ALBERT

Description: Structure I methane hydrates are formed in situ from water-in-mineral oil emulsions in a high pressure rheometer cell. Viscosity is measured as hydrates form, grow, change under flow, and dissociate. Experiments are performed at varying water volume fraction in the original emulsion (0–0.40), temperature (0–6 °C), and initial pressure of methane (750–1500 psig). Hydrate slurries exhibit a sharp increase in viscosity upon hydrate formation, followed by complex behavior dictated by factors including continued hydrate formation, shear alignment, methane depletion/dissolution, aggregate formation, and capillary bridging. Hydrate slurries possess a yield stress and are shear-thinning fluids, which are described by the Cross model. Hydrate slurry viscosity and yield stress increased with increasing water volume fraction. As driving force for hydrate formation decreases (increasing temperature, decreasing pressure), hydrate slurry viscosity increases, suggesting that slower hydrate formation leads to larger and more porous aggregates. In total, addition of water to a methane saturated oil can cause more than a fifty-fold increase in viscosity if hydrates form.

Description: The discharges from industrial processes constitute the main source of copper contamination in aqueous ecosystems. In this study we investigated the capacity of different types of biochar (derived from chicken manure, eucalyptus, corncob, olive mill and pine sawdust) to remove copper from aqueous solution in a continuous-flow system. The flow rate of the system strongly influenced the amount of copper retained. The adsorption to the corncob biochar varied from 5.51 to 3.48 mg Cu g-1 as the flux decreased from 13 to 2.5 mL min-1. The physicochemical characteristics of biochar determine the copper retention capacity and the underlying immobilization mechanisms. Biochars with high inorganic contents retain the largest amounts of copper and may be suitable for using in water treatment systems to remove heavy metals. The copper retention capacity of the biochars ranged between ~1.3 and 26 mg g-1 and varied in the following order: chicken manure 〉 olive mill 〉〉 corncob 〉 eucalyptus 〉 sawdust pine.

Description: Innate immunity is the front line of self-defense against microbial infection. After searching for natural substances that regulate innate immunity using an ex vivo Drosophila culture system, we identified a novel dimeric chromanone, gonytolide A, as an innate immune promoter from the fungus Gonytrichum sp. along with gonytolides B and C. Gonytolide A also increased TNF-α-stimulated production of IL-8 in human umbilical vein endothelial cells.

Description: The majority of methane produced in many anoxic sediments is released via ebullition. These bubbles are subject to dissolution as they rise, and dissolution rates are strongly influenced by bubble size. Current understanding of natural methane bubble size distributions is limited by the difficulty in measuring bubble sizes over wide spatial or temporal scales. Our custom optical bubble size sensors recorded bubble sizes and release timing at 8 locations in Upper Mystic Lake, MA continuously for 3 months. Bubble size distributions were spatially heterogeneous even over relatively small areas experiencing similar flux, suggesting that localized sediment conditions are important to controlling bubble size. There was no change in bubble size distributions over the 3 month sampling period, but mean bubble size was positively correlated with daily ebullition flux. Bubble data was used to verify the performance of a widely used bubble dissolution model, and the model was then used to estimate that bubble dissolution accounts for approximately 10% of methane accumulated in the hypolimnion during summer stratification, and at most 15% of the diffusive air–water–methane flux from the epilimnion.

Description: Laboratory sediment incubations and continuous ebullition monitoring over an annual cycle in the temperate Saar River, Germany confirm that impounded river zones can produce and emit methane at high rates (7 to 30 (g CH4 m–3 d–1) at 25 °C and 270 to 700 (g CH4 m–2 yr–1), respectively). Summer methane ebullition (ME) peaks were a factor of 4 to 10 times the winter minima, and sediment methane formation was dominated by the upper sediment (depths of 0.14 to 0.2 m). The key driver of the seasonal ME dynamics was temperature. An empirical model relating methane formation to temperature and sediment depth, derived from the laboratory incubations, reproduced the measured daily ebullition from winter to midsummer, although late summer and autumn simulated ME exceeded the observed ME. A possible explanation for this was substrate limitation. We recommend measurements of methanogenically available carbon sources to identify substrate limitation and help characterize variation in methane formation with depth and from site to site.

Description: Microplastics (MPs, 〈5 mm) have been reported as emerging environmental contaminants, but reliable data are still lacking. We compared the two most promising techniques for MP analysis, namely, Raman and Fourier transform infrared (FTIR) spectroscopy, by analyzing MPs extracted from North Sea surface waters. Microplastics 〉500 μm were visually sorted and manually analyzed by μ-Raman and attenuated total reflection (ATR)-FTIR spectroscopy. Microplastics ≤500 μm were concentrated on gold-coated filters and analyzed by automated single-particle exploration coupled to μ-Raman (ASPEx-μ-Raman) and FTIR imaging (reflection mode). The number of identified MPs 〉500 μm was slightly higher for μ-Raman (+23%) than ATR-FTIR analysis. Concerning MPs ≤500 μm, ASPEx-μ-Raman quantified two-times higher MP numbers but required a four-times higher analysis time compared to FTIR imaging. Because ASPEx-μ-Raman revealed far higher MP concentrations (38–2621 particles m–3) compared to the results of previous water studies (0–559 particles m–3), the environmental concentration of MPs ≤500 μm may have been underestimated until now. This may be attributed to the exceptional increase in concentration with decreasing MP size found in this work. Our results demonstrate the need for further research to enable time-efficient routine application of ASPEx-μ-Raman for reliable MP counting down to 1 μm.

Description: The cage occupancy plays a crucial role in the thermodynamic stability of clathrate hydrates and is an important quantity for understanding the CO2–CH4 replacement phenomenon. In this work, the occupancy isotherms of pure CH4, pure CO2, and their mixture in sI and sII hydrates are studied by GCMC + MD simulations. The adsorption of CH4 and CO2 + CH4 in the sI and sII hydrates can be categorized as the one-site Langmuir type. The calculated occupancy ratio θL/θS and the abundance ratio of CO2 to CH4 vary with the temperature and pressure, which provide the prerequisite information for the prediction of CH4 recovery yield at different conditions in the CO2–CH4 gas exchange process. The phase equilibria of clathrate hydrates of pure gases and mixtures are explored and the corresponding heat of dissociation and hydration numbers are determined. The current investigation provides new perspectives to understand the mechanism behind the gas adsorption behavior of clathrate hydrates.

Description: Marine Ökosysteme wie Mangrovenwälder, Seegraswiesen, Salzwiesen und Makroalgen sowie marine Sedimente verfügen über die Eigenschaft, Kohlenstoff in ihrer Biomasse und Sedimenten zu speichern. Durch die Rehabilitation, Wiederherstellung und den Schutz dieser Ökosysteme kann somit das Potential des Ozeans zur Aufnahme von atmosphärischem CO2 erhöht werden. Dieses Potential wurde in Vorbereitung der 15. UN-Klimakonferenz in Kopenhagen 2009 unter dem Konzept „Blue Carbon" eingeführt und wird seitdem weiter erforscht und in politischen Prozessen weiterentwickelt. Die langfristige Sequestrierung von atmosphärischem CO2 durch Blue-Carbon-Ökosysteme unterstützt Umsetzungsprozesse zur Erreichung der Ziele des Pariser Abkommens. Das über Blue-Carbon-Ökosysteme sequestrierte CO2 zählt als Teil der globalen Kohlenstoffsenke als „negative Emissionen". So erreichte negative Emissionen sollten jedoch nicht zur Umgehung von ohnehin notwendigen politischen und wirtschaftlichen Schritten in Richtung einer CO2-neutralen Zukunft führen. Die Wiederherstellung und Rehabilitation von Blue-Carbon-Ökosystemen zur Erhöhung der natürlichen Kohlenstoffsenke des Planeten sollte zusätzlich zu einer signifikanten globalen Emissionsreduktion eingesetzt werden. Diese Studie erörtert die wissenschaftlichen, ökonomischen und politischen Fortschritte im Bereich Blue Carbon und stellt mögliche politische Handlungspfade vor, die das Potential von Blue-Carbon-Ökosystemen zum Klimaschutz in, durch und mit Deutschland stärken. Für die verschiedenen Blue-Carbon-Ökosysteme wird aufgezeigt, inwiefern die Ausweitung und der Schutz dieser Ökosystemen weitere Ziele der Klimaanpassung und der nachhaltigen Entwicklung unterstützen. Aufbauend auf einer Auswertung praktischer Umsetzungsbeispiele von Blue-Carbon-Projekten und möglicher Finanzierungsmechanismen wird nachfolgend ein politischer Handlungsleitpfaden für Deutschland in Bezug auf Blue Carbon entwickelt. Die politischen Handlungsempfehlungen wurden gemeinsam mit dem Bundesministerium für Umwelt, Naturschutz und Nukleare Sicherheit entwickelt.

Description: Marine ecosystems like mangroves forests, seagrass meadows, salt marshes and macroalgae can store carbon in their biomass and sediments. Rehabilitation, restoration and conservation of these ecosystems can increase the potential for atmospheric carbon uptake by the ocean. This concept was first introduced as ‘blue carbon’ during the preparation for the 15th UN Climate Change Conference in Copenhagen in 2009 and since then it has seen continuous incorporation into politics and research. The long-term sequestration of atmospheric CO2 via blue carbon ecosystems supports the 1.5°C goal of the Paris Agreement. The CO2 that is sequestered by blue carbon ecosystems is part of the global carbon sink and therefore it can be counted as ‘negative emissions’ in the global carbon stocktake. However, such negative emissions should not be implemented as a substitute for necessary political and economic measures towards a carbon neutral future. Rehabilitation and restoration of blue carbon ecosystems as a natural carbon sink is one of many measures but cannot replace the significant reduction of global emissions needed for the realisation of the global climate targets. This study discusses the scientific, economic and political realm of blue carbon. Furthermore, possible courses for political action “in”, “by”, and “through” Germany that could strengthen the potential of blue carbon ecosystems to sequester carbon are explored. The study investigates a variety of blue carbon ecosystems to determine to what extent the expansion and conservation of blue carbon ecosystems can support additional climate adaptation targets and Sustainable Development Goals. The evaluation of a multitude of implemented and ongoing blue carbon projects across the globe gives insight to best practices and possible financing mechanisms. A political guideline for Germany regarding blue carbon was developed together with the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

Description: Carbon dioxide (CO2) is a fundamental component of all life on Earth. Due to the considerable increase in emissions, particularly industrial emissions, CO2has, however, become a waste product and greenhouse gas damaging to the climate and, consequently, a threat to both humanity and nature. For almost 50years, chemical research has been pursuing the idea of making the CO2 molecule useful as a raw material(Aresta and Dibenedetto 2010). Within the context of the oil crises of the 1970s, and contingent on the currentneed for climate protection, there has been a rise in global interest in the research and development oftechnologies which could make CO2 useful as a source of carbon. Several regions in Europe, but also in North America and Asia have started sponsorship programmes to support the development of such technologies (BMBF 2014, Climate-KIC 2014, U.S. Department of Energy [DOE] n.d.).The goal of these efforts is to integrate this climatedamaging gas in extremely diverse industrial productionprocesses as a raw material. The use of CO2 would not only allow for the production of useful raw materials and products, such technologies could alsoemulate a natural carbon cycle (Peters et al. 2011). At the same time, they have the potential to reduce the consumption of other fossil resources and, in so doing, they might not only contribute to the extension of the resource base, but also reduce missionswhilst providing protection for natural resources (von der Assen et al. 2013). Technological breakthroughs and advancements are currently observedin carbon capture technologies in the catalysis and transformation of CO2 (Aresta 2010, Mikkelsen et al. 2010, Peters et al. 2011, Styring et al. 2011, Wilcox 2012, Smit et al. 2014, Klankermayer and Leitner 2015), and the first innovative CO2-based productsare already coming onto the markets.