrastrukturen) integriert zu betrachten, um eine gleichermaßen ambitionierte wie gesellschaftlich tragfähige Planung zu entwickeln. Der Beitrag beschreibt die empirischen Arbeiten und Befunde, stellt dar, wie die Rückmeldungen aus dem Beteiligungs- und Planungsprozess in die Planungsentwürfe integriert wurden, und reflektiert den Einsatz von Visualisierungen und Straßenexperimenten als Instrumente für eine kollaborative Planung.

Description: This paper presents a novel governance concept for sustainable development, introducing the "Safe System Approach" as a transformative model that shifts focus from individual behavioural change to systemic transformation. This approach challenges traditional governance models that emphasize individual responsibility in achieving sustainable development and decarbonization. Instead, it advocates for creating an enabling environment that inherently guides individuals and communities towards sustainable actions. The Safe System Approach is centred on delivering low-carbon services across essential sectors, including electricity, mobility, industry, buildings, human settlements, and agriculture, thereby embedding sustainability as a default choice in societal systems. Drawing parallels with successful models in road safety, the paper explores the potential of this approach in urban development and climate action. It emphasizes the need for a broad coalition and integrated approaches in managing shared resources, highlighting the significance of systemic adjustments over individual behavioral change. By proposing a structure where sustainability is facilitated by the system's design, the paper builds on key concepts from seminal works by scholars like Garrett Hardin, Mancur Olson, Elinor Ostrom, and Ahrend Lijphart. It discusses the challenges and opportunities in creating safe operating spaces for sustainable development, emphasizing the need for multi-actor, multilevel governance systems that can manage shared resources sustainably and are resilient to political volatility. The paper aims to offer a robust, efficient, and inclusive pathway to sustainable development, contributing to the global discourse on environmental and social resilience.

Description: Angesichts von Extremwetterereignissen, Klimaprognosen und Bewegungen wie Fridays for Future lässt sich schwer leugnen, dass ein Teil der Menschheit auf eine Weise lebt, die eine gut bewohnbare Welt höchst unwahrscheinlich macht. Städten wird in dieser Situation eine zentrale Rolle zugeschrieben. Sie können die Welt vor der Erderwärmung retten - oder sie sind die Ersten, die untergehen. Doch was genau wird getan, um Städte in Richtung Nachhaltigkeit zu transformieren? Britta Acksel nimmt Aktionspläne, Klimafestivals, Awards und weitere Transformationsinstrumente in den Blick. Ethnographisch fundiert zeigt sie auf, wie sich die Arbeit mit dieser speziellen Form von Policy-Werkzeugen gestaltet - und welche Bemühungen besonders aussichtsreich erscheinen.

Description: Ways of evaluating the societal impact of real-world labs as a transdisciplinary and transformative research format are under discussion. We present an evaluation approach rooted in structuration theory, with a focus on structure-agency dynamics at the science-society interface. We applied the theory with its four modalities (interpretation schemes, norms, allocative and authoritative resources) to the case of the Mirke neighbourhood in Wuppertal, Germany. Six projects promoted the capacity for co-productive city-making. The effects of the projects were jointly analysed in a co-evaluation process. Previously proposed subcategories of the modalities as an empirical operationalisation were tested and confirmed as being applicable. Five new subcategories were generated. The use of the modalities seems appropriate for co-evaluation processes. The tool is practical, focused on real-world effects, and suitable for transdisciplinary interpretation processes. We encourage further empirical testing of the tool, as well as development of the subcategories.

Description: Real-world laboratories (RwLs) are gaining further traction as a means to achieve systemic impacts towards sustainability transformation. To guide the analysis of intended impacts, we introduce the concept of leverage points, discerning where, how, and to what end RwLs intervene in systems. Building on conceptual reasoning, we further develop our argument by exploring two RwL cases. Examining RwLs through the lens of the leverage points opens the way for a balanced and comprehensive approach to systemic experimentation. We invite RwL researchers and practitioners to further advance RwLs' transformative capacity by targeting the design and emerging direction of a system, contributing to a culture of sustainability.

Description: Für Deutschland und viele Industrieländer weltweit wird der Import von grünem Wasserstoff ein zentraler Baustein auf dem Weg zur Klimaneutralität sein. Dabei muss einerseits gewährleistet sein, dass grüner Wasserstoff auch wirklich "grün" im Sinne von klimaneutral ist. Zugleich gibt es immer mehr Forderungen, dass auch andere Nachhaltigkeitskriterien - soziale, ökonomische und ökologische - bei der Produktion und dem Transport von Wasserstoff eingehalten werden. Der politisch getriebene Aufbau einer globalen Wasserstoffwirtschaft bietet von Anfang an die Möglichkeit, diesen Sektor in Einklang mit den bestehenden politischen Zielen zu bringen. Dazu zählen beispielsweise die Pariser Klimaziele oder die Agenda 2030. Die Industrienation Deutschland, die auch in Zukunft auf Energieimporte angewiesen sein wird, kann hier als führende Industrienation als Vorreiter Einfluss nehmen. Damit kann nicht nur sichergestellt werden, dass der nach Deutschland importierte Wasserstoff "grün und nachhaltig" ist, sondern auch die Nachhaltigkeit des globalen Wasserstoffmarktes insgesamt beeinflusst werden. Diese Kurzstudie untersucht, welche bereits existierenden Politikinstrumente geeignet sind, Nachhaltigkeitskriterien für Wasserstoffimporte zu verankern und im Zusammenspiel den Weg zu einem nachhaltigen globalen Wasserstoffmarkt zu unterstützen. Dabei werden ausschließlich Nachhaltigkeitsziele und -kriterien jenseits der Klimawirkung von Wasserstoff analysiert. Es ist unbestritten, dass das zentrale Ziel der Wasserstoffwirtschaft die Reduktion von Treibhausgasen bis hin zur Klimaneutralität ist, was bereits in einer Vielzahl von Studien und Stellungnahmen diskutiert wurde. Daher wird in dieser Studie von der Klimaneutralität des grünen Wasserstoffs ausgegangen, um den Fokus auf die anderen wesentlichen Nachhaltigkeitsaspekte zu lenken, die für den Import von grünem und nachhaltigen Wasserstoff aus dem Globalen Süden von entscheidender Bedeutung sind.

Description: Die schnelle und umfassende Emissionsminderung in der Energie- und Kreislaufwirtschaft ist der Schlüssel für die Begrenzung der Erderwärmung auf unter 2 °C. In Deutschland werden entsprechende Politiken seit den 1990er-Jahren verfolgt, allerdings erst in jüngster Vergangenheit mit dem notwendigen Nachdruck und der notwendigen Orientierung hin zu mehr Marktmechanismen. Wesentliche Handlungsfelder sind Energieeinsparung und erhöhte Energieeffizienz, Umstieg auf erneuerbare Energien, Bepreisung von Klimagasen sowie eine Reduzierung und Schließung der Stoffkreisläufe. In allen Handlungsfeldern sind Grundlagen geschaffen, es bleibt jedoch der Großteil des Weges noch zu gehen, um Klimaneutralität zu erreichen. Für einen schnellen Fortschritt spielen neben der Überwindung der technischen, ökonomischen und organisatorischen Herausforderungen auch Verteilungsfragen und die Einbettung in internationale Maßnahmen eine zunehmende Rolle.

Description: This paper examines the current and prospective greenhouse gas (GHG) emissions of e-fuels produced via electrolysis and Fischer-Tropsch synthesis (FTS) for the years 2021, 2030, and 2050 for use in Germany. The GHG emissions are determined by a scenario approach as a combination of a literature-based top-down and bottom-up approach. Considered process steps are the provision of feedstocks, electrolysis (via solid oxide co-electrolysis; SOEC), synthesis (via Fischer-Tropsch synthesis; FTS), e-crude refining, eventual transport to, and use in Germany. The results indicate that the current GHG emissions for e-fuel production in the exemplary export countries Saudi Arabia and Chile are above those of conventional fuels. Scenarios for the production in Germany lead to current GHG emissions of 2.78-3.47 kgCO2-eq/L e-fuel in 2021 as the reference year and 0.064-0.082 kgCO2-eq/L e-fuel in 2050. With a share of 58-96%, according to the respective scenario, the electrolysis is the main determinant of the GHG emissions in the production process. The use of additional renewable energy during the production process in combination with direct air capture (DAC) are the main leverages to reduce GHG emissions.

Description: Direct air capture (DAC) combined with subsequent storage (DACCS) is discussed as one promising carbon dioxide removal option. The aim of this paper is to analyse and comparatively classify the resource consumption (land use, renewable energy and water) and costs of possible DAC implementation pathways for Germany. The paths are based on a selected, existing climate neutrality scenario that requires the removal of 20 Mt of carbon dioxide (CO2) per year by DACCS from 2045. The analysis focuses on the so-called "low-temperature" DAC process, which might be more advantageous for Germany than the "high-temperature" one. In four case studies, we examine potential sites in northern, central and southern Germany, thereby using the most suitable renewable energies for electricity and heat generation. We show that the deployment of DAC results in large-scale land use and high energy needs. The land use in the range of 167-353 km2 results mainly from the area required for renewable energy generation. The total electrical energy demand of 14.4 TWh per year, of which 46% is needed to operate heat pumps to supply the heat demand of the DAC process, corresponds to around 1.4% of Germany's envisaged electricity demand in 2045. 20 Mt of water are provided yearly, corresponding to 40% of the city of Cologne's water demand (1.1 million inhabitants). The capture of CO2 (DAC) incurs levelised costs of 125-138 EUR per tonne of CO2, whereby the provision of the required energy via photovoltaics in southern Germany represents the lowest value of the four case studies. This does not include the costs associated with balancing its volatility. Taking into account transporting the CO2 via pipeline to the port of Wilhelmshaven, followed by transporting and sequestering the CO2 in geological storage sites in the Norwegian North Sea (DACCS), the levelised costs increase to 161-176 EUR/tCO2. Due to the longer transport distances from southern and central Germany, a northern German site using wind turbines would be the most favourable.

Description: The establishment of the Leveraging a Climate-neutral Society–strategic Research Network (LCS–RNet) (then named the International Research Network for Low Carbon Societies) was proposed at the Group of Eight (G8) Environment Ministers’ Meeting in 2008. Its 12th annual meeting in December 2021 focused on the discussion on how to transition into a just and sustainable society and how to reduce the risks associated with the transition. This requires comprehensive studies including on the concept of transition, pathways to net-zero societies and how to realise the pathways by collaborating with various stakeholders. This Special Feature provides new insights into sustainability science by linking the scientific knowledge with practical science for the transition through the exploration of studies presented at the annual meeting. Following the opening paper, "A challenge for sustainability science: can we halt climate change?", a wide range of topics were discussed, including practices for sustainable transformation in the Erasmus University, practices in industry, energy transition and international cooperation.

Description: Deutschlands Haushalte werden, zu Beheizungszwecken, zu 70 % leitungsgebunden versorgt: 50 % mit Erdgas und 14 % mit Fernwärme; 5 % mit Elektrizität, davon je die Hälfte noch mit Nachtspeicherheizung, die andere Hälfte mit Wärmepumpen. So war es 2021. So wird es in Zukunft nicht sein, denn Erdgas ist ein Energieträger fossiler Herkunft. Dessen Nutzung geht in den nächsten beiden Jahrzehnten gen Null. Die Frage ist, was das für die Erdgasleitungen in Deutschland bedeutet.

Description: The petrochemical industry is among the most relevant sectors from an economic, energetic and climate policy perspective. In Western Europe, production occurs in local chemical parks that form strongly connected and densely integrated regional clusters. This paper analyzes the structural characteristics of the petrochemical system in Germany and investigates three particularly distinct clusters regarding their challenges and chances for a transition towards climate-neutrality. For this, feedstock and energy supply, product portfolios and process integration as well as existing transformation activities are examined. We find that depending on their distinct network characteristics and location, unique and complex strategies are to be mastered for every cluster. Despite the many activities underway, none of them seems to have a strategic network to co-create a tailored defossilization strategy for the cluster - which is the core recommendation of this paper to develop.

