ALBERT

Description: Global population projections foresee the biggest increase to occur in Africa with most of the available uncultivated land to ensure food security remaining on the continent. Simultaneously, greenhouse gas emissions are expected to rise due to ongoing land use change, industrialisation, and transport amongst other reasons with Africa becoming a major emitter of greenhouse gases globally. However, distinct knowledge on greenhouse gas emissions sources and sinks as well as their variability remains largely unknown caused by its vast size and diversity and an according lack of observations across the continent. Thus, an environmental research infrastructure—as being setup in other regions—is more needed than ever. Here, we present the results of a design study that developed a blueprint for establishing such an environmental research infrastructure in Africa. The blueprint comprises an inventory of already existing observations, the spatial disaggregation of locations that will enable to reduce the uncertainty in climate forcing’s in Africa and globally as well as an overall estimated cost for such an endeavour of about 550 M€ over the next 30 years. We further highlight the importance of the development of an e-infrastructure, the necessity for capacity development and the inclusion of all stakeholders to ensure African ownership.

Description: The oceans' role in climate and climate change is manifold. The Ocean circulation transports large amounts of heat and freshwater on hemispheric space scales which have significant impacts on regional climate in the ocean itself but also noticeable consequences via atmospheric teleconnections on land. Due to the high heat capacity of seawater and the relatively slow ocean circulation, the oceans provide a significant “memory” for the climate system. Bodies of water that descend from the sea surface may reside in the ocean interior for decades and centuries, while preserving their temperature and salinity signature, before they surface again to interact with the overlying atmosphere. The residence time of water in the atmosphere is about ten days and the persistence of dynamical states of the atmospheric circulation may last up to a few weeks. Thus, on long time scales ocean dynamics becomes important for climate, which implies that climate variations and climate change can only partially be understood without consideration of ocean dynamics and the intricate ocean-atmosphere interaction. Since 1960 the heat uptake of the oceans has been 20 times larger than that of the atmosphere. Thus the oceans have been able to reduce the otherwise much more pronounced temperature rise in the atmospheric climate. Also, over the last 200 years the oceans have absorbed about half of the CO2 release into the atmosphere by human activities (fossil fuel combustion, de-forestation, cement production), thereby reducing the direct effect of greenhouse gases on atmospheric temperatures.This chapter aims to describe and explain fundamental principles of the ocean dynamics and gathers information about past, present and future states the world’s ocean and its role in climate change.

Description: The Black Sea has undergone several limnic and marine stages due to fluctuations in the global sea level. The exchange of saline water from the Mediterranean Sea to the Black Sea through the Bosporus Strait was interrupted when the sea level dropped below the Bosporus sill. This induced limnic conditions, while marine conditions were established after the reconnection to saline Mediterranean seawater. Extended river fan systems developed during sea level low-stands, providing large amounts of organic material being buried by rapid sedimentation on the slopes of the Black Sea margins. The biogenic degradation of this material produces most of the methane gas expelled into the anoxic water column today. This largely happens by ubiquitous cold vents at ~700 m water depth (i.e. at the stability boundary of methane hydrates) and by mud volcanoes in ~2000 m water depth. A significant amount of gas is expected to accumulate in the sediment within the methane hydrate stability zone. However, bottom-simulating reflectors, the seismic indicator for gas hydrates, are not found everywhere along the margin. Recent analyses of the Danube and Dniepr fans have revealed a discontinuous gas hydrate formation in an area with no active seeps, while areas of active seepage located in the vicinity of BSR reflections held no gas hydrates. In addition, the ongoing diffusion of salt into the uppermost Black Sea sediment pore space since the last glacial maximum further reduces the volume of the gas hydrate stability zone. Estimates of the total amount of gas stored in gas hydrates therefore require a detailed structural analysis prior to regional- or basin-scale modelling attempts.

Description: The Q10 temperature coefficient, which is widely used in scientific literature, is a measure of the temperature sensitivity of chemical reaction rates or biological processes. However, the conclusions drawn from applying this coefficient to experimental data obtained from biological processes are not universal. In many biological processes, Q10 values are often discordant with the results predicted by the Arrhenius law. The hypothesis tested in the present study is that this problem arises mainly from the fact that the Q10 coefficient is defined by the ratio between rates described by exponential laws instead of power laws. Considering this hypothesis and the need to review the mathematical laws and models currently used to describe rates and Q10 coefficients, we propose a model beyond the usual Arrhenius theory or exponential decay law herein. The proposed mathematical model is based on the theory of deformed exponential functions, with the ordinary Q10 model representing the conventional exponential function. Therefore, all results following the standard model remain valid. Moreover, we include a Q10 free open-source code, written in Python, and compatible with Windows, Linux and macOS platforms. The validation of the proposed model and confirmation of the given hypothesis were performed based on the following temperature-dependent biological processes: soil organic carbon (SOC) decomposition (which is essential to forecast the impact of climate change on terrestrial ecosystems); the metabolism of Arctic zooplankton; physiological processes of the respiratory and cardiovascular systems; rate of oxygen consumption in mitochondria of the eurythermal killifish Fundulus heteroclitus, and leaf respiration.

