ALBERT

Description: Eco-friendly, cost efficient and effective extraction methods have become significant for the industries applying zero waste principles. The two main objectives of this study were; to examine fucoxanthin extraction from wet Phaeodactylum tricornutum using subcritical fluid extraction and to characterize the residual biomass in order to determine the potential application areas. The highest fucoxanthin yield of 0.69 ± 0.05 mg/g wet cell weight was achieved using methanol with solvent-to-solid ratio of 200:1 at 120 rpm, 20 MPa pressure and at 35 °C for 60 min by subcritical extraction. Microscopy images showed that most of the cells were disrupted and intracellular components were effectively released. Based on the results of energy dispersive spectroscopy, biomass contained a mixture of organic molecules including mainly carbon (57–72%), oxygen (26–41%), magnesium (0.6–1.4%) and silica (0.4–1%) (wt%). These results make the residual biomass a potential candidate for various areas such as bioenergy, material sciences and sensor technologies.

Description: Subsurface-intensified anticyclones are ubiquitous in the ocean, yet their impact on the large-scale transport of heat, salt and chemical tracers is poorly understood. These submesoscale coherent vortices (SCVs) can trap and advect waters thousands of kilometers away from the formation region, providing a transport pathway that is unresolved by low-resolution Earth System Models. However, knowledge of the importance of these eddies for the large scale circulation is hindered by the lack of systematic observations. Here, we take advantage of the global network of Argo floats to identify occurrences of these eddies, which appear as weakly stratified anomalous water masses with Gaussian-shaped vertical structures. We develop a general algorithm to detect subsurface eddies that have propagated away from their source region, and apply it to the database of Argo float profiles, resulting in roughly 4000 detections from more than 20 years of observations. We further group detections into regional populations to identify hot-spots of generation and mechanisms of formation. Analysis of regional SCV statistics reveals important sites of SCV generation in Eastern Boundary Upwelling Systems, marginal sea overflows, and mode water formation regions along major open-ocean fronts. Because of the heat and salt anomaly contained within their cores, SCV could leave a significant imprint on the hydrographic properties of water masses in regions of high SCV density.

Description: The vast majority of active volcanism that is located at plate boundaries can be easily explained by plate tectonic processes. Intraplate volcanism, which incorporates some of the smallest and largest volcanic events on Earth, cannot be successfully explained by a single process or model. The most volumetrically significant intraplate volcanic events are associated with the arrival of the head of a thermo-chemical anomaly rising from the deep mantle and impacting the base of the lithosphere. This event generates massive and short-lived magmatic activity over a wide area (up to 2000 km across), forming a large igneous province. A long-lived hotspot track can form over the mantle plume tail and is best illustrated by the formation of age progressive volcanic chains, such as the famous Hawaiian-Emperor chain. Millions of smaller solitary volcanic edifices, non-age progressive volcanic chains and provinces, on the other hand, have other potential mechanisms of origin. Potential models comprise decompression melting due to lithospheric extension, destabilization of fusible lithologies in the lithospheric mantle, small scale sub-lithospheric convection, or lithospheric delamination.

Description: The concept of biosorption results from the “passive” (nonmetabolic) interaction of a chemical species with a particle of a biological material. This interaction can be practically exploited, for example, for removal of toxic substances of wastewaters or for the enrichment of a fertilizer with micronutrients. In this work, equilibrium and dynamic data obtained with “low-cost” biomaterials of algal waste or invasive seaweed species have been reviewed and critically analyzed in the context of a circular economy. The concept of a biosorption unit, oriented to the valorization of any solid residual material of algal biomass, can be considered as a real possibility in a biorefinery process; but to accomplish this goal it is necessary that the emphasis on research must definitely move from laboratory scale toward pilot plant assays.

Description: Gas hydrates dissociation could induce or trigger submarine landslides, especially in upper continental slopes where hydrates are vulnerable to natural and artificial perturbations. This work investigates destabilization mechanisms of an upper continental slope undergoing hydrate dissociation and identifies spatiotemporal failure modes influenced by characteristics of the overburden above the hydrate-bearing layer (i.e. the hydrate reservoir). A Thermo-Hydro-Chemical coupled numerical model of transient pore pressure induced by hydrate dissociation is coupled with the limit equilibrium slope analysis method to study the spatiotemporal evolution of the potential sliding plane and to calculate the corresponding factor of safety. The results suggest that overpressure generated by the liberated fluid from hydrate dissociation is the primary reason for instability in a gentle marine slope. The study identifies three sliding modes, namely co-melting non-interface sliding, co-melting interface sliding, and post-melting non-interface sliding, depending on the overburden's characteristics, including overburden thickness, permeability, and cohesion. Co-melting non-interface sliding takes place during hydrate dissociation if the hydrate reservoir underlies a thin, pervious and low-cohesion overburden cover. For less permeable and more cohesive overburdens, the potential sliding plane is deeper and co-melting interface sliding could be triggered due to overpressure developed at the reservoir-overburden interface. If the hydrate reservoir is covered by a thick, low-permeability and slightly cohesive overburden, post-melting non-interface sliding could occur after the hydrates are completely dissociated. This failure is delayed, because the gas/water trapped at the interface during hydrate dissociation is insufficient to trigger instability due to very high overburden stresses. However, as the gas migrates upwards over time and encounters a weak zone in the overburden deposits, failure could happen within the overburden deposits even after hydrate dissociation stops. The findings help to improve our fundamental understanding about the destabilization mechanism and failure modes of the continental slopes undergoing hydrate dissociation, and to delineate the vulnerable configurations of the slopes.