Description: Demand-side mitigation strategies have been gaining momentum in climate change mitigation research. Still, the impact of different approaches in passenger transport, one of the largest energy demand sectors, remains unclear. We couple a transport simulation model to an energy system optimisation model, both highly disintegrated in order to compare those impacts. Our scenarios are created for the case of Germany in an interdisciplinary, qualitative-quantitative research design, going beyond techno-economic assumptions, and cover Avoid, Shift, and Improve strategies, as well as their combination. The results show that sufficiency - Avoid and Shift strategies - have the same impact as the improvement of propulsion technologies (i.e. efficiency), which is reduction of generation capacities by one quarter. This lowers energy system transformation cost accordingly, but requires different kinds of investments: Sufficiency measures require public investment for high-quality public services, while efficiency measures require individuals to purchase more expensive vehicles at their own cost. These results raise socio-political questions of system design and well-being. However, all strategies are required to unleash the full potential of climate change mitigation.

Description: In light of Egypt's transition to a green economy, this report focuses on reducing greenhouse gas (GHG) emissions and increasing resource efficiency along three different value chains in which small and medium-sized enterprises (SMEs) play a crucial role. In order to support SMEs in Egypt to take advantage of implementing greening options along value chains, more detailed analyses are needed. Therefore, the aim of this study is to analyse three selected supply chains to identify greening opportunities for SMEs. Against this background, the project report is structured as follows: Chapter 2 introduces the background with an overview over the concept of green economy followed by Egypt's economy and its green economy. This is followed by a presentation of the value chains and an overview of the respective sectors. Chapter 3 describes the research approach, methods and data collection. The following chapters examine the three selected value chains cotton, sugar beet and refrigerators, including environmental hot spots, greening options as well as the experts' evaluation of those greening options. The report concludes with key recommendations in Chapter 7.

Description: In order to limit global warming and fulfill their contributions to the Paris agreement, both Germany and Japan have set targets for climate neutrality towards the middle of the century. Reaching these goals will imply transformation of all sectors of society to avoid all fossil greenhouse gas emissions, heavy industry not the least. The focus of this study is the transformation of the petrochemical industry. This sector can become climate neutral but cannot be "decarbonized", as carbon is integral to the chemical structures of the products like polymers and solvents. Reaching climate neutrality thus means that the whole lifecycle of the petrochemical products has to be regarded. Another specific challenge is today's synergetic relation of this industry to fossil transport fuel production, which cannot be maintained in a climate neutral world. The two countries interestingly share a similar industrial structure overall, and the chemical and petrochemical industry is one of the major industries in both countries. The countries' respective chemical industries are the third and fourth largest in the world in terms of sales, but at the same time, these industries represent just over 5% of the respective countries' greenhouse gas emissions. However, these scope 1 emissions of the chemical industry itself are far less relevant than the end-of-life emissions of their products, which belong to scope 3 and are thus not counted under the chemical industry in the country greenhouse gas balances. To mediate these emissions, there is a need to set the direction, draw out paths and investigate possible alternatives for how the petrochemical industry can be become climate neutral. In this report, the existing scenario analyses, energy strategies and roadmaps dealing with this issue in the two countries are compared, as well as the current state of their petrochemical industries. We highlight similarities, differences and identify possible areas of cooperation and exchange in order to find robust paths forward for the transformation of the petrochemical industries.

Description: Vor dem Hintergrund einer kontinuierlich zunehmenden Pro-Kopf-Wohnfläche und den damit verbundenen negativen Auswirkungen auf Klima und Umwelt sollen mit dieser Arbeit die Bundesförderprogramme auf deren Anreizwirkung bezüglich eines achtsamen Umgangs mit der Ressource Wohnfläche überprüft werden. Der Fokus dieser Arbeit liegt auf den durch die Förderbank KfW durchgeführten Bundesförderprogrammen, die ein wichtiges Instrument der Nachhaltigkeitsstrategie des Bundes im Bereich Wohngebäude bilden. Mithilfe eines Screenings der aktuellen Förderprogramme der KfW sowie durch Gespräche mit Vertretenden der KfW soll kritisch beleuchtet werden, wie sich die derzeit verfolgten Leitbilder der Förderung im Wohngebäudebereich zu dem Leitbild einer achtsamen Wohnflächennutzung verhalten. Zudem sollen mögliche Anknüpfungspunkte für Suffizienzstrategien im Handlungsfeld Wohnfläche identifiziert und in den Kontext des aktuellen Sach- und Forschungsstands gestellt werden. Auf Grundlage der gewonnenen Erkenntnisse soll gezeigt werden, wie Suffizienzstrategien im Handlungsfeld Wohnfläche anhand innovativen Modellvorhaben erprobt werden können, um daraus Erkenntnisse für die Bundesförderung abzuleiten.

Description: The co-operation between municipalities and civil society actors and their independent impulses for urban development are discussed under the terms of co-production and city-making. This article summarises these activities as co-productive city-making (koSM). Forms of as well as advantages and disadvantages of koSM have been discussed in research and practice so far, but analyses of the longitudinal genesis of these activities and their significance for the development of a specific area are rare. This article uses the longitudinally collected, mixed-method data of a constellation analysis of the development of the Mirke neighbourhood in Wuppertal/Germany. Based on four points in time, the dynamics as well as the spatial development of the koSM can be presented - individually and in comparison to other developments. It can be seen that the koSM in the Mirke has grown at an above-average and dynamic rate and can accordingly be interpreted as a motor of neighbourhood development. Main actors and locations are identified. The study is the basis for a follow-up work analysing the reasons and structural effects of the koSM. The koSM is discussed both in its interrelations with municipal action and in its significance for integrated and sustainable urban development. The method of constellation analysis is critically discussed with regard to the relationship between effort and benefit.

Description: Real-world labs are witnessing continued growth and institutionalization in the field of transformation-oriented sustainability research, as well as in adjacent disciplines. With their experimental research agendas, these labs aim at sustainability transformations, however, there is still a need to improve the understanding of their impacts. Drawing from this Special Issue's contributions, we offer a broad overview of the impacts achieved by various real-world labs, highlight the diverse areas and forms of impact, and elucidate strategies as well as mechanisms for achieving impact. We present methodological advances, and address common challenges along with potential solutions for understanding and realizing impact.

Description: Beryllium isotopes have emerged as a quantitative tracer of continental weathering, but accurate and precise determination of the cosmogenic 10Be and stable 9Be in seawater is challenging, because seawater contains high concentrations of matrix elements but extremely low concentrations of 9Be and 10Be. In this study, we develop a new, time-efficient procedure for the simultaneous preconcentration of 9Be and 10Be from (coastal) seawater based on the iron co-precipitation method. The concentrations of 9Be, 10Be, and the resulting 10Be/9Be ratio for Changjiang Estuary water derived from the new procedure agree well with those obtained from the conventional procedure requiring separate preconcentration for 9Be and 10Be determinations. By avoiding the separate preconcentration, our newly developed procedure contributes toward more time-efficient handling of samples, less sample cross-contamination, and a more reliable 10Be/9Be ratio. Prior to this, we validated the iron co-precipitation method using artificial seawater and natural water samples from the Amazon Estuary regarding: (1) the “matrix effect” for Be analysis, (2) its extraction efficiency for pg g−1 levels Be in the presence and absence of organic matter, and (3) the data comparability with another preconcentration method. We calculated that for the determination of 9Be and 10Be in most open ocean seawater with typical 10Be concentrations of 〉 500 atoms g−1, good precisions (〈 5%) can be achieved using less than 3 liters of seawater compared to more than 20 liters routinely used previously. Even for coastal seawater with extremely low 10Be concentration (e.g., 100 atoms g−1), we estimate a maximum amount of 10 liters to be adequate.

Description: Accurate age estimates are crucial for assessing the life-histories of fish and providing management advice, but validation studies are rare for many species. We corroborated age estimates with annual cycles of oxygen isotopes (δ18O) in otoliths of 86 northern pike (Esox lucius) from the southern Baltic Sea, compared results with visual age estimates from scales and otoliths, and assessed bias introduced by different age-estimation structures on von Bertalanffy growth models and age-structured population models. Age estimates from otoliths were accurate, while age estimates from scales significantly underestimated the age of pike older than 6 years compared to the corroborated reference age. Asymptotic length () was larger, and the growth coefficient was lower for scale ages than for corroborated age and otolith age estimates. Consequentially, scale-informed population models overestimated maximum sustainable yield (), biomass at (), relative frequency of trophy fish (), and optimal minimum length limit but underestimated fishing mortality at (). Using scale-based ages to inform management regulations for pike may therefore result in conservative management and lost yield. The overestimated asymptotic length may instill unrealistic expectations of trophy potential in recreational anglers targeting large pike, while the overestimation in MSY would cause unrealistic expectations of yield potential in commercial fishers.

Description: The evolution of the local stress field of faults under tectonic stresses is crucial to predict earthquakes. In this study, we investigated the stress sensitivity of an analogue fault model with dimensions of 2 m × 1 m × 1 m, prepared from cement, gypsum, river sand, putty powder, and borax mixture. The angle between the fault strike and the maximum stress direction was varied, and the variation in the stress near the analogue fault (area 1200 × 400 mm; width 5 mm) was determined. The crack growth law of the analogue fault was found to be consistent with a simple Riedel shear model. A main strike-displacement zone was formed, and its direction was parallel to that of the analogue fault. Fault development was described by three stages based on stress–strain relationships: a nucleus stage, a stable growth, and an unstable growth stage. The deflection angle (the deflection angle of the local principal stresses) range of the local stress field was (− 45°, 45°), and it varied most significantly in the nucleus stage. The closer to the fault, the greater the variation range in the deflection angle. The variation range was greater in the fault compression quadrants than in the dilatation quadrants. The correlation between the deflection angle and the relative deformation velocity of the fault was stronger in the stable growth stage than in the other stages. In this stage, the angle–deformation–velocity correlation could be well fitted using a logistic trend model. These findings can be of importance to better understand the nucleation and mechanisms of fault slip-induced earthquakes under varying fault-strike-stress conditions.

Description: The yield and composition of tar depending on coal rank and pressure during underground coal gasification (UCG) were studied. Two coals were used in a series of ex-situ UCG experiments: a Welsh semi-anthracite (Six Feet) and a Polish bituminous coal (Wesoła). Four high-pressure gasification trials under two distinct pressure regimes (20 and 40 bar) were conducted. The tar samples were collected directly from the reactor outlet. The following groups of compounds were analysed by use of gas chromatography (GC-MS): light monoaromatic hydrocarbons (BTEX – benzene, toluene, ethylbenzene and xylenes), polycyclic aromatic hydrocarbons (PAHs) and phenols. A series of gasification experiments revealed significant differences in tar yields and composition depending on the coal rank and gasification pressure. Significant decreases in tar contents were observed with the increase in gasification pressure from 20 to 40 bar for both coals. The total yields of the analysed tar components per kg of gasified coal were 2.58 g and 0.41 g for the experiments conducted on the Six Feet samples at 20 bar and 40 bar, respectively. The corresponding values for the Wesoła coal amounted to 5.48 g and 0.95 g. In all experiments, BTEX was a dominant group of tar components, constituting 69–86 % of the total tar yield within the tested range of compounds. The present study further proves that gasification pressure has a significant effect on the chemical composition of the produced UCG tars for both coal samples under study.

Description: In this article, a high-resolution acoustic emission sensor, accelerometer, and broadband seismometer array data set is made available and described in detail from in situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility of generating multi-stage heat exchangers in a controlled way superiorly to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in situ stress and is monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the nearby tunnel system. Three different fluid injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30m30m30m at depth. We collected geological data from core and borehole logs, fracture inspection data from an impression packer, and acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication are important steps in both upscaling laboratory tests and downscaling field tests in granitic rock in the framework of enhanced geothermal system research. Data described in this paper can be accessed at GFZ Data Services under https://doi.org/10.5880/GFZ.2.6.2023.004 (Zang et al., 2023).

