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Thermally treated kaolinite is used to develop a range of alumino‐silicate‐based precursor materials but its behavior during plasma spraying has not been well‐researched. In this study, two types of kaolinite samples were investigated in the form of low defect (KGa‐1b) and high defect (KGa‐2) varieties. The extreme temperatures of the plasma stream (up to 20 000 K) induced flash melting to produce a highly porous alumino‐silicate glass without any crystallization of new Al−Si oxide minerals. The glass is comprised largely of intact or deformed spheres (average diameters 1.14–1.44 μm), which indicates rapid quenching and solidification before impact. The subspherical structures contain up to 40 % closed pore space caused by the rapid escape of water during melting. The low‐density, porous alumino‐silicate glass coatings with predicted specific surface areas (>0.95 m2/g) and hardnesses >1.8 GPa represent a potentially reactive but physically stable substrate ideal for further chemical functionalization.
Late Pleistocene glacitectonism at the southern Scandinavian Ice Sheet margin caused folding and thrusting of Upper Cretaceous chalk layers and Pleistocene glacial deposits in parts of the southwestern Baltic Sea area in Europe. Beside Møns Klint (SE Denmark), the Jasmund Glacitectonic Complex (JGC) on Rügen Island (NE Germany) is a similar striking example of glacitectonic deformation creating large composite ridges. In spite of a long research history and new results from modern datasets, the structural development of the JGC is still poorly understood, especially the detailed evolution of the southern JGC and its relationship to the northern JGC remain enigmatic. In this contribution, we demonstrate how the understanding of the JGC benefits from the application of established structural geological methods comprehending the formation of fold-and-thrust belts. The methods include cross-section balancing of the eastern coast (southern JGC) and quantification of the amount of folding and faulting. The proposed geometric model shows the current fold-and-thrust stack of glacially deformed sedimentary strata ca. 5720 m in length evolved by shortening from the original length (11,230 m) by 5510 m (49.1%). We present a spatial and temporal development of fault-related folding with a transition from detachment folds through fault-propagation folds to fault-bend folds. Together with morphological information from a digital elevation model, the thrust faults mapped in the cliff section are mainly inclined towards the S to SW and imply that a local glacier push occurred from the south. These results highlight the complexity and individual architecture of the JGC when compared to other Pleistocene and modern glacitectonic complexes. Resolving its structural development provides new insight into the deformation history and shortening of this spectacular glacitectonic complex lying in the southwestern Baltic Sea region.
There is a current need for developing improved synthetic porous materials for better constraining the dynamic and coupled processes relevant to the geotechnical use of underground reservoirs. In this study, a low temperature preparation method for making synthetic rocks is presented that uses a geopolymer binder cured at 80 °C based on alkali-activated metakaolin. For the synthesised sandstone, the key rock properties permeability, porosity, compressive strength, and mineralogical composition, are determined and compared against two natural reservoir rocks. In addition, the homogeneity of the material is analysed structurally by micro-computed tomography and high-resolution scanning electron microscopy, and chemically by energy dispersive X-ray spectroscopy. It is shown that simple, homogenous sandstone analogues can be prepared that show permeability-porosity values in the range of porous reservoir rocks. The advance in using geopolymer binders to prepare synthetic sandstones containing thermally sensitive minerals provides materials that can be easily adapted to specific experimental needs. The use of such material in flow-through experiments is expected to help bridge the gap between experimental observations and numerical simulations, leading to a more systematic understanding of the physio-chemical behaviour of porous reservoir rocks.
Calcitic valves of non-marine ostracodes are important geochemical archives. Investigations of the relationship between the ranges of oxygen and carbon isotope values of modern ostracode populations and their host water provide important information on local or regional conditions and influences. Here we present the first δ18Oostracode and δ13C of the freshwater ostracode species Cytheridella ilosvayi along with the isotopic composition of the waters in which the ostracodes calcified, δDwater, δ18Owater, δ13CDIC values—covering a large geographical range (Florida to Brazil). With this data we extended a newly developed approach based on the estimation of δ18O values of monthly equilibrium calcites as references for the interpretation of δ18Oostracode values. The expected apparent oxygen isotope fractionation between CaCO3 and H2O is correlated with temperature with smaller values occurring at higher temperatures as valid at isotope equilibrium (δ18Ocalcite_eq). Uncertainties about the expected equilibrium calcites derive from incomplete knowledge of high-frequency variations of the water bodies caused by interplay of mixing, evaporation, and temperature. Coincidence between δ18Oostracode and δ18Ocalcite_eq is restricted to few months indicating a seasonal calcification of Cytheridella. There is a characteristic pattern in its difference between mean δ18Oostracode and δ18Ocalcite_eq which implies that Cytheridella provides a synchronous life cycle in its geographical range with two calcification periods in spring (May, June) and autumn (October). This ubiquitous life cycle of Cytheridella in the entire study area is considered to be phylogenetically inherited. It might have originally been adapted to environmental conditions but has been conserved during the migration and radiation of the group over the Neotropical realm.