Description: n our daily lives, we consume foods that have been transported, stored, prepared, cooked, or otherwise processed by ourselves or others. Food storage and preparation have drastic effects on the chemical composition of foods. Untargeted mass spectrometry analysis of food samples has the potential to increase our chemical understanding of these processes by detecting a broad spectrum of chemicals. We performed a time-based analysis of the chemical changes in foods during common preparations, such as fermentation, brewing, and ripening, using untargeted mass spectrometry and molecular networking. The data analysis workflow presented implements an approach to study changes in food chemistry that can reveal global alterations in chemical profiles, identify changes in abundance, as well as identify specific chemicals and their transformation products. The data generated in this study are publicly available, enabling the replication and re-analysis of these data in isolation, and serve as a baseline dataset for future investigations.

Description: A comparison of gouge and hammer coring techniques in intertidal wetland soils highlights a significant effect of soil compaction of up to 28% associated with the widely applied hammer coring method employed in Blue Carbon research. Hammer coring reduces the thickness of the soil profile and increases the dry bulk density, which results in an overestimation of the soil OC stock of up to 22%. In saltmarshes with multiple different soil units, we show that hammer coring is unsuitable for the calculation of OC stocks and should be avoided in favour of Russian or gouge cores. Compaction changes both soil dry bulk density and porosity and we show that resultant radiometric chronologies are compromised, almost doubling mass accumulation rates. While we show that the OC (%) content of these sediments is largely unchanged by coring method, the implication for OC burial rates are profound because of the significant effect of hammer coring on the calculation of soil mass accumlation rates.

Description: Seagrasses provide multiple ‘ecosystem services' in coastal waters, including carbon sequestration. However, this ‘Blue Carbon’ potential has been only evaluated for certain species from some areas of the world. In this study, we provide initial estimates on the magnitude and local variability of carbon sequestration, as organic carbon stocks, for seagrass meadows of Cymodocea nodosa (Ucria) Ascherson in the oceanic island of Gran Canaria (Canary Islands, Spain, central-eastern Atlantic). Six seagrass meadows were selected; at each meadow, cores inserted up to 30 cm in the seabed were collected in the ‘interior’, ‘edge’ and ‘unvegetated’ bottoms immediately adjacent to seagrass patches. We estimated organic carbon (Corg) pools by means of the Loss of Ignition (LOI) procedure. Overall, larger Corg pools were observed in the ‘interior’ and 'edges' of meadow patches than in adjacent ‘unvegetated’ bottoms. At the meadow-level, Corg pools were not predicted neither by the meadow area, nor by the mean shoot density, or sediment grain fractions. Overall, the total estimated stock was 86.20 ± 19.06 Mg C ha−1. By considering the total potential extension of seagrass meadows across the entire island perimeter, we estimated a total stock of 60.34 Gg of C, for a mean estimated financial value of 919,432.249 € (1313.47 € ha−1), which ranges between 351,631.35 € (502.33 € ha−1) and 1,498,954.45 € (2141.36 € ha−1), according to varying market prices in the last 5 years. This work highlights, therefore, the importance of meadows underpinned by C. nodosa not only at an ecological, but also at an economic level, in particular from the perspective of regional climate change adaptation strategies.

Description: Ciona intestinalis is within the group of taxa that are spreading globally and is one of the most thriving invasive marine species, known to depress both species richness and abundance at a local scale in distinct geographic areas. It is a dominant biofouling agent, associated with the decreasing economic incomes from aquaculture operations around the world. Ciona intestinalis was first observed in 2007 at Straumsvík in Southwest Iceland. The present study was designed to provide general information on its current distribution across Icelandic harbours. The species was found only on the SW coast of Iceland, in dense aggregations reaching up to 876 ind/m2 in all harbours from Grindavík to Akranes. The current work provides information that can be used to track the dispersal of C. intestinalis populations along the Icelandic coast and for the development of effective management decisions.