Description: In space geodetic techniques, the mapping functions (MFs) provide the relationship between zenith and slant tropospheric delays. The MFs are determined under the assumption of spherically layered atmosphere. However, the atmosphere is not spherically layered, and the asymmetry should be considered. Therefore, tropospheric gradients are taken into account. Nevertheless, tropospheric gradients alone can not fully represent the deviation from a spherically layered atmosphere, and hence cm level errors arise especially for low elevation angles. In this study, we present new approaches to modify the wet MF to reduce mismodelling of tropospheric delays. The delays in the study were calculated using ray-tracing algorithm based on ECMWF’s ERA5 dataset. We first analyzed the performances of the new approaches. Then, two Precise Point Positioning (PPP) simulation studies and a real case study were carried out for two different regions namely Germany and Türkiye. According to the results, the proposed approaches reduce the modelling errors up to by a factor 6 for both regions. Besides, simulation studies show that the approaches improve the accuracies of the ZTDs and heights. In the practical application however, we could not find a clear improvement in the PPP analyze and this might be related to the ERA5 which can not be regarded error-free.

Description: Geothermal energy is one of the most viable sources of renewable heat. However, the potential risk of induced seismicity associated with geothermal operations may slow down the growth of the geothermal sector. Previous research has led to significant progress in understanding fluidinjection- induced seismicity in geothermal reservoirs. However, an in-depth assessment of thermal effects on the seismic risk was generally considered to be of secondary importance. This study aims to investigate the relative influence of temperature and key geological and operational parameters on the slip tendency of pre-existing faults. This is done through coupled thermo-hydro-mechanical simulations of the injection and production processes in synthetic geothermal reservoir models of the most utilized and potentially exploitable Dutch geothermal reservoir formations: Slochteren sandstone, Delft sandstone and Dinantian limestone. In our study, changes in the slip tendency of a fault can largely be attributed to thermo-elastic effects, which confirms the findings of recent studies linking thermal stresses to induced seismicity. While the direct pore pressure effect on slip tendency tends to dominate over the early phase of the operations, once pore pressure equilibrium is established in a doublet system, it is the additional stress change associated with the growing cold-water front around the injection well that has the greatest influence. Therefore, the most significant increase in the slip tendency was observed when this low-temperature front reached the fault zone. The distance between an injection well and a pre-existing fault thus plays a pivotal role in determining the mechanical stability of a fault. A careful selection of a suitable target formation together with an appropriate planning of the operational parameters is also crucial to mitigate the risk of induced seismicity. Besides the well-known relevance of the in situ stress field and local fault geometry, rock-mechanical properties and operation conditions exert a major influence on induced stress changes and therefore on the fault (re)activation potential during geothermal operations.

Description: The CNSC, the Canadian regulator for the nuclear industry, participated in DECOVALEX-2023 Task G that focuses on the thermo (T) - hydro (H)- mechanical (M) behaviour of rock joints. Joints are omnipresent in rock masses and are planes of weakness in the host rock. When deep geological repositories (DGRs) for radioactive waste are being considered in areas where rock joints are present, the joints could be preferential pathways for radionuclide migration. Therefore, their THM behaviour must be better understood to assess the safety of the DGR. Under different possible internal and external perturbations, a joint can move by shear and dilation. If the joint crosses the emplacement area of a waste container, the heat generated from the waste can itself induce shearing of the joint. Excessive shear movement can in turn lead to failure of the container, resulting in earlier release of radionuclides. Furthermore, dilation that might accompany shear, results in an increase in the joint aperture creating a faster flow path for radionuclide transport. Mathematical models are important tools that need to be developed and employed, in order to assess joint shear and dilation under different loading conditions, such as the heat generated from the emplaced waste. The authors have developed such a mathematical model based on a macroscopic formulation within the framework of elasto-plasticity. It is verified against analytical solutions and validated against shear under constant normal load tests and thermal shearing tests of joints in granite.

Description: Biophotonic nanostructures rarely withstand fossilization processes occurring after burial over geologic time. Even more distinctive is a change introduced to the optical properties during diagenetic processes resulting in a different optical appearance. Here, we report and explain the optical appearance of centric diatom frustules obtained from ash-bearing carbonate-cemented concretions on the Greifswalder Oie island (Pomeranian Bay, Germany, southern Baltic Sea). The ultrastructural and mineralogical analysis of the fossil frustules were carried out using electron microscopy techniques and were correlated to the macroscopic and microscopic optical appearance of the frustules before and after acid etching. The unique optical properties of the fossil diatoms were associated with diagenetic nanocrystalline calcite filling the frustules’ areolae. This fill created the macroscopic pale-yellow colour of many frustules, a microscopic iridescence probably associated with diffraction grating behaviour, and microscopic colour rings. The results highlight the unique permineralization process of diatom frustules and might be an addition to the emerging studies on frustule optics and photonics.

Description: Most of in-situ stress data in the Australian continent comes from wellbore stress analysis in deep hydrocarbon reservoirs, and earthquake focal mechanism solutions near the Australian plate boundaries, where geophysical tools facilitate understanding of the present-day stress patterns. This resulted in a paucity of stress information in many other regions such as the northern Bowen Basin, which is an active mining province, but with low seismicity rates and limited deep petroleum exploration. The mining industry runs several hundred kilometres of image logs annually to characterise geotechnical attributes. These logs provide an image from the borehole wall, which facilitates analysis of stress-related borehole deformations for in-situ stress characterisation. This paper examines the orientation of horizontal in-situ stress using different types of image logs in mine boreholes across the northern Bowen Basin. Analyses of 128 km of image logs in 680 vertical boreholes resulted in the interpretation of 9046 pairs of stress-related indicators including 735 drilling induced fractures and 8311 borehole breakouts. Our comprehensive database comprises 890 quality-ranked data records for the orientation of maximum horizontal stress (SHmax), which makes the Bowen Basin as a basin with the highest data density in the world in terms of quality-ranked stress information according to the World Stress Map. Statistical analysis of SHmax orientation reveals that the mean SHmax orientation in northern Bowen Basin is N018◦ ± 16◦. The results show that this orientation is consistent over long distances, which is in contrast with several eastern Australian basins. This uniform stress pattern agrees well with plate-scale geomechanical model predictions, which further highlights the impact of plate boundary forces in the contemporary stress pattern of this region. Detailed image log investigation did not show any systematic rotation of stress; however, some small-scale stress perturbations were observed in the vicinity of sharp stiffness contrasts and geological structures.

Description: The microbiota is attributed to be important for initial soil formation under extreme climate conditions, but experimental evidence for its relevance is scarce. To fill this gap, we investigated the impact of in situ microbial communities and their interrelationship with biocrust and plants compared to abiotic controls on soil formation in initial arid and semiarid soils. Additionally, we assessed the response of bacterial communities to climate change. Topsoil and subsoil samples from arid and semiarid sites in the Chilean Coastal Cordillera were incubated for 16 weeks under diurnal temperature and moisture variations to simulate humid climate conditions as part of a climate change scenario. Our findings indicate that microorganism-plant interaction intensified aggregate formation and stabilized soil structure, facilitating initial soil formation. Interestingly, microorganisms alone or in conjunction with biocrust showed no discernible patterns compared to abiotic controls, potentially due to watermasking effects. Arid soils displayed reduced bacterial diversity and developed a new community structure dominated by Proteobacteria, Actinobacteriota, and Planctomycetota, while semiarid soils maintained a consistently dominant community of Acidobacteriota and Proteobacteria. This highlighted a sensitive and specialized bacterial community in arid soils, while semiarid soils exhibited a more complex and stable community. We conclude that microorganism-plant interaction has measurable impacts on initial soil formation in arid and semiarid regions on short time scales under climate change. Additionally, we propose that soil and climate legacies are decisive for the present soil microbial community structure and interactions, future soil development, and microbial responses.

Description: Analyzing seismic data in a timely manner is essential for potential eruption forecasting and early warning in volcanology. Here, we demonstrate that unsupervised machine learning methods can automatically uncover hidden details from the continuous seismic signals recorded during Iceland’s 2021 Geldingadalir eruption. By pinpointing the eruption’s primary phases, including periods of unrest, ongoing lava extrusion, and varying lava fountaining intensities, we can effectively chart its temporal progress. We detect a volcanic tremor sequence three days before the eruption, which may signify impending eruptive activities. Moreover, the discerned seismicity patterns and their temporal changes offer insights into the shift from vigorous outflows to lava fountaining. Based on the extracted patterns of seismicity and their temporal variations we propose an explanation for this transition. We hypothesize that the emergence of episodic tremors in the seismic data in early May could be related to an increase in the discharge rate in late April.

Description: In modelling atmospheric loading effects for terrestrial gravimetry, state-of-the-art approaches take advantage of numerical weather models to account for the global 3-D distribution of air masses. Deformation effects are often computed assuming the Inverse Barometer (IB) hypothesis to be generally valid over the oceans. By a revision of the IB assumption and its consequences we show that although the seafloor is not deformed by atmospheric pressure changes, there exists a fraction of ocean mass that current modelling schemes are usually not accounting for. This causes an overestimation of the atmospheric attraction effect over oceans, even when the dynamic response of the ocean to atmospheric pressure and wind is accounted through dynamic ocean models. This signal can reach a root mean square variability of a few nm s−2, depending on the location of the station. We therefore test atmospheric and non-tidal ocean loading effects at five superconducting gravimeter (SG) stations, showing that a better representation of the residual gravity variations is found when Newtonian attraction effects due to the IB response of the ocean are correctly considered. A sliding window variance analysis shows that the main reduction takes place for periods between 5 and 10 d, even for stations far away from the oceans. Since periods of non-tidal ocean mass variability closely resemble atmospheric signals recorded by SGs, we recommend to directly incorporate both an ocean component together with the IB into services that provide weather-related corrections for terrestrial gravimetry.

Description: More than 20 yr of measurement data of the gravity missions GRACE (Gravity Recovery And Climate Experiment) and GRACE-FO (GRACE-Follow-On) allow detailed investigations of long-term trends in continental terrestrial water storage (TWS). However, the spatial resolution of conventional GRACE/GRACE-FO data products is limited to a few hundred kilometres which restrains from investigating hydrological trends at smaller spatial scales. In this study GRACE and GRACE-FO data have been used to calculate TWS trends with maximized spatial resolution. Conventionally, GRACE/GRACE-FO is presented as a series of either unconstrained gravity fields post-processed with spatial low pass filters or constrained inversions commonly known as Mascon products. This paper demonstrates that both approaches to suppress spatially correlated noise are mathematically equivalent. Moreover, we demonstrate that readily inverting all available sensor data from GRACE/GRACE-FO for a single TWS trend map, together with annual variations and a mean gravity field, provides additional spatial detail not accessible from the standard products. The variable trade-off between spatial and temporal resolution as a unique feature of satellite gravimetry allows for gravity products that are tailored towards specific geophysical applications. We show additional signal content in terms of long-term water storage trends for four dedicated examples (Lake Victoria, Northwest India, Bugachany Reservoir and High Plains Aquifer) for which external information from other remote sensing instruments corroborates the enhanced spatial resolution of the new mean-field trend product.

Description: Ferropericlase (Mg,Fe)O is after bridgmanite the most abundant phase in the lower mantle. The ultralow velocity zones above the core-mantle boundary may contain very Fe-rich magnesiowüstite (Fe,Mg)O, possibly as result of the fractional crystallisation of a basal magma ocean. We have experimentally studied the solubility of nitrogen in the ferropericlase-magnesiowüstite solid solution series as function of iron content. Multi-anvil experiments were performed at 20–33 GPa and 1600–1800 °C in equilibrium with Fe metal. Nitrogen solubility increases from a few tens ppm (μg/g) for Mg-rich ferropericlase to more than 10 wt. % for nearly pure wüstite. Such high solubilities appear to be due to solid solution with NiAs-type FeN. Our data suggest that during fractional crystallisation of a magma ocean, the core-mantle boundary would have become extremely enriched with nitrogen, such that the deep mantle today could be the largest nitrogen reservoir on Earth. The often discussed “subchondritic N/C” ratio of the bulk silicate Earth may be an artefact of insufficient sampling of this deep reservoir.