Description: Highlights • Continuous CH4 bioelectrosynthesis from CO2 demonstrated with 80% or higher Coulombic Efficiency • At pH values below 8 CH4 cathodic off-gas contains up to 85% CH4 • At pH above 8.5, production of acetate and then ethanol (up to 8 g L−1) was obtained • Coulombic efficiency remained above 80% • 16S sequencing showed proliferation of Clostridium, Methanosaeta, Methanobrevibacter and Methanobacterium spp at the cathode This study demonstrates the continuous conversion of CO2 to methane, acetate, and ethanol in a Microbial Electrosynthesis Cell (MESC) with a carbon felt biocathode. The MESC was inoculated with a mixed anaerobic microbial consortium and operated at a mesophilic temperature of 30 °C. In situ deposition of Ni and Fe was achieved by introducing 0.2 g L−1 of NiSO4 or FeSO4, respectively, into the cathode compartment influent stream. In response, a considerable improvement in MESC performance was observed with a current density of 6.4 mA cm−2 (per separator area) and a CH4 production of 0.83 L (LR d)−1 (R = cathode volume). Once Ni and Fe were removed from the influent solution, the performance remained unchanged. Electron dispersive spectroscopy confirmed Ni and Fe electrodeposition. A shift from CH4 to acetate and ethanol production with concentrations reaching 5 and 8 g L−1, respectively, was observed upon increasing the cathode compartment pH to 8.5–9.0. 16S rRNA gene sequencing showed significant changes in the bacterial population at the cathode with Clostridia representing almost two-thirds of the population. Methanosaeta, Methanobrevibacter, and Methanobacterium species dominated the archaeal community.

Description: Rivers are viewed as major pathways of microplastic transport from terrestrial areas to marine ecosystems. However, there is paucity of knowledge on the dispersal pattern and transport of microplastics in river sediments. In this study, a three dimensional hydrodynamic and particle transport modelling framework was created to investigate the dispersal and transport processes of microplastic particles commonly present in the environment, namely, polyethylene (PE), polypropylene (PP), polyamide (PA), and polyethylene terephthalate (PET) in river sediments. The study outcomes confirmed that sedimental microplastics with lower density would have higher mobility. PE and PP are likely to be transported for a relatively longer distance, while PA and PET would likely accumulate close to source points. High water flow would transport more microplastics from source points, and high flow velocity in bottom water layer are suggested to facilitate the transport of sedimental microplastics. Considering the limited dispersal and transport, the study outcomes indicated that river sediments would act as a sink for microplastic pollutants instead of being a transport pathway. The patchiness associated with the hotspots of different plastic types is expected to provide valuable information for microplastic source tracking.

Description: Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe0 oxidation through indirect mechanisms and their impact appears to be limited compared to anaerobic microbes. Several anaerobic mechanisms are known to accelerate Fe0 oxidation. Microbes can consume H2 abiotically generated from the oxidation of Fe0. Microbial H2 removal makes continued Fe0 oxidation more thermodynamically favorable. Extracellular hydrogenases further accelerate Fe0 oxidation. Organic electron shuttles such as flavins, phenazines, and possibly humic substances may replace H2 as the electron carrier between Fe0 and cells. Direct Fe0-to-microbe electron transfer is also possible. Which of these anaerobic mechanisms predominates in model pure culture isolates is typically poorly documented because of a lack of functional genetic studies. Microbial mechanisms for Fe0 oxidation may also apply to some other metals. An ultimate goal of microbial metal corrosion research is to develop molecular tools to diagnose the occurrence, mechanisms, and rates of metal corrosion to guide the implementation of the most effective mitigation strategies. A systems biology approach that includes innovative isolation and characterization methods, as well as functional genomic investigations, will be required in order to identify the diagnostic features to be gleaned from meta-omic analysis of corroding materials. A better understanding of microbial metal corrosion mechanisms is expected to lead to new corrosion mitigation strategies. The understanding of the corrosion microbiome is clearly in its infancy, but interdisciplinary electrochemical, microbiological, and molecular tools are available to make rapid progress in this field.

