Sensor systems for a changing ocean

The papers in this special section focus on sensor system deployment in the field of oceanography. Oceans regulate the Earth's climate and are integral to all known sources of life. Ocean processes are of biological, geological, chemical, or physical nature, occurring at micro- to kilometer scales, from less than seconds to centuries, turning the understanding and the sustainable management of the ocean into a multiscale and multidisciplinary effort. Collection of in situ observation of a volume that covers over 70% of the planet is also inherently challenging and remains generally difficult and costly in time and resources, with so far a rather unsatisfactory result, in particular with respect to space-time resolution. Over the past decade, there has been a steady crescendo of interest to support the development of a truly integrated and sustainably funded Ocean Observing System. This will be achieved with more long-term measurements of key parameters but is impaired by the costs and lack of reliability of ocean sensors in general.Postprint (author's final draft

Environmental conditions of a salt-marsh biodiversity experiment on the island of Spiekeroog (Germany)

Field experiments investigating biodiversity and ecosystem functioning require the observation of abiotic parameters, especially when carried out in the intertidal zone. An experiment for biodiversity–ecosystem functioning was set up in the intertidal zone of the back-barrier salt marsh of Spiekeroog Island in the German Bight. Here, we report the accompanying instrumentation, maintenance, data acquisition, data handling and data quality control as well as monitoring results observed over a continuous period from September 2014 to April 2017. Time series of abiotic conditions were measured at several sites in the vicinity of newly built experimental salt-marsh islands on the tidal flat. Meteorological measurements were conducted from a weather station (WS, https://doi.org/10.1594/PANGAEA.870988), oceanographic conditions were sampled through a bottom-mounted recording current meter (RCM, https://doi.org/10.1594/PANGAEA.877265) and a bottom-mounted tide and wave recorder (TWR, https://doi.org/10.1594/PANGAEA.877258). Tide data are essential in calculating flooding duration and flooding frequency with respect to different salt-marsh elevation zones. Data loggers (DL) for measuring the water level (DL-W, https://doi.org/10.1594/PANGAEA.877267), temperature (DL-T, https://doi.org/10.1594/PANGAEA.877257), light intensity (DL-L, https://doi.org/10.1594/PANGAEA.877256) and conductivity (DL-C, https://doi.org/10.1594/PANGAEA.877266) were deployed at different elevational zones on the experimental islands and the investigated salt-marsh plots. A data availability of 80% for 17 out of 23 sensors was achieved. Results showed the influence of seasonal and tidal dynamics on the experimental islands. Nearby salt-marsh plots exhibited some differences, e.g., in temperature dynamics. Thus, a consistent, multi-parameter, long-term dataset is available as a basis for further biodiversity and ecosystem functioning studies

Modeling of wave-induced irradiance variability in the upper ocean mixed layer

A Monte Carlo based radiative transfer model has been developed for calculating the availability of solar radiation within the top 100 m of the ocean. The model is optimized for simulations of spatial high resolution downwelling irradiance Ed fluctuations that arise from the lensing effect of waves at the water surface. In a first step the accuracy of simulation results have been verified by measurements of the oceanic underwater light field and through intercomparison with an established radiative transfer model. Secondly the potential depth-impact of nonlinear shaped single waves, from capillary to swell waves, is assessed by considering the most favorable conditions for light focusing, i.e. monochromatic light at 490 nm, very clear oceanic water with a low chlorophyll a content of 0.1 mg m−3 and high sun elevation. Finally light fields below irregular wave profiles accounting for realistic sea states were simulated. Our simulations suggest that under open ocean conditions light flashes with 50 % irradiance enhancements can appear down to 35 m depth, and light variability in the range of ±10 % compared to the mean Ed is still possible in 100 m depth

Systems biology analysis of drivers underlying hallmarks of cancer cell metabolism.

Malignant transformation is often accompanied by significant metabolic changes. To identify drivers underlying these changes, we calculated metabolic flux states for the NCI60 cell line collection and correlated the variance between metabolic states of these lines with their other properties. The analysis revealed a remarkably consistent structure underlying high flux metabolism. The three primary uptake pathways, glucose, glutamine and serine, are each characterized by three features: (1) metabolite uptake sufficient for the stoichiometric requirement to sustain observed growth, (2) overflow metabolism, which scales with excess nutrient uptake over the basal growth requirement, and (3) redox production, which also scales with nutrient uptake but greatly exceeds the requirement for growth. We discovered that resistance to chemotherapeutic drugs in these lines broadly correlates with the amount of glucose uptake. These results support an interpretation of the Warburg effect and glutamine addiction as features of a growth state that provides resistance to metabolic stress through excess redox and energy production. Furthermore, overflow metabolism observed may indicate that mitochondrial catabolic capacity is a key constraint setting an upper limit on the rate of cofactor production possible. These results provide a greater context within which the metabolic alterations in cancer can be understood

Investigation and evaluation of the aging behaviour of technical materials as a selection criterion for use in zinc-air flow batteries

Zinc-air secondary batteries have the potential to act as electrochemical energy storage devices in broad industrial applications. The main arguments for developing marketable systems are the good commercial availability and environmental compatibility of zinc [1]. A consortium of different companies and scientific institutions is engaged in the development of a scalable zinc-air secondary battery. For the establishment of the system, the concept and all components, such as the gas diffusion electrode as well as the zinc electrode, are being investigated and optimised. In order to achieve a certain marketability of the battery after the end of the project, the plastic-based housing, sealing and current-conducting components are also being examined for their long-term stability and suitability. The system concept has high demands on the chemical resistance of the components due to the alkaline electrolyte in use. The plastics in question are typical housing materials with good chemical resistance, soft sealing materials based on thermoplastic elastomers and compounds highly filled with graphite for current conduction within the battery. To evaluate the materials, comparative studies are carried out with regard to the material properties, such as mechanical stability and electrical conductivity, and the combustion behaviour to assess the aging between newly produced and aged parts. In particular, the compounds highly filled with graphite presumably exhibit side reactions in contact with the active materials used in the system due to unavoidable impurities. This behaviour is also integrated in the evaluation of the raw material selection

Automated characterization and quantification of hydrocarbon seeps based on frontal illuminated video observations

Hydrocarbon releases, either natural or due to anthropogenic activities, are of major relevance for the marine environment. In this work we specify our approach to quantify these seeps by subsea imaging utilizing camera systems and frontal illumination setups on board remotely operated vehicles. This work showcases, based on a campaign in the region west of Svalbard, improved methodological guidelines for the seep quantification operation together with a novel automated post-mission evaluation. The comparison of automated quantification with manual information extraction illustrates the efficiency of this new method while processing comparable estimates of seep characteristics