Description: Detecting phase arrivals and pinpointing the arrival times of seismic phases in seismograms is crucial for many seismological analysis workflows. For land station data, machine learning methods have already found widespread adoption. However, deep learning approaches are not yet commonly applied to ocean bottom data due to a lack of appropriate training data and models. Here, we compiled an extensive and labeled ocean bottom seismometer (OBS) data set from 15 deployments in different tectonic settings, comprising ∼90,000 P and ∼63,000 S manual picks from 13,190 events and 355 stations. We propose PickBlue, an adaptation of the two popular deep learning networks EQTransformer and PhaseNet. PickBlue joint processes three seismometer recordings in conjunction with a hydrophone component and is trained with the waveforms in the new database. The performance is enhanced by employing transfer learning, where initial weights are derived from models trained with land earthquake data. PickBlue significantly outperforms neural networks trained with land stations and models trained without hydrophone data. The model achieves a mean absolute deviation of 0.05 s for P-waves and 0.12 s for S-waves, and we apply the picker on the Hikurangi Ocean Bottom Tremor and Slow Slip OBS deployment offshore New Zealand. We integrate our data set and trained models into SeisBench to enable an easy and direct application in future deployments.

Description: Accurate assessment of the rate and state friction parameters of rocks is essential for producing realistic earthquake rupture scenarios and, in turn, for seismic hazard analysis. Those parameters can be directly measured on samples, or indirectly based on inversion of coseismic or postseismic slip evolution. However, both direct and indirect approaches require assumptions that might bias the results. Aiming to reduce the potential sources of bias, we take advantage of a downscaled analog model reproducing megathrust earthquakes. We couple the simulated annealing algorithm with quasi-dynamic numerical models to retrieve rate and state parameters reproducing the recurrence time, rupture duration and slip of the analog model, in the ensemble. Then, we focus on how the asperity size and the neighboring segments' properties control the seismic cycle characteristics and the corresponding variability of rate and state parameters. We identify a tradeoff between (a–b) of the asperity and (a–b) of neighboring creeping segments, with multiple parameter combinations that allow mimicking the analog model behavior. Tuning of rate and state parameters is required to fit laboratory experiments with different asperity lengths. Poorly constrained frictional properties of neighboring segments are responsible for uncertainties of (a–b) of the asperity in the order of per mille. Roughly one order of magnitude larger uncertainties derive from asperity size. Those results provide a glimpse of the variability that rate and state friction estimates might have when used as a constraint to model fault slip behavior in nature.

Description: The European Geosciences Union (EGU) brings together geoscientists from all over Europe and the rest of the world, covering all disciplines of Earth, planetary and space sciences. The Division on Energy, Resources and the Environment (ERE), as part of the EGU, follows an interdisciplinary approach to serve society and provide solutions to challenges of our time and in the future. One task for humankind, for example, is to provide adequate and reliable supplies of affordable energy and other resources, obtained in environmentally sustainable ways, which will be essential for economic prosperity, environmental quality and political stability around the world. This volume of Advances in Geosciences spans the range of topics of the division and continues a series of ten ERE special issues over the course of the last ten years. We incorporate emerging topics into the division ERE along the line and we advocate that every idea and opportunity should be studied and tested.

Description: The European Geosciences Union (EGU) brings together geoscientists from all over Europe and the rest of the world, covering all disciplines of Earth, planetary and space sciences. The Division on Energy, Resources and the Environment (ERE), as part of the EGU, follows an interdisciplinary approach to serve society and provide solutions to challenges of our time and in the future. One task for humankind, for example, is to provide adequate and reliable supplies of affordable energy and other resources, obtained in environmentally sustainable ways, which will be essential for economic prosperity, environmental quality and political stability around the world. This volume of Advances in Geosciences spans the range of topics of the division and continues a series of ten ERE special issues over the course of the last ten years. We incorporate emerging topics into the division ERE along the line and we advocate that every idea and opportunity should be studied and tested.

Description: Several studies investigated changes in microbial community composition in thawing permafrost landscapes, but microbial assemblages in the transient ecosystems of the Arctic coastline remain poorly understood. Thermokarst lakes, abrupt permafrost thaw features, are widespread along the pan-Arctic coast and transform into thermokarst lagoons upon coastal erosion and sea-level rise. This study looks at the effect of marine water inundation (imposing a sulfate-rich, saline environment on top of former thermokarst lake sediments) on microbial community composition and the processes potentially driving microbial community assembly. In the uppermost lagoon sediment influenced from marine water inflow, the microbial structures were significantly different from those deeper in the lagoon sediment and from those of the lakes. In addition, they became more similar along depth compared with lake communities. At the same time, the diversity of core microbial consortia community decreased compared with the lake sediments. This work provides initial observational evidence that Arctic thermokarst lake to lagoon transitions do not only substantially alter microbial communities but also that this transition has a larger effect than permafrost thaw and lake formation history.

Description: This data set contains the results from a 2023 GFZ Innovative Research Expedition project to explore for natural hydrogen gas (H2) occurrences in the NW Pyrenean foreland, near the town of Biarritz in France. The data represent in-situ measurements of soil and spring water gas, as well as in-situ spring water property measurements, complemented with laboratory analysis results of gas contents and noble gas isotopic compositions of gas and spring water samples collected during the expedition. This GFZ Innovative Research Expedition was inspired by previous exploration efforts in the region by Lefeuvre et al. (2021, 2022). These authors detected elevated concentrations of natural H2 gas in the soil and interpreted this natural H2 to be derived from serpentinizing mantle rocks below the Pyrenees. The main aims of this expedition were the following: (1) in-situ measuring soil gas contents and taking soil gas samples for laboratory analysis at a site near the town of Peyrehorade in the NW of the general study area of Lefeuvre et al. (2021), thus improving the soil gas data coverage along the NW end of the North Pyrenean Frontal Thrust (NPFT); (2) taking gas samples from degassing springs (or water samples from non-degassing springs to be degassed in the lab) in the general Lefeuvre et al. (2021) study area for additional laboratory analysis of gas contents and noble gas isotopic compositions, which may be indicative of (deep) gas origins; and (3) performing a detailed soil gas analysis by means of a portable mass spectrometer at Sauveterre-de-Béarn, a site along the NPFT where Lefeuvre et al. (2022) measured elevated concentrations of natural H2 in the soil. Furthermore, we also measured the properties of the visited springs (temperature, pH, conductivity) while on site, and performed additional in-situ soil gas measurements from manual drillholes. Details on the measurement and sampling methods, on the laboratory analyses, as well as the results of these measurements and analyses are provided in the data description file The expedition involved six field days in July 2023, during which a total of 26 sites were visited. These sites were selected for their vicinity near a major geological contact or fault zone that could have facilitated upward circulation of gas or (thermal) water from the (deep) subsurface (i.e., potentially from the mantle).

Description: The Samail Ophiolite in the Oman Mountains formed at a Cretaceous subduction zone that was part of a wider Neo-Tethys plate-boundary system. The original configuration and evolution of this plate-boundary system is hidden in a structurally and metamorphically complex nappe stack below the Samail Ophiolite. Previous work provided evidence for high-temperature metamorphism high in the nappe pile (in the metamorphic sole of the Samail Ophiolite), and high-pressure metamorphism in the deepest part of the nappe pile (Saih Hatat window), possibly reflecting a downward younging, progressive accretion history at the Samail subduction zone. However, there is evidence that the two subduction-related metamorphic events are disparate, but temporally overlapping during the mid-Cretaceous. We present the first geochronologic dataset across the entire high-pressure nappe stack below the Samail Ophiolite, and the shear zones between the high-pressure nappes. Our 22 new Rbsingle bondSr multimineral isochron ages from the Saih Hatat window, along with independent new field mapping and kinematic reconstructions, constrain the timing and geometry of tectonometamorphic events. Our work indicates the existence of a high-pressure metamorphic event in the nappes below the ophiolite that was synchronous with the high-temperature conditions in the metamorphic sole. We argue that the thermal conditions of these synchronous metamorphic events can only be explained through the existence of two Cretaceous subduction zones/segments that underwent distinctly different thermal histories during subduction infancy. We infer that these two subduction zones initially formed at two perpendicular subduction segments at the Arabian margin and subsequently rotated relative to each other and, as a consequence, their records became juxtaposed: (1) The high-temperature metamorphic sole and the Samail Ophiolite both formed above the structurally higher, outboard, ‘hot’ and rotating Samail subduction zone and, (2) the high-pressure nappes developed within the structurally lower, inboard, ‘cold’ Ruwi subduction zone. We conclude that the formation and evolution of both subduction zones were likely controlled by the density structure of the mafic-rock-rich Arabian rifted margin and outermost Arabian Platform, and the subsequent arrival of the buoyant, largely mafic-rock-free, full-thickness Arabian lithosphere, which eventually halted subduction at the southern margin of Neo-Tethys. Previous article in issue

Description: Correction to: Rock Mechanics and Rock Engineering https://doi.org/10.1007/s00603-023-03714-4 In the original publication, the “Funding Information” and “Acknowledgements” were mistakenly swapped.

Description: Hydraulic fracturing has been widely used to enhance reservoir permeability during the extraction of shale gas. As one of the external input parameters, injection rate has a significant impact on formation breakdown pressure and the complexity of hydraulic fractures. To gain deeper insights into the effect of injection rate on breakdown pressure and fracture morphology, we conducted five hydraulic fracturing experiments on Changning shale in the laboratory. We used five different injection rates between 3 and 30 mL/min to fracture cylindrical core samples with 50 mm in diameter and 100 mm in length. We monitored acoustic emissions and surface displacements during the tests, and analyzed the fracture pattern post mortem by using a fluorescent tracer. We find a semi-logarithmic relationship between the breakdown pressure and the injection rates. Second, we find that it is the injection rate that dictates sample deformation and crack formation during breakdown rather than the fluid volume injected during the whole process. The analysis of amplitudes and frequency of acoustic signals indicates that hydraulic fracturing of Changning shale is overall dominated by tensile fractures (〉 60%). However, at low injection rates, shear events are facilitated before rock breakdown. On the other hand, high injection rates result in reducing fracture tortuosity and surface roughness due to limited fluid infiltration in the relatively short injection window. We close this study with a conceptual model to explain the difference between fluid infiltration (low injection rates) and the loading rate effect (high injection rate) in low-permeability shale rocks. The findings obtained in this study can help to adjust injection rates in the field to economically and safely produce gas from shale.

Description: Secondary ion mass spectrometry was used to test the d18O and d34S nanogram-scale homogeneity of a suite of candidate sulfate minerals, ultimately selecting three barite, two anhydrite, and two gypsum samples from the Royal Ontario Museum that have repeatabilities for their SIMS measurements of better than 0.39‰ and 0.37‰ (1s) for oxygen and sulfur isotope ratios, respectively. Metrological splits of each of the seven materials were sent to multiple gas source isotope ratio mass spectrometry laboratories in order to establish their absolute 18O/16O and 34S/32S ratios. The inter-laboratory results of GS-IRMS analyses yielded reasonably narrow ranges in d18OVSMOW, whereas larger variations in d34SVCDT values were found between the results from the gas source laboratories. All samples have good reproducibility within laboratories of GS-IRMS 103d18O values of between 0.24‰ and 0.44‰ (1s). The reproducibility within laboratories of GS-IRMS 103d34S values range from 0.07‰ to 0.99‰ (1s). Here we also discuss some of the current analytical limitations affecting these isotope-mineral systems. A total of 256 metrological splits have been prepared from each of these seven materials; these aliquots will be made available to the global geochemical community.

