ALBERT

Beschreibung: Natural gas hydrates form at elevated pressure and low temperatures in the presence of sufficient quantities of gas and water and have therefore been discovered on all continental margins and in permafrost regions. In the marine hydrate-bearing sediments, gas hydrates, depending on their content, can transform a loose sediment into a consolidated rock with a strongly increased strength. In permafrost regions the hydrate stability zone can extent deep into the ice-bearing permafrost and, therefore, both, ice and hydrate can consolidate the sediment. However, the strength of methane hydrate is much higher than that of ice, which behaves much more ductile. Consequently, the resulting strength of a sediment, containing both components, strongly depends on the ice to hydrate ratio. Conversely, the decomposition of natural gas hydrates in marine or permafrost sediments leads to a reduction in the mechanical strength of the host sediment. In addition, the release of gas can create overpressure in the pore spaces, reducing the effective stress and leading to instabilities in the sediment structure. Since both continental margins and permafrost regions are used by humans for various activities that largely depend on the mechanical stability of the sediments, knowledge of the main factors and processes that determine the stability of weakly consolidated sediments is crucial. Both the thawing of ice and the decomposition of gas hydrates in permafrost soils lead to a change in the geo-mechanical properties of the host sediment. The residual and peak shear strengths of ice- and hydrate-bearing sediments were investigated using a ring shear cell developed at the GFZ. Based on literature data and our results, we discuss the dependence of the geo-mechanical properties of sediments on ice and hydrate saturation and the possible consequences if their proportion diminishes.

Beschreibung: Natural gas hydrates are crystalline compounds that are formed from hydrogen-bonded water molecules and gas molecules. They mainly contain climate-active CH4, but also other light hydrocarbons, CO2 or H2S They exhibit a high sensitivity to variations in temperature and pressure, mainly driven by environmental changes. The oceanic or atmospheric warming resulting from climate change may trigger the decompositions of hydrates, potentially releasing significant amounts of CH4. To assess the potential risks associated with CH4 release from destabilized hydrate deposits, a precise understanding of the dissociation behaviour of gas hydrates becomes crucial. In this study, a systematic investigation on the dissociation process of sI CH4 hydrates, sII CH4+C3H8 hydrates, and sII multi-component CH4+C2H6+C3H8+CO2 mixed hydrates was reported. We employed a combination of experimental and molecular dynamics (MD) simulations to provide a more nuanced understanding of the hydrate dissociation behaviours, which primarily shed light on the molecular aspects. The dissociation was induced through thermal stimulation to mimic climate warming. Both in situ and ex situ Raman spectroscopic measurements were performed continuously to characterize the hydrate phase. Throughout the dissociation process, hydrate composition, surface morphology, and the large-to-small cavity ratios were determined. MD simulations were carried out under similar conditions, providing advanced insights and perspectives that couldn't be readily extracted from experimental observations alone. Both experimental and simulation outcomes indicate that intrinsic kinetics likely govern the early stage of hydrate dissociation. A significant development in the dissociation process is the hindrance caused by the formation of a quasi-liquid or amorphous phase at the surface of the hydrate particles after the breakup of the outer layer of hydrate cavities. The unstable (partial) hydrate cavities that form within this quasi-liquid phase are oversaturated with gas molecules. Consequently, gas hydrates undergo a cycle of decomposition-reformation-continuing decomposition until the crystal eventually disappears. With decomposition dominating the process, both experimental and numerical simulation results demonstrate that the breakup of large cavities (51262) is faster than that of small ones (512) in sI hydrates. Conversely, a faster breakdown of small 512 cavities in sII hydrates is observed. Additionally, during the dissociation process of sII CH4-C3H8 hydrate, the cavities occupied by CH4 preferentially collapse compared to those filled with C3H8. Similarly, over the dissociation of multi-component hydrate, cavities filled with CH4 exhibit a preferential collapse compared to those filled with C3H8, C2H6, and CO2. These findings show the complexity and differences in the dissociation behavior of natural gas hydrates depending on their composition and structure and can therefore make an important contribution to an accurate assessment of CH4 release from destabilized hydrate deposits in response to climate change.

Beschreibung: This dataset is the result of an experimental series that was carried out in September/October 2022 at GFZ German Research Centre for Geosciences, Potsdam, Germany to observe biosorption of lead under extreme conditions. Synthetic solutions, simulating the geothermal fluids from the Heemskerk geothermal power plant were were prepared in 30 ml glass vials (Rotalibo screw neck ND24 EPA). To prepare the stock solutions, sodium chloride (NaCl, 99.8 %, Cellpure, Merck, DE) was added at 265 g/L and Pb(II), in form of lead nitrate (Pb(NO3 )2 , Merck, DE), at 1 g/L to ultrapure water. To assess the impact of acetic acid on lead biosorption, two treatments were done: one without acetic acid and one where acetic acid (100 %, Merck, DE) was added at 60 mg/L. Finally, dead biomass of the fungus Penicillium citrinum was added in the samples at a concentration of 4 g/L (Wahab et al., 2017). The samples were incubated in an autoclave at a pressure of 8 bars on a rotative shaker. The temperature was set at 25 °C, 60 °C or 98 °C with three contact times (1, 2 and 3 h). All treatments were performed in triplicates. For each treatment, two controls without biomass were done. Control samples without the addition of NaCl were done in duplicate, at 25 °C and for 2 h. After incubation, samples were filtered through a 0.22 µm nitrocellulose filter (Sartorius Stedim Biotech, FR) to separate the biomass from the liquid. The biomass on the filters was dried for 24 h at 45 °C before being scraped from the filter and kept in a Falcon tube at room temperature.

Beschreibung: 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).

Beschreibung: We study the impact of recent global warming on extreme climatic events in Central Asia (CA) for 1901-2019 by comparing the composite representation of the observational climate with a hypothetical counterfactual one that does not include the long-term global warming trend. The counterfactual climate data are produced based on a simple detrending approach, using the global mean temperature (GMT) as the independent variable and removing the long-term trends from the climate variables of the observational data. This trend elimination is independent of causality, and the day-to-day variability in the counterfactual climate remains preserved. The analysis done in the paper shows that the increase in frequency and magnitude of extreme temperature and precipitation events can be attributed to global warming. Specifically, the probability of experiencing a +7 K temperature anomaly event in CA increases by up to a factor of seven in some areas due to global warming. The analysis reveals a significant increase in heatwave occurrences in Central Asia, with the observational climate dataset GSWP3-W5E5 (later called also factual) showing more frequent and prolonged extreme heat events than hypothetical scenarios without global warming. This trend, evident in the disparity between factual and counterfactual data, underscores the critical impact of recent climatic changes on weather patterns, highlighting the urgent need for robust adaptation and mitigation strategies. Additionally, using the self-calibrated Palmer drought severity index (scPDSI), the sensitivity of dry and wet events to the coupled precipitation and temperature changes is analyzed. The areas under dry and wet conditions are enhanced under the observational climate compared to a counterfactual scenario, especially over the largest deserts in CA. The expansion of the dry regions aligns well with the pattern of desert development observed in CA in recent decades.

Beschreibung: This study investigates the attribution of climate change to trends in river discharge during six decades from 1955 until 2014 in 12 selected river catchments across six Central Asian countries located upstream of the main rivers. For this purpose, the semi-distributed eco-hydrological model SWIM (Soil and Water Integrated Model) was firstly calibrated and validated for all study catchments. Attributing climate change to streamflow simulation trends was forced by factual (reanalysis) and counterfactual climate data (assuming the absence of anthropogenic influence) proposed in the framework of the ISIMIP (Inter-Sectoral Impact Model Intercomparison Project) or ESM without anthropogenic forcing that were firstly tested and then compared. The trend analysis was performed for three variables: mean annual discharge and high flow (Q5) and low flow (Q95) indices. The results show that trends in the annual and seasonal discharge could be attributed to climate change for some of the studied catchments. In the three northern catchments (Derkul, Shagan, and Tobol), there are positive trends, and in two catchments (Sarysu and Kafirnigan), there are negative streamflow trends under the factual climate, which could be attributed to climate change. Also, our analysis shows that the average level of discharge in Murghab has increased during the historical study period due to climate change, despite the overall decreasing trend during this period. In addition, the study reveals a clear signal of shifting spring streamflow peaks in all catchments across the study area.

Beschreibung: The papers in this volume were presented at the 47th Annual Conference on African Linguistics at UC Berkeley in 2016. The papers offer new descriptions of African languages and propose novel theoretical analyses of them. The contributions span topics in phonetics, phonology, syntax, semantics, and pragmatics and reflect the typological and genetic diversity of languages in Africa. Four papers in the volume examine Areal Features and Linguistic Reconstruction in Africa, and were presented at a special workshop on this topic held alongside the general session of ACAL.

Beschreibung: This study offers a new perspective on unusual and unsettling experiences that are often interpreted as “mental illnesses” and on the techniques through which literary representations invite readerly responses and engagement. The book examines how four Finnish modernist writers, Helvi Hämäläinen, Jorma Korpela, Timo K. Mukka, and Maria Vaara, construct experiences of shattering and distress as bodily experiences that are embedded in the social and material world and entangled with social and cultural norms that govern subjectivity, gender, and sexuality. Drawing on narrative theory, theories of embodied cognition, phenomenology of illness, and feminist theory, the analyses show how literary works can invite readers to respond emotionally and to reflect on our views of the human mind and its interaction with the world. The book sheds light on the fictional portrayals and techniques of representation and on the ethics of narrating and reading about painful experiences. It also illuminates the ways the mind, body, consciousness, and mental distress are discussed in Finnish modernist literature and situates the texts in the international modernist tradition.

Beschreibung: World of Warcraft rapidly became one of the most popular online world games on the planet, amassing 11.5 million subscribers—officially making it an online community of gamers that had more inhabitants than the state of Ohio and was almost twice as populous as Scotland. It's a massively multiplayer online game, or MMO in gamer jargon, where each person controls a single character inside a virtual world, interacting with other people's characters and computer-controlled monsters, quest-givers, and merchants. In My Life as a Night Elf Priest, Bonnie Nardi, a well-known ethnographer who has published extensively on how theories of what we do intersect with how we adopt and use technology, compiles more than three years of participatory research in Warcraft play and culture in the United States and China into this field study of player behavior and activity. She introduces us to her research strategy and the history, structure, and culture of Warcraft; argues for applying activity theory and theories of aesthetic experience to the study of gaming and play; and educates us on issues of gender, culture, and addiction as part of the play experience. Nardi paints a compelling portrait of what drives online gamers both in this country and in China, where she spent a month studying players in Internet cafes. Bonnie Nardi has given us a fresh look not only at World of Warcraft but at the field of game studies as a whole. One of the first in-depth studies of a game that has become an icon of digital culture, My Life as a Night Elf Priest will capture the interest of both the gamer and the ethnographer.