There is broad scientific consensus that current food systems are neither sustainable nor resilient: many agricultural practices are very resource-intensive and responsible for a large share of global emissions and loss of biodiversity. Consequently, current systems put large pressure on planetary boundaries. According to economic theory, food prices form when there is a balance between supply and demand. Yet, due to the neglect of negative external effects, effective prices are often far from representing the ‘true costs’. Current studies show that especially animal-based foodstuff entails vast external costs that currently stay unaccounted for in market prices. Against this background, we explore how informational campaigning on agricultural externalities can contribute to consumer awareness and tolerance of this matter. Further, we investigate the socially just design of monetary incentives and their implementation potentials and challenges. This study builds on the informational campaign of a German supermarket displaying products with two price tags: one of the current market price and the other displaying the ‘true’ price, which includes several environmental externalities calculated with True Cost Accounting (TCA). Based on interpretations of a consumer survey and a number of expert interviews, in this article we approach the potentials and obstacles of TCA as a communication tool and the challenges of its factual implementation in agri-food networks. Our results show that consumers are generally interested in the topic of true food pricing and would to a certain extent be willing to pay ‘true prices’ of the inquired foods. However, insufficient transparency and unjust distribution of wealth are feared to bring about communication and social justice concerns in the implementation of TCA. When introducing TCA into current discourse, it is therefore important to develop measures that are socially cautious and backed by relevant legal framework conditions. This poses the chance to create a fair playing (‘polluter pays’) with a clear assignment of responsibilities to policy makers, and practitioners in addition to customers.
Circular economies are an important pillar of sustainable production and consumption. This particularly applies to the agri-food industry, which is characterised by large amounts of organic waste and by-product streams posing a serious challenge for many food producers. Therefore, respective firms increasingly adopt circular economy business models (CEBMs) to manage these resource flows effectively. However, there is only little knowledge on the functioning of CEBMs in bio-based industries, especially from a socio-economic perspective. We address this gap by exploring enablers and motivations behind such business models as well as the institutional contexts they are embedded in. In methodological terms, we adopt a case study approach using the example of potato production in Lower Saxony (northwest Germany). The core of the paper is a qualitative in-depth analysis of four potato processors, adopting varying business models to valorise their by-product streams (e.g. peels, scraps, pulp) either ‘in-house’ or in partnerships with external partners. The findings show that the implementation of CEBMs results from a complex interplay of internal and external enablers, with economic considerations as the main impetus for the management of biological reverse cycles. Thereby, we found a shifting economic logic in the assessment of potato by-products from disposable waste to valuable resources for other sectors (e.g. livestock farming, bioenergy, biofuels). While being encouraged by targeted policies, the companies studied feel increasingly affected by emerging sustainability discourses, prompting them to (re)design and (re)frame their CEBMs in view of environmental and societal issues.
Thyreophora is a clade of globally distributed herbivorous ornithischian dinosaurs. The earliest forms are known from the Early Jurassic, and their latest surviving representatives witnessed the end-Cretaceous mass extinction. Throughout their evolutionary history, these ‘shield bearers’ became lumbering quadrupeds, evolved a wide array of bony armor, plates and spikes, as well as sweeping tail weapons in the form of tail clubs and thagomizers. An isolated new thyreophoran osteoderm from a Lower Jurassic Konservatlagerstätte near Grimmen is described and, with the aid of micro-CT data, compared to an osteoderm of the early diverging thyreophoran Emausaurus ernsti from a different stratigraphic horizon at the same locality.