Description: The increasing demand for fertilizers and their rising prices has led to the search for new nutrient sources, especially in rural areas where family farming predominates. In this study, we assessed the potential of reusing sediment deposited in surface reservoirs as a soil conditioner in a semiarid region, focusing on two features: the characterization of sediment physicochemical properties at the regional scale and the effect of the substrate containing sediment on the growth and physiology of maize.

Description: The analysis of Coulomb stress changes has become an important tool for seismic hazard evaluation because such stress changes may trigger or delay subsequent earthquakes. Processes that can cause significant Coulomb stress changes include coseismic slip and transient postseismic processes such as poroelastic effects and viscoelastic relaxation. However, the combined influence of poroelastic effects and viscoelastic relaxation on co- and postseismic Coulomb stress changes has not been systematically studied so far. Here, we use three-dimensional finite-element models with arrays of normal and thrust faults to investigate how pore fluid pressure changes and viscoelastic relaxation overlap during the postseismic phase. In different experiments, we vary the permeability of the upper crust and the viscosity of the lower crust or lithospheric mantle while keeping the other parameters constant. In addition, we perform experiments in which we combine a high (low) permeability of the upper crust with a low (high) viscosity of the lower crust. Our results show that the coseismic (i.e., static) Coulomb stress changes are altered by the signal from poroelastic effects and viscoelastic relaxation during the first month after the earthquake. For sufficiently low viscosities, the Coulomb stress change patterns show a combined signal from poroelastic and viscoelastic effects already during the first postseismic year. For sufficiently low permeabilities, Coulomb stress changes induced by poroelastic effects overlap with the signals from viscoelastic relaxation and interseismic stress accumulation for decades. Our results imply that poroelastic and viscoelastic effects have a strong impact on postseismic Coulomb stress changes and should therefore be considered together when analyzing Coulomb stress transfer between faults.

Description: The impact of faults on the contemporary stress field in the upper crust has been discussed in various studies. Data and models clearly show that there is an effect, but so far, a systematic study quantifying the impact as a function of distance from the fault is lacking. In the absence of data, here we use a series of generic 3-D models to investigate which component of the stress tensor is affected at which distance from the fault. Our study concentrates on the far field, lo- cated hundreds of metres from the fault zone. The models assess various techniques to represent faults, different mate- rial properties, different boundary conditions, variable orien- tation, and the fault’s size. The study findings indicate that most of the factors tested do not have an influence on ei- ther the stress tensor orientation or principal stress magni- tudes in the far field beyond 1000 m from the fault. Only in the case of oblique faults with a low static friction coeffi- cient of μ = 0.1 can noteworthy stress perturbations be seen up to 2000 m from the fault. However, the changes that we detected are generally small and of the order of lateral stress variability due to rock property variability. Furthermore, only in the first hundreds of metres to the fault are variations large enough to be theoretically detected by borehole-based stress data when considering their inherent uncertainties. This find- ing agrees with robust stress magnitude measurements and stress orientation data. Thus, in areas where high-quality and high-resolution data show gradual and continuous stress ten- sor rotations of 〉 20◦ observed over lateral spatial scales of 10 km or more, we infer that these rotations cannot be at- tributed to faults. We hypothesize that most stress orienta- tion changes attributed to faults may originate from different sources such as density and strength contrasts.

Description: Public earthquake early warning systems (PEEWSs) have the potential to save lives by warning people of incoming seismic waves up to tens of seconds in advance. Given the scale and geographical extent of their impact, this potential is greatest for destructive earthquakes, such as the M7.8 Pazarcik (Türkiye) event of 6 February 2023, which killed almost 60,000 people. However, warning people of imminent strong shaking is particularly difficult for large-magnitude earthquakes because the warning must be given before the earthquake has reached its final size. Here, we show that the Earthquake Network (EQN), the first operational smartphone-based PEEWS and apparently the only one operating during this earthquake, issued a cross-border alert within 12 s of the beginning of the rupture. A comparison with accelerometer and macroseismic data reveals that, owing to the EQN alerting strategy, Turkish and Syrian EQN users exposed to intensity IX and above benefitted from a warning time of up to 58 s before the onset of strong ground shaking. If the alert had been extended to the entire population, approximately 2.7 million Turkish and Syrian people exposed to a lifethreatening earthquake would have received a warning ranging from 30 to 66 s in advance.

Description: The joint European Space Agency and Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will explore global dynamics of the magnetosphere under varying solar wind and interplanetary magnetic field conditions, and simultaneously monitor the auroral response of the Northern Hemisphere ionosphere. Combining these large-scale responses with medium and fine-scale measurements at a variety of cadences by additional ground-based and space-based instruments will enable a much greater scientific impact beyond the original goals of the SMILE mission. Here, we describe current community efforts to prepare for SMILE, and the benefits and context various experiments that have explicitly expressed support for SMILE can offer. A dedicated group of international scientists representing many different experiment types and geographical locations, the Ground-based and Additional Science Working Group, is facilitating these efforts. Preparations include constructing an online SMILE Data Fusion Facility, the discussion of particular or special modes for experiments such as coherent and incoherent scatter radar, and the consideration of particular observing strategies and spacecraft conjunctions. We anticipate growing interest and community engagement with the SMILE mission, and we welcome novel ideas and insights from the solar-terrestrial community.

Description: Assessing the potential and extent of earthquake-induced liquefaction is paramount for seismic hazard assessment, for the large ground deformations it causes can result in severe damage to infrastructure and pose a threat to human lives, as evidenced by many contemporary and historical case studies in various tectonic settings. In that regard, numerical modeling of case studies, using state-of-the-art soil constitutive models and numerical frameworks, has proven to be a tailored methodology for liquefaction assessment. Indeed, these simulations allow for the dynamic response of liquefiable soils in terms of effective stresses, large strains, and ground displacements to be captured in a consistent manner with experimental and in-situ observations. Additionally, the impact of soil properties spatial variability in liquefaction response can be assessed, because the system response to waves propagating are naturally incorporated within the model. Considering that, we highlight that the effect of shear-wave velocity Vs spatial variability has not been thoroughly assessed. In a case study in Metropolitan Concepción, Chile, our research addresses the influence of Vs spatial variability on the dynamic response to liquefaction. At the study site, the 2010 Maule Mw 8.8 megathrust Earthquake triggered liquefaction-induced damage in the form of ground cracking, soil ejecta, and building settlements. Using simulated 2D Vs profiles generated from real 1D profiles retrieved with ambient noise methods, along with a PressureDependentMultiYield03 sand constitutive model, we studied the effect of Vs spatial variability on pore pressure generation, vertical settlements, and shear and volumetric strains by performing effective stress site response analyses. Our findings indicate that increased Vs variability reduces the median settlements and strains for soil units that exhibit liquefaction-like responses. On the other hand, no significant changes in the dynamic response are observed in soil units that exhibit non-liquefaction behavior, implying that the triggering of liquefaction is not influenced by spatial variability in Vs. We infer that when liquefaction-like behavior is triggered, an increase of the damping at the shallowest part of the soil domain might be the explanation for the decrease in the amplitude of the strains and settlements as the degree of Vs variability increases.

Description: Trawl-fishing is broadly considered to be one of the most destructive anthropogenic activities toward benthic ecosystems. In this study, we examine the effects of bottom-contact fishing by otter trawls on the geochemistry and macrofauna in sandy silt sediment in an area of the Baltic Sea where clear spatial patterns in trawling activity were previously identified by acoustic mapping. We calibrated an early diagenetic model to biogeochemical data from various coring locations. Fitting measured mercury profiles allowed for the determination of the sediment mixing and burial velocity. For all sites, independent of the trawl mark density, good fits were obtained by applying the model with the same organic matter loading and parameter values, while iron fluxes scaled linearly with the burial velocity. A sensitivity analysis revealed that the fitted sulfate reduction rate, solid sulfur contents, ammonium concentration, and both the isotopic composition and concentration of dissolved inorganic carbon provided reliable constraints for the total mineralization rate, which exhibited a narrow range of variability (around ±20 % from the mean) across the sites. Also, the trawling intensity did not significantly correlate with total organic carbon contents in surficial sediment, indicating limited loss of organic matter due to trawling. The fits to the reactive iron, acid volatile sulfur, chromium(II) reducible sulfur contents, and porewater composition demonstrate that sediment burial and mixing primarily determine the redox stratification. The mixing depth did not correlate with trawling intensity and is more likely the result of bioturbation, as the analyzed macrofaunal taxonomy and density showed a high potential for sediment reworking. The extraordinarily long-lived Arctica islandica bivalve dominated the infaunal biomass, despite the expectation that trawling leads to the succession from longer-lived to shorter-lived and bigger to smaller macrofauna. Our results further suggest that a clear geochemical footprint of bottom-trawling may not develop in sediments actively reworked by tenacious macrofauna.

Description: Grain boundary networks of quartz, plagioclase and olivine crystal aggregates in metamorphic rocks have been investigated from the nanometer to the millimeter scale by polarized-light microscopy, SEM, and TEM. The studied materials show different grain sizes and experienced different retrograde P-T histories. The aggregates of quartz and plagioclase are traversed by networks of ∼90% continuously open boundaries with μm-sized cavities along the boundaries or at triple junctions. The boundaries are up to ∼500 nm wide open with typically parallel opposing grain faces. Olivine boundaries are filled with serpentine that does not replace olivine but fills the initially open space homogeneously and mostly with random orientation. For quartz there is no correlation between the crystallographic orientation of grain boundaries and their widths. Amongst all samples analyzed, a weak positive correlation exists between grain size and width of open grain boundaries. The application of measured volume changes and elasticity data from the literature to the cooling-decompression paths of the analyzed materials suggests that fracturing with subsequent widening of the grain boundaries starts at temperatures recognizably below the transition from crystal-plastic to brittle behavior of quartz, plagioclase and olivine but not only under surface conditions. The high amount of open boundaries causes an extensive permeability.

Description: Pit lakes in the ‘anthropogenic lake district’ in the Muskau Arch (western Poland; central Europe) are strongly affected by acid mine drainage (AMD). The studied acidic pit lake, ŁK-61 (pH 〈3), is also exposed to floods due to its location in the flood hazard area, which may significantly influence the geochemical behavior of elements. The elemental compositions of water and lake sediment samples were measured with ICP–OES and ICP–MS. The sediment profile was also examined for 137Cs and 210Po activity concentrations using gamma and alpha spectrometry, respectively. Grain size distribution, mineralogical composition, diatoms, and organic matter content in the collected core were also determined. The key factors responsible for the distribution of selected heavy metals (e.g., Cu, Ni, Pb, Zn) and radioisotopes (137Cs and 210Po) in the bottom sediments of Lake ŁK-61 are their coprecipitation/precipitation with Fe and Al secondary minerals and their sorption onto authigenic and allogenic phases. These processes are likely driven by the lake tributary, which is an important source of dissolved elements. The data also showed that the physiochemical parameters of Lake ŁK-61 water changed during an episodic depositional event, i.e., the flood of the Nysa Łużycka River in the summer of 2010. The flood caused an increase in the water pH, as interpreted from the subfossil diatom studies. The down-core profiles of the studied heavy metal and radionuclide (HMRs) contents were probably affected by this depositional event, which prevented a detailed age determination of the collected lake sediments with 137Cs and 210Pb dating methods. Geochemical modeling indicates that the flood-related shift in the physicochemical parameters of the lake water could have caused the scavenging of dissolved elements by the precipitation of fresh secondary minerals. Moreover, particles contaminated with HMRs have also possibly been delivered by the river, along with the nutrients (e.g., phosphorus and nitrogen).

Description: Contemporary quantum plasmonics capture subtle corrections to the properties of plasmonic nano-objects in equilibrium. Here, we demonstrate non-equilibrium spill-out redistribution of the electronic density at the ultrafast time scale. As revealed by time-resolved 2D spectroscopy of nanoplasmonic Fe/Au bilayers, an injection of the laser-excited non-thermal electrons induces transient electron spill-out thus changing the plasma frequency. The response of the local electronic density switches the electronic density behavior from spill-in to strong (an order of magnitude larger) spill-out at the femtosecond time scale. The superdiffusive transport of hot electrons and the lack of a direct laser heating indicate significantly non-thermal origin of the underlying physics. Our results demonstrate an ultrafast and non-thermal way to control surface plasmon dispersion through transient variations of the spatial electron distribution at the nanoscale. These findings expand quantum plasmonics into previously unexplored directions by introducing ultrashort time scales in the non-equilibrium electronic systems.

Description: The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including ‘true inoceramids’ and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, S isotopes in carbonate-associated sulfate, along with C and O isotopes in foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50–100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration in seawater. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses

Description: The structural response to compression of the synthetic high-pressure hydroxide perovskite MgSi(OH)6, the so-called “3.65 Å phase,” has been determined to 8.4 GPa at room temperature using single-crystal XRD in the diamond-anvil cell. Two very similar structures have been determined in space groups P21 and P21/n, for which differences in oxygen donor-acceptor distances indicate that the non-centrosymmetric structure is likely the correct one. This structure has six nonequivalent H sites, of which two are fully occupied and four are half-occupied. Half-occupied sites are associated with a well-defined crankshaft of hydrogen-bonded donor-acceptor oxygens extending parallel to c. Half occupancy of these sites arises from the averaging of two orientations of the crankshaft H atoms (|| ±c) in equal proportions. The P21 and P21/n structures are compared. It is shown that the former is likely the correct space group, which is also consistent with recent spectroscopic studies that recognize six nonequivalent O-H. The structure of MgSi(OH)6 at pressures up to 8.4 GPa was refined in both space groups to see how divergent the two models are. There is a very close correspondence between the responses of the two structures implying that, at least to 8.4 GPa, non-centrosymmetry does not affect compressional behavior. The very different compressional behavior of MgO6 and SiO6 octahedra observed in this study suggests that structural phase transformations or discontinuities likely occur in MgSi(OH)6 above 9 GPa.

Description: The Combination Service for Time-variable Gravity fields (COST-G) operationally provides combinations of monthly Earth gravity field models derived from observations of the microwave ranging instrument of the GRACE Follow-on (GRACE-FO) satellite mission, applying the quality control and combination methodology originally developed by the Horizon 2020 project European Gravity Service for Improved Emergency Management for the data of the GRACE satellites. In the frame of the follow-up Horizon 2020 project Global Gravity-based Groundwater Product (G3P), the GRACE-FO combination is used to derive global grids of groundwater storage anomalies. To meet the user requirements and achieve optimal signal-to-noise ratio, the combination has been further developed and extended to incorporate: • new time-series based on the alternative accelerometer transplant product generated in the frame of the project by the Institute of Geodesy at the Graz University of Technology, which specifically improves the estimation of the C30 coefficient and also reduces the noise at medium to short wavelengths, and • the new time-series AIUB–GRACE-FO–RL02 of monthly GRACE-FO gravity fields, which is derived at the Astronomical Institute of the University of Bern by applying empirical noise modelling techniques. The COST-G quality control confirms the consistency of the contributing GRACE-FO time-series concerning the signal amplitude of seasonal hydrology in large river basins and the secular mass change in polar regions, but it also indicates rather diverse noise characteristics. The difference in the noise levels is taken into account in the combination process by relative weights derived by variance component estimation on the solution level. The weights are expected to be inverse proportional to the noise levels of the individual gravity field solutions. However, this expectation is violated when applying the weighting scheme as developed for the GRACE combination. The reason is found in the high-order coefficients of the gravity field, which are poorly determined from the low–low range-rate observations due to the observation geometry and suffer from aliasing due to the malfunctioning accelerometer onboard one of the GRACE-FO satellites. Hence, for the final G3P-combination a revised weighting scheme is applied where the gravity field coefficients beyond order 60 are excluded from the determination of the weights. The quality of the combined gravity fields is assessed by comparison of the noise content and the signal-to-noise ratio with the individual time-series. Independent validation is provided by the COST-G validation centre at the GFZ German Research Centre for Geosciences, where orbit fits of the low-flying Gravity and steady-state Ocean Circulation Explorer satellite are performed that confirm the high quality of the combined GRACE-FO gravity fields. By the end of the G3P project, the new combination scheme is implemented by COST-G as the new COST-G–GRACE-FO–RL02 and continued to be used for the operational GRACE-FO combination.

Description: With the ongoing deployment of Global Navigation Satellite Systems (GNSS) ground stations and the modernization of satellite signal systems, the utilization of various augmentation technologies enables the realization of Precise Point Positioning (PPP) in real-time. Augmentation technology, which introduces precise atmospheric and signal-related delays, has become an essential component of high-precision real-time services and is attracting growing interest in scientific research, disaster monitoring, autopilot, etc. Previous studies have dedicated significant efforts to enhance the generation and dissemination of augmentation information on the service side and improve real-time positioning algorithms on the user side. The real-time atmosphere augmentation information with sufficient accuracy and proper constraint, and reliable Ambiguity Resolution (AR) for this purpose is the main focus of current GNSS research. However, these efforts have primarily been concentrated on small or medium-sized regions with the capability for transmitting massive data volumes. Alternatively, they have focused on larger areas, but with slow convergence due to the imprecise nature of atmosphere information. To address the challenge posed by the trade-offs among service area size, correction volume, and the precision of represented correction, a new augmentation strategy is proposed. This approach integrates the advantages of atmospheric delay fitting models, unmodeled residuals, and uncertainty information to achieve rapid and high-precision positioning, all while reducing data transmission volume for larger areas. It also allows users to implement different positioning modes depending on their communication capacity. Additionally, all deviations among different types of receivers and satellite signals are calibrated in this study for reliable AR can be achieved on all reference stations. The main contribution of this thesis is summarized as follows. With the real-time precise orbit, clock, and Uncalibrated Phase Delay (UPD) products, precise atmospheric delay corrections relying on reliable AR can be derived for large-areas augmentation services. To address the challenge of achieving reliable AR across different receiver types and various satellite signals, this thesis proposes a comprehensive method for calibrating receiver-type-related satellite-specific deviations and analyzes the impact of satellite signal bias corrections in data processing. The primary objective is to enhance the reliability of AR, enabling the utilization of all available signals and receiver types in large-area services. Subsequently, new tropospheric and ionospheric delay fitting models applied for large-area are carried out according to the properties of their propagation paths. In addition, the corresponding atmospheric delay uncertainty for large areas is introduced based on the fitting residuals. Finally, a hierarchical mode is developed for augmentation services, leveraging the advantages of the fitting model and uncertainty grid to reduce data volume and incorporating regional fitting residuals using the interpolation model and ionospheric delay error function, depending on the network capability. Based on hierarchical augmentation, positioning in large areas can not only achieve rapid/instantaneous high-precision convergence but also overcome the conflict among correction volume, represented precision, and coverage size. In order to derive precise atmospheric delay and accelerate positioning, implementing reliable and robust AR across all types of receivers and satellite signals is essential. It also demonstrates and discusses the advantages of calibrating satellite-signal and receiver-type-related satellite-specific deviations in AR solutions. The deviations related to receivers in terms of UPD products are assessed and calibrated, confirming that a 0.03 cycle consistency in wide lane UPD can be achieved. The effectiveness of the proposed approach is demonstrated using GPS satellite signals, which can improve the AR rate by at least 10% and produce more reliable results. In addition, the impact of different signal settings and corrections on orbit, clock, and UPD generation, as well as positioning and pseudo-range signal systematic and stochastic residuals, is analyzed. These processing strategies provide flexible observation selections, allowing the utilization of all available satellite signals and receiver types, thereby enabling reliable AR and a higher fixing rate. As a result, an AR fixing rate exceeding 95% is achievable across all stations in large-area services. For precise atmospheric delay modeling over large areas, new models are proposed, including a tropospheric Zenith Wet Delay (ZWD) model and a satellite-wise ionospheric slant delay fitting model. The tropospheric delay model takes the exponential function of water vapor vertical changes into consideration, addressing model anomalies in areas with large altitude differences. The new ionospheric delay fitting model introduces the trigonometric functions to describe differences in slant path delays between the optimal reference propagation path and others, achieving superior modeling performance in large areas. The precision of the fitting model, utilizing a 200 km station-spacing network, demonstrates tropospheric ZWD and ionospheric slant delays of 1.3 cm and 8.9 cm, respectively, with smaller standard deviations. These new fitting models overcome the challenge of handling massive information for providing station-wise corrections and avoid an increase in the number of coefficients. In addition to the function model, the stochastic model, i.e., uncertainty information, is essential for describing the quality of corrections. The atmospheric delay uncertainty for the large-area fitting model is generated based on the fitting residuals and represented in forms of grid-point. Additionally, regional ionosphere unmodeled residual uncertainty is represented by the form of liner function, which is established by the relationship between distance and interpolation precision through inter-satellite cross-verification among all reference stations. The differences between uncertainty value and real delays are 2.5 cm and 0.5 cm for grid and function forms, respectively. For real-time applications in large areas, the fitting model and grid-based atmosphere uncertainty serve as the essential information, satisfying the requirement of rapid positioning. By further incorporating unmodeled residuals and ionosphere error function, a hierarchical augmentation model is provided. Based on the fitting model established for large areas, unmodeled residuals are further introduced as optional compensation for specific areas, depending on the magnitude of fitting residuals. This approach results in a 97% reduction in tropospheric delay and a 65% reduction in ionospheric delay transmission volume. Furthermore, leveraging the regional high capability of communication, 85.3% of all solutions can achieve instantaneous convergence at the first epoch with the aid of corresponding regional compensation. This thesis proposes a large areas augmentation service to overcome the conflict among correction data volume, represented precision, and coverage size. It demonstrates the benefits of an augmentation mode that integrates regional information into large-area services. Under these conditions, a more reliable and rapid AR solution can be easily achieved based on precise atmospheric delay correction and uncertainty in large areas with fewer data volume requirements. This is beneficial for actual real-time services and applications.

Description: Mit der laufenden Bereitstellung von Bodenstationen für globale Navigationssatellitensysteme (GNSS) und der Modernisierung von Satellitensignal-Systemen ermöglicht die Nutzung verschiedener Augmentationstechnologien die Realisierung der Präzisen Punkt-Positionierung (PPP) in Echtzeit. Augmentationstechnologie, die präzise atmosphärische und signalbezogene Verzögerungen einführt, ist zu einem wesentlichen Bestandteil hochpräziser Echtzeitdienste geworden und findet wachsendes Interesse in wissenschaftlicher Forschung, Katastrophenüberwachung, Autopiloten usw. Frühere Studien haben erhebliche Anstrengungen darauf verwendet, die Erzeugung und Verbreitung von Augmentationsinformationen auf der Dienstseite zu verbessern und Echtzeit-Positionierungsalgorithmen auf der Benutzerseite zu optimieren. Die Echtzeit-Atmosphärenaugmentationsinformationen mit ausreichender Genauigkeit und angemessener Einschränkung sowie zuverlässige Ambiguitätsauflösung (AR) für diesen Zweck stehen im Mittelpunkt der aktuellen GNSS-Forschung. Diese Bemühungen konzentrierten sich jedoch hauptsächlich auf kleine oder mittelgroße Regionen mit der Fähigkeit zur Übertragung großer Datenmengen. Alternativ richteten sie sich auf größere Gebiete, jedoch mit langsamer Konvergenz aufgrund der ungenauen Natur der Atmosphäreninformation. Um der Herausforderung durch die Abwägung zwischen Größe des Dienstleistungsgebiets, Korrekturvolumen und Präzision der dargestellten Korrektur zu begegnen, wird eine neue Augmentationsstrategie vorgeschlagen. Dieser Ansatz integriert die Vorteile atmosphärischer Verzögerungsanpassungsmodelle, nicht modellierter Reste und Unsicherheitsinformationen, um eine schnelle und hochpräzise Positionierung zu erreichen, und das bei gleichzeitiger Reduzierung der Datenübertragungsvolumina für größere Gebiete. Es ermöglicht den Benutzern auch, verschiedene Positionierungsmodi je nach ihrer Kommunikationskapazität zu implementieren. Zusätzlich werden in dieser Studie alle Abweichungen zwischen verschiedenen Typen von Empfängern und Satellitensignalen kalibriert, um eine zuverlässige AR an allen Referenzstationen zu erreichen. Die Hauptbeiträge dieser Arbeit werden wie folgt zusammengefasst. Mit den Echtzeit-Präzbitbahnen, Uhren und Uncalibrated Phase Delay (UPD)-Produkten können präzise atmosphärische Verzögerungskorrekturen für großflächige Augmentationsdienste abgeleitet werden, die auf zuverlässiger AR basieren. Um die Herausforderung zu bewältigen, eine zuverlässige AR über verschiedene Empfängertypen und verschiedene Satellitensignale hinweg zu erreichen, schlägt diese Arbeit eine umfassende Methode zur Kalibrierung von empfängertypbezogenen satellspezifischen Abweichungen vor und analysiert die Auswirkungen von Korrekturen für Satellitensignalverzerrungen in der Datenverarbeitung. Das Hauptziel besteht darin, die Zuverlässigkeit der AR zu verbessern und die Nutzung aller verfügbaren Signale und Empfängertypen in großflächigen Diensten zu ermöglichen. Anschließend werden neue troposphärische und ionosphärische Verzögerungsanpassungsmodelle für großflächige Anwendungen gemäß den Eigenschaften ihrer Ausbreitungspfade durchgeführt. Darüber hinaus wird die entsprechende atmosphärische Verzögerungsunsicherheit für große Gebiete auf der Grundlage der Anpassungsreste eingeführt. Schließlich wird ein hierarchischer Modus für Augmentationsdienste entwickelt, der die Vorteile des Anpassungsmodells und des Unsicherheitsgitters nutzt, um das Datenvolumen zu reduzieren und regionale Anpassungsreste unter Verwendung des Interpolationsmodells und der ionosphärischen Verzögerungsfehlerfunktion, abhängig von der Netzwerkfähigkeit, zu integrieren. Basierend auf der hierarchischen Augmentation kann die Positionierung in großen Gebieten nicht nur eine schnelle/instantane hochpräzise Konvergenz erreichen, sondern auch den Konflikt zwischen Korrekturvolumen, dargestellter Präzision und Abdeckungsgröße überwinden. Um präzise atmosphärische Verzögerungen abzuleiten und die Positionierung zu beschleunigen, ist es entscheidend, eine zuverlässige und robuste AR über alle Arten von Empfängern und Satellitensignalen zu implementieren. Es zeigt auch die Vorteile der Kalibrierung von satellitensignal- und empfängertypbezogenen satellspezifischen Abweichungen in AR-Lösungen auf. Die Abweichungen im Zusammenhang mit Empfängern in Bezug auf UPD-Produkte werden bewertet und kalibriert, wobei bestätigt wird, dass eine Konsistenz von 0,03 Zyklen bei Wide-Lane-UPD erreicht werden kann. Die Wirksamkeit des vorgeschlagenen Ansatzes wird unter Verwendung von GPS-Satellitensignalen demonstriert, die die AR-Rate um mindestens 10% verbessern und zu zuverlässigeren Ergebnissen führen können. Darüber hinaus wird der Einfluss unterschiedlicher Signalparameter und Korrekturen auf die Erzeugung von Orbit, Uhr und UPD sowie auf die Positionierung und systematische und stochastische Reste der Pseudo-Range-Signale analysiert. Diese Verarbeitungsstrategien bieten flexible Auswahlmöglichkeiten bei der Beobachtung und ermöglichen die Nutzung aller verfügbaren Satellitensignale und Empfängertypen, wodurch eine zuverlässige AR und eine höhere Fixierungsrate ermöglicht wird. Als Ergebnis ist eine AR-Fixierungsrate von über 95% bei allen Stationen in großflächigen Diensten erreichbar. Für eine präzise Modellierung atmosphärischer Verzögerungen über großen Gebieten werden neue Modelle vorgeschlagen, darunter ein troposphärisches Zenith Wet Delay (ZWD)-Modell und ein satellitenweises ionosphärisches Schrägverzögerungsanpassungsmodell. Das troposphärische Verzögerungsmodell berücksichtigt die exponentielle Funktion der vertikalen Änderungen des Wasserdampfs und behebt Modellanomalien in Gebieten mit großen Höhendifferenzen. Das neue ionosphärische Verzögerungsanpassungsmodell verwendet trigonometrische Funktionen, um Unterschiede in den Schrägpfadverzögerungen zwischen dem optimalen Referenzausbreitungspfad und anderen zu beschreiben und erreicht so eine überlegene Modellierungsleistung in großen Gebieten. Die Präzision des Anpassungsmodells, unter Verwendung eines 200 km-Stationen-Netzwerks, zeigt troposphärische ZWD- und ionosphärische Schrägverzögerungen von jeweils 1,3 cm und 8,9 cm mit kleineren Standardabweichungen. Diese neuen Anpassungsmodelle überwinden die Herausforderung, massive Informationen für die Bereitstellung stationsspezifischer Korrekturen zu verarbeiten, und vermeiden eine Zunahme der Anzahl der Koeffizienten. Neben dem Funktionsmodell ist das stochastische Modell, d. h. Unsicherheitsinformationen, entscheidend für die Beschreibung der Qualität der Korrekturen. Die Unsicherheit der atmosphärischen Verzögerung für das großflächige Anpassungsmodell wird auf der Grundlage der Anpassungsreste generiert und in Form von Gitterpunkten dargestellt. Zusätzlich wird die regionale ionosphärische nicht modellierte Restunsicherheit durch die Form einer linearen Funktion repräsentiert, die durch die Beziehung zwischen Entfernung und Interpolationsgenauigkeit durch inter-satellitenkreuz-Verifikation zwischen allen Referenzstationen etabliert wird. Die Unterschiede zwischen Unsicherheitswert und realen Verzögerungen betragen 2,5 cm bzw. 0,5 cm für Gitter- und Funktionsformen. Für Echtzeitanwendungen in großen Gebieten dienen das Anpassungsmodell und die gitterbasierte Atmosphärenunsicherheit als wesentliche Informationen, die die Anforderungen an schnelle Positionierung erfüllen. Durch die weitere Integration von nicht modellierten Resten und Ionosphärenfehlerfunktion wird ein hierarchisches Augmentationsmodell bereitgestellt. Basierend auf dem für große Gebiete etablierten Anpassungsmodell werden nicht modellierte Reste zusätzlich als optionale Kompensation für spezifische Bereiche eingeführt, abhängig von der Größenordnung der Anpassungsreste. Dieser Ansatz führt zu einer Reduktion von 97% der troposphärischen Verzögerung und einer Reduktion von 65% des ionosphärischen Verzögerungsvolumens. Darüber hinaus können unter Nutzung der regionalen hohen Kommunikationsfähigkeit 85,3% aller Lösungen mit Hilfe entsprechender regionaler Kompensation eine sofortige Konvergenz beim ersten Epochenzeitpunkt erreichen. Diese Dissertation schlägt einen großflächigen Augmentationsdienst vor, um den Konflikt zwischen Korrekturvolumen, dargestellter Präzision und Abdeckungsgröße zu überwinden. Sie zeigt die Vorteile eines Augmentationsmodus, der regionale Informationen in großflächige Dienste integriert. Unter diesen Bedingungen kann eine zuverlässigere und schnellere AR-Lösung basierend auf präziser atmosphärischer Verzögerungskorrektur und Unsicherheit in großen Gebieten mit geringeren Anforderungen an das Datenvolumen leicht erreicht werden. Dies ist vorteilhaft für tatsächliche Echtzeitdienste und Anwendungen.

Description: Inland water bodies play a vital role at all scales in the terrestrial water balance and Earth’s climate variability. Thus, an inventory of inland waters is crucially important for hydrologic and ecological studies and management. Therefore, the main aim of this study was to develop a deep learning-based method for inventorying and mapping inland water bodies using the RGB band of high-resolution satellite imagery automatically and accurately. The Sentinel-2 Harmonized dataset, together with ZABAGED-validated ground truth, was used as the main dataset for the model training step. Three different deep learning algorithms based on U-Net architecture were employed to segment inland waters, including a simple U-Net, Residual Attention U-Net, and VGG16-U-Net. All three algorithms were trained using a combination of Sentinel-2 visible bands (Red [B04; 665nm], Green [B03; 560nm], and Blue [B02; 490 nm]) at a 10-meter spatial resolution. The Residual Attention U-Net achieved the highest computational cost due to the increased number of trainable parameters. The VGG16-U-Net had the shortest run time and the lowest number of trainable parameters, attributed to its architecture compared to the simple and Residual Attention U-Net architectures, respectively. As a result, the VGG16-U-Net provided the best segmentation results with a mean-IoU score of 0.9850, a slight improvement compared to other proposed U-Net-based architectures. Although the accuracy of the model based on VGG16-U-Net does not make a difference from Residual Attention U-Net, the computation costs for training VGG16-U-Net were dramatically lower than Residual Attention U-Net.

Description: Northeastern Eurasia is one of the least explored regions in the world. Very little geophysical data is available for this inaccessible area. Even the exact location of the plate boundary between Eurasia and North America remains a subject of ongoing debate. The effective elastic thickness (EET) of the lithosphere is a proxy for lithospheric strength and can provide insight into the thermal regime and tectonic processes. We have computed a high-resolution map of the EET for northeastern Eurasia using the fan wavelet coherence technique applied to the Bouguer gravity anomalies and topography/bathymetry data, appropriately adjusted to account for the influence of density variations within sediments. The results obtained provide insights into different tectonic regimes within this predominantly understudied region. In particular, we identify the boundary between the Eurasian and North American plates in Siberia as a rheologically weak diffusive zone extending from the Verkhoyansk and Sette-Daban Ranges to the eastern boundary of the Chersky Range. Unlike the Sette-Daban and Verkhoyansk Ranges, which were formed by plate collision and have an EET of 30–50 km, other mountainous regions have much lower EET values, usually less than 15 km. These areas have recently experienced tectonic activity that has weakened the lithosphere.

Description: The West Siberian Seaway connected the Tethys to the Arctic Ocean in the Paleogene and played an important role for Eurasian-Arctic biogeography, ocean circulation, and climate. However, the paleogeography and geological mechanisms enabling the seaway are not well constrained, which complicates linking the seaway evolution to paleoenvironmental changes. Here, we investigate the paleogeography of the Peri-Tethys realms for the Cenozoic time (66–0 Ma), including the West Siberian Seaway, and quantify the influence of mantle convection and corresponding dynamic topography. We start by generating continuous digital elevation models for Eurasia, Arabia, and Northern Africa, by digitizing regional paleogeographic maps and additional geological information and incorporate them in a global paleogeography model with nominal million-year resolution. Then we compute time-dependent dynamic topography for the same time interval and find a clear correlation between changes in dynamic topography and the paleogeographic evolution of Central Eurasia and the West Siberian Seaway. Our results suggest that mantle convection played a greater role in Eurasian paleogeography than previously recognized. Mantle flow may have influenced oceanic connections between the Arctic and global ocean providing a link between deep mantle convection, surface evolution, and environmental changes. Our reconstructions also indicate that the Arctic Ocean may have been isolated from the global ocean in the Eocene, even if the West Siberian Seaway was open, as the Peri-Tethys – Tethys connection was limited, and the Greenland-Scotland Ridge was a landbridge.

Description: This study introduces a new approach for in situ Rb–Sr dating that utilizes rapid line scans instead of static spot ablation, enabling the creation of two-dimensional 87Rb/86Sr and 87Sr/86Sr isotope ratio and Rb–Sr age maps. The data acquisition is conducted utilizing an ICP-MS/MS instrument with N2O as the reaction gas, coupled to a 193 nm excimer laser via a low-aerosol-dispersion interface. This configuration allows for high repetition rates (〉100 Hz) and sensitivities, enabling data acquisition at a high scanning speed and small laser beam size (3–4 μm). Notably, this approach requires just about 1/30 of the sample volume typically utilized in conventional spot ablation mode, while achieving similar levels of precision and accuracy. Line scan ablation is tested and compared to spot ablation on age-homogeneous crystalline muscovite and biotite, for which reference Rb–Sr age data is acquired through ID-TIMS. Results show that a key requirement for accurate Rb–Sr ages based on line scan analyses is matrix correction using chemically matched crystalline mica. By presenting Rb–Sr age maps of three naturally deformed mica samples, we highlight the potential of Rb–Sr mapping for extracting age data from rocks that exhibit complex metamorphic-metasomatic histories and microscale dynamic recrystallization. Additionally, we show that quantitative elemental information (Al, Fe, Si, Li) can be collected alongside Rb–Sr isotope data. This advancement offers a distinctly more insightful assessment of isotope mobility in natural systems, the timing of element enrichment processes and enables, in high-Rb/Sr rock systems, precise and accurate isotopic dating of intricate geological processes at small scales.

Description: High-resolution flood maps are needed for more effective flood risk assessment and management. Producing these directly with hydrodynamic models is slow and computationally prohibitive at large scales. Here we demonstrate a new algorithm for post-processing low-resolution inundation layers by using high-resolution terrain models to disaggregate or downscale. The new algorithm is roughly 8 times faster than state-of-the-art algorithms and shows a slight improvement in accuracy when evaluated against observations of a recent flood using standard performance metrics. Qualitatively, the algorithm generates more physically coherent flood maps in some hydraulically challenging regions compared to the state of the art. The algorithm developed here is open source and can be applied in conjunction with a low-resolution hydrodynamic model and a high-resolution DEM to rapidly produce high-resolution inundation maps. For example, in our case study with a river reach of 20 km, the proposed algorithm generated a 4 m resolution inundation map from 32 m hydrodynamic model outputs in 33 s compared to a 4 m hydrodynamic model runtime of 34 min. This 60-fold improvement in runtime is associated with a 25 % increase in RMSE when compared against the 4 m hydrodynamic model results and observations of a recent flood. Substituting downscaling into flood risk model chains for high-resolution modelling has the potential to drastically improve the efficiency of inundation map production and increase the lead time of impact-based forecasts, helping more at-risk communities prepare for and mitigate flood damages.

Description: To design user-centred and scientifically high-quality outreach products to inform about earthquake-related hazards and the associated risk, a close collaboration between the model developers and communication experts is needed. In this contribution, we present the communication strategy developed to support the public release of the first openly available European Seismic Risk Model and the updated European Seismic Hazard Model. The backbone of the strategy was the communication concept in which the overall vision, communication principles, target audiences (including personas), key messages, and products were defined. To fulfil the end-users' needs, we conducted two user testing surveys: one for the interactive risk map viewer and one for the risk poster with a special emphasis on the European earthquake risk map. To further ensure that the outreach products are not only understandable and attractive for different target groups but also adequate from a scientific point of view, a two-fold feedback mechanism involving experts in the field was implemented. Through a close collaboration with a network of communication specialists from other institutions supporting the release, additional feedback and exchange of knowledge was enabled. Our insights, gained as part of the release process, can support others in developing user-centred products reviewed by experts in the field to inform about hazard and risk models.

Description: Distributed Acoustic Sensing (DAS) is becoming a powerful tool for earthquake monitoring, providing continuous strain-rate records of seismic events along fiber optic cables. However, the use of standard seismological techniques for earthquake source characterization requires the conversion of data in ground motion quantities. In this study we provide a new formulation for far-field strain radiation emitted by a seismic rupture, which allows to directly analyze DAS data in their native physical quantity. This formulation naturally accounts for the complex directional sensitivity of the fiber to body waves and to the shallow layering beneath the cable. In this domain, we show that the spectral amplitude of the strain integral is related to the Fourier transform of the source time function, and its modeling allows to determine the source parameters. We demonstrate the validity of the technique on two case-studies, where source parameters are consistent with estimates from standard seismic instruments in magnitude range 2.0–4.3. When analyzing events from a 1-month DAS survey in Chile, moment-corner frequency distribution shows scale invariant stress drop estimates, with an average of Δσ = (0.8 ± 0.6) MPa. Analysis of DAS data acquired in the Southern Apennines shows a dominance of the local attenuation that masks the effective corner frequency of the events. After estimating the local attenuation coefficient, we were able to retrieve the corner frequencies for the largest magnitude events in the catalog. Overall, this approach shows the capability of DAS technology to depict the characteristic scales of seismic sources and the released moment.

Description: Large parts of the Earth’s interior are inaccessible to direct observation, yet global geodynamic processes are governed by the physical material properties under extreme pressure and temperature conditions. It is therefore essential to investigate the deep Earth’s physical properties through in-situ laboratory experiments. With this goal in mind, the optical properties of mantle minerals at high pressure offer a unique way to determine a variety of physical properties, in a straight-forward, reproducible, and time-effective manner, thus providing valuable insights into the physical processes of the deep Earth. This thesis focusses on the system Mg-Fe-O, specifically on the optical properties of periclase (MgO) and its iron-bearing variant ferropericlase ((Mg,Fe)O), forming a major planetary building block. The primary objective is to establish links between physical material properties and optical properties. In particular the spin transition in ferropericlase, the second-most abundant phase of the lower mantle, is known to change the physical material properties. Although the spin transition region likely extends down to the core-mantle boundary, the ef-fects of the mixed-spin state, where both high- and low-spin state are present, remains poorly constrained. In the studies presented herein, we show how optical properties are linked to physical properties such as electrical conductivity, radiative thermal conductivity and viscosity. We also show how the optical properties reveal changes in the chemical bonding. Furthermore, we unveil how the chemical bonding, the optical and other physical properties are affected by the iron spin transition. We find opposing trends in the pres-sure dependence of the refractive index of MgO and (Mg,Fe)O. From 1 atm to ~140 GPa, the refractive index of MgO decreases by ~2.4% from 1.737 to 1.696 (±0.017). In contrast, the refractive index of (Mg0.87Fe0.13)O (Fp13) and (Mg0.76Fe0.24)O (Fp24) ferropericlase increases with pressure, likely because Fe Fe interactions between adjacent iron sites hinder a strong decrease of polarizability, as it is observed with increasing density in the case of pure MgO. An analysis of the index dispersion in MgO (decreasing by ~23% from 1 atm to ~103 GPa) reflects a widening of the band gap from ~7.4 eV at 1 atm to ~8.5 (±0.6) eV at ~103 GPa. The index dispersion (between 550 and 870 nm) of Fp13 reveals a decrease by a factor of ~3 over the spin transition range (~44–100 GPa). We show that the electrical band gap of ferropericlase significantly widens up to ~4.7 eV in the mixed spin region, equivalent to an increase by a factor of ~1.7. We propose that this is due to a lower electron mobility between adjacent Fe2+ sites of opposite spin, explaining the previously observed low electrical conductivity in the mixed spin region. From the study of absorbance spectra in Fp13, we show an increasing covalency of the Fe-O bond with pressure for high-spin ferropericlase, whereas in the low-spin state a trend to a more ionic nature of the Fe-O bond is observed, indicating a bond weakening effect of the spin transition. We found that the spin transition is ultimately caused by both an increase of the ligand field-splitting energy and a decreasing spin-pairing energy of high-spin Fe2+.

Description: Geodynamische Prozesse werden von den physikalischen Materialeigenschaften unter den extremen Druck- und Temperaturbedingungen des Erdinneren gesteuert, gerade diese Areale sind aber faktisch nicht für direkte Beobachtungen zugänglich. Umso wichtiger ist es, die physikalischen Eigenschaften unter Bedingungen des Erdinneren zu untersuchen. Mit diesem Ziel vor Augen erlaubt das Studium der optischen Eigenschaften von Mineralen des Erdmantels, eine große Bandbreite an physikalischen Materialeigenschaften, in einer einfachen, reproduzierbaren und effizienten Art und Weise zu bestimmen. Dadurch bieten sich wichtige Einblicke in die physikalischen Prozessen des Erdinneren. Die vorliegende Arbeit konzentriert sich auf das System Mg-Fe-O, im Speziellen auf Periklas (MgO) und seine Eisen-haltige Variante Ferroperiklas ((Mg,Fe)O), ein wichtiger Baustein planetarer Körper. Das Hauptziel der Arbeit besteht darin Verbindungen zwischen optischen Eigenschaften und physikalischen Materialeigenschaften zu finden. Gerade der Spin-Übergang in Ferroperiklas, der zweithäufigsten Phase des unteren Erdmantels, ist dabei von Bedeutung, da damit Veränderungen in den physikalischen Materialeigenschaften einhergehen. Obwohl sich der Spinübergangsbereich vermutlich bis zur Kern-Mantel-Grenze erstreckt, sind die Auswirkungen des gemischten Spin-Zustandes, bei dem sowohl Hoch- als auch Tief-Spin präsent sind, nur unzureichend untersucht. Die hier vorgestellten Studien zeigen, wie optische Eigenschaften mit anderen wichtigen physikalischen Eigenschaften wie elektrischer und thermischer Leitfähigkeit, Viskosität oder auch mit der chemischen Bindung verbunden sind. Daraus lässt sich auch ableiten wie der Spin-Übergang in Ferroperiklas diese Eigenschaften beeinflusst. Von Raumbedingungen bis zu ~140 GPa sinkt der Brechungsindex von MgO um ~2.4 % von 1.737 auf 1.696 (±0.017). Im Gegensatz dazu steigt der Brechungsindex von (Mg0.87Fe0.13)O (Fp13) und (Mg0.76Fe0.24)O (Fp24) Ferroperiklas mit dem Druck an. Dies ist auf Fe-Fe Wechselwirkungen zwischen benachbarten Eisenpositionen zurückzuführen, die eine starke Verringerung der Polarisierbarkeit, wie im Falle von reinem MgO mit zunehmender Dichte, behindern. Eine Analyse der Dispersion des Brechungsindexes von MgO (Abnahme um ~23 % von 1 Atm zu ~103 GPa) offenbart eine Verbreiterung der Bandlücke von ~7.4 eV bei 1 Atm zu ~8.5 (±0.6) eV bei ~103 GPa. Die Messung der Dispersion (zwischen 550 und 870 nm) in Fp13 zeigt eine starke Abnahme über den Bereich des Spin-Überganges (~44–100 GPa) bis zu einem Faktor von ~3. Die Bandlücke nimmt in der Region des gemischten Spin-Zustandes signifikant auf bis zu ~4.7 eV zu (entspricht einer Zunahme um den Faktor ~1.7). Dies deutet auf eine Verringerung der Elektronen-Mobilität zwischen benachbarten Fe2+-Positionen mit unterschiedlichem Spin-Zustand hin, was die bereits in früheren Arbeiten beobachtete Abnahme der elektrischen Leitfähigkeit im Bereich des gemischten Spin-Zustandes erklärt. Absorptionsspektren an Fp13 zeigen eine Druck-bedingte Zunahme der Kovalenz der Fe-O Bindung für Ferroperiklas im Hoch-Spin Zustand, wohingegen Tief-Spin Ferroperiklas einen Trend zu einer mehr ionischen Fe-O Bindung auf-weist, was auf einen Bindungs-schwächenden Effekt des Spin-Wechsels hinweist. Der Übergang von Hoch- zu Tiefspin ist letztlich auf eine Zunahme der Ligandenfeldaufspaltungsenergie sowie eine abnehmende Spinpaarungsenergie von Hoch-Spin Fe2+ zurückzuführen.