Characterization of the submarine disposal of a Bayer effluent (Gardanne alumina plant, southern France): V: Evolution of metal and metalloid concentrations in the seawater column of the discharge area (Mediterranean Sea) from 2016 to 2024.

Mass spectrometry imaging (MSI) is widely used in biomedical sciences, as well as in plant sciences or microbiological studies. However, it is much less prominent in the earth sciences, despite holding enormous potential. For example, marine and lake sediments are excellent