Diagenetic illite growth in porous sandstones leads to significant modifications of the initial pore system which result in tight reservoirs. Understanding and quantifying these changes provides insight into the porosity-permeability history of the reservoir and improves predictions on petrophysical behavior. To characterize the various stages of diagenetic alteration, a focused ion beam – scanning electron microscopy (FIB-SEM) study was undertaken on aeolian sandstones from the Bebertal outcrop of the Parchim Formation (Early Permian Upper Rotliegend group). Based on 3D microscopic reconstructions, three different textural types of illite crystals occur, common to many tight Rotliegend sandstones, namely (1) feldspar grain alterations and associated illite meshworks, (2) tangential grain coats, and (3) pore-filling laths and fibers. Reaction textures, pore structure quantifications, and numerical simulations of fluid transport have revealed that different generations of nano-porosity are connected to the diagenetic alteration of feldspars and the authigenic growth of pore-filling illites. The latter leads to the formation of microstructures that range from authigenic compact tangential grain coatings to highly porous, pore-filling structures. K-feldspar replacement and initial grain coatings of illite are composed primarily of disordered 1Md illite whereas the epitaxially grown illite lath- and fiber-shaped crystals occurring as pore-filling structures are of the trans-vacant 1Mtv polytype. Although all analyzed 3D structures offer connected pathways, the largest reduction in sandstone permeability occurred during the initial formation of the tangential illite coatings that sealed altered feldspars and the subsequent growth of pore-filling laths and fibrous illites. Analyses of both illite pore-size and crystallite-size distributions indicate that crystal growth occurred by a continuous nucleation and growth mechanism probably controlled by the multiple influx of potassium-rich fluids during late Triassic and Jurassic times. The detailed insight into the textural varieties of illite crystal growth and its calculated permeabilities provides important constraints for understanding the complexities of fluid-flow in tight reservoir sandstones.
Ocean literacies: the promise of regional approaches integrating ocean histories and psychologies
(2023)
The current concept of ocean literacy reflects a prerequisite for achieving ocean sustainability. Existing ocean literacy reflects a fundamentally western view of oceans that works in tension with ocean literacy goals. Although ocean literacy practitioners and researchers are, laudably, starting to incorporate Indigenous knowledges and perspectives from BIPOC communities, attention to historical change continues to be left out of ocean literacy, to the detriment of ocean literacy goals. This article points out that, given the reality that human-ocean relationships have changed over time, and differed among cultural groups in the past as well as in the present, ocean literacy needs to incorporate ocean history at a foundational level. Because there are historical differences in human relationships with oceans, it stands to reason that regional ocean literacies must be more effective than a universal and timeless ocean literacy framework. Following the logical efficacy of a regional approach to ocean literacy, this article further argues that regional ocean literacies should involve the systematic inclusion of emotional elements. Regional ocean literacies should be constructed through knowledge co-production, involving diverse types of expertise, knowledge and actors to produce context-specific knowledge and pathways towards a sustainable future. To fully exploit the potential of ocean literacy, there is a need for the UN Ocean Decade to work towards regional and place-based approaches that incorporate history as well as culture in an iterative and collaborative process involving diverse types of expertise, knowledge and actors.
Giant clam (Tridacna) distribution in the Gulf of Oman in relation to past and future climate
(2022)
The Oman upwelling zone (OUZ) creates an unfavorable environment and a major biogeographic barrier for many coral reef species, such as giant clams, thus promoting and maintaining faunal differences among reefs on the east and west side of the Arabian Peninsula. We record the former existence of Tridacna in the Gulf of Oman and review its stratigraphic distribution in the Persian Gulf to provide new insights on the connectivity of coral reef habitats around southern Arabia under changing climate and ocean conditions. Fossil shells were carbon-14 dated and employed as sclerochronological proxy archives. This reveals that the Omani population represents a last glacial colonization event during the Marine Isotope Stage 3 interstadial under colder-than-present temperatures and variable upwelling intensity linked to Dansgaard-Oeschger climate oscillations. It was favored by temperatures just above the lower threshold for the habitat-forming reef coral communities and instability of the upwelling barrier. We conclude that the distribution of Tridacna in the northern Arabian Sea is generally limited by either strong upwelling or cool sea surface temperature under gradually changing climate conditions at the interglacial-glacial scale. Opportunities for dispersal and temporary colonization existed only when there was a simultaneous attenuation of both limiting factors due to high-frequency climate variability. The OUZ will unlikely become a future climate change refuge for giant clams because they will be exposed either to thermal stress by rapid anthropogenic Indian Ocean warming or to unfavorable upwelling conditions.