Description: Since 2010, the Soil Moisture and Ocean Salinity (SMOS) satellite mission monitors the earth emission at L-Band. It provides the longest time series of Sea Surface Salinity (SSS) from space over the global ocean. However, the SSS retrieval at high latitudes is a challenge because of the low sensitivity L-Band radiometric measurements to SSS in cold waters and to the contamination of SMOS measurements by the vicinity of continents, of sea ice and of Radio Frequency Interferences. In this paper, we assess the quality of weekly SSS fields derived from swath-ordered instantaneous SMOS SSS (so called Level 2) distributed by the European Space Agency. These products are filtered according to new criteria. We use the pseudo-dielectric constant retrieved from SMOS brightness temperatures to filter SSS pixels polluted by sea ice. We identify that the dielectric constant model and the sea surface temperature auxiliary parameter used as prior information in the SMOS SSS retrieval induce significant systematic errors at low temperatures. We propose a novel empirical correction to mitigate those sources of errors at high latitudes. Comparisons with in-situ measurements ranging from 1 to 11 m depths spotlight huge vertical stratification in fresh regions. This emphasizes the need to consider in-situ salinity as close as possible to the sea surface when validating L-band radiometric SSS which are representative of the first top centimeter. SSS Standard deviation of differences (STDD) between weekly SMOS SSS and in-situ near surface salinity significantly decrease after applying the SSS correction, from 1.46 pss to 1.28 pss. The correlation between new SMOS SSS and in-situ near surface salinity reaches 0.94. SMOS estimates better capture SSS variability in the Arctic Ocean in comparison to TOPAZ reanalysis (STDD between TOPAZ and in-situ SSS = 1.86 pss), particularly in river plumes with very large SSS spatial gradients.

Description: Highlights: • Transcriptional response to hypoxia-reoxygenation was studied in an OMZ bivalve. • Anaerobic glycolysis and protein quality control pathways were transcriptionally upregulated in hypoxia. • Hypoxia elevated mRNA levels of UCP2 but had no effect on thiol-dependent antioxidants. • No impact of hypoxia-reoxygenation was found on aerobic marker enzymes. • Responses of an OMZ bivalve show parallels to other hypoxia-tolerant bivalves. Abstract: Benthic animals inhabiting the edges of marine oxygen minimum zones (OMZ) are exposed to unpredictable large fluctuations of oxygen levels. Sessile organisms including bivalves must depend on physiological adaptations to withstand these conditions. However, as habitats are rather inaccessible, physiological adaptations of the OMZ margin inhabitants to oxygen fluctuations are not well understood. We therefore investigated the transcriptional responses of selected key genes involved in energy metabolism and stress protection in a dominant benthic species of the northern edge of the Namibian OMZ, the nuculanid clam Lembulus bicuspidatus,. We exposed clams to normoxia (~5.8 ml O2 l−1), severe hypoxia (36 h at ~0.01 ml O2 l−1) and post-hypoxic recovery (24 h of normoxia following 36 h of severe hypoxia). Using newly identified gene sequences, we determined the transcriptional responses to hypoxia and reoxygenation of the mitochondrial aerobic energy metabolism (pyruvate dehydrogenase E1 complex, cytochrome c oxidase, citrate synthase, and adenine nucleotide translocator), anaerobic glycolysis (hexokinase (HK), phosphoenolpyruvate carboxykinase (PEPCK), phosphofructokinase, and aldolase), mitochondrial antioxidants (glutaredoxin, peroxiredoxin, and uncoupling protein UCP2) and stress protection mechanisms (a molecular chaperone HSP70 and a mitochondrial quality control protein MIEAP) in the gills and the labial palps of L. bicuspidatus. Exposure to severe hypoxia transcriptionally stimulated anaerobic glycolysis (including HK and PEPCK), antioxidant protection (UCP2), and quality control mechanisms (HSP70 and MIEAP) in the gills of L. bicuspidatus. Unlike UCP2, mRNA levels of the thiol-dependent mitochondrial antioxidants were not affected by hypoxia-reoxygenation stress. Transcript levels of marker genes for aerobic energy metabolism were not responsive to oxygen fluctuations in L. bicuspidatus. Our findings highlight the probable importance of anaerobic succinate production (via PEPCK) and mitochondrial and proteome quality control mechanisms in responses to oxygen fluctuations of the OMZ bivalve L. bicuspidatus. The reaction of L. bicuspidatus to oxygen fluctuations implies parallels to that of other hypoxia-tolerant bivalves, such as intertidal species.

Description: It is a good method to utilize the grain size distribution curves and cumulative frequency curves of marine or river sediments to estimate the hydrodynamic conditions, transportation processes and sedimentary environment. However, researchers can only rely on Excel or Grapher to plot the curves one by one at the present day. The manual plotting procedures are complicated, and calculating the truncation points is time-consuming. To solve the aforementioned problems, we have developed a software tool to plot cumulative frequency curves and calculate the values of truncation points automatically. The software has the ability to plot curves of hundreds of samples accurately and rapidly, promoting researchers to analyze transport mechanisms and hydrodynamic environments. And it is convenient to apply the software to compare the processes of transportation and deposition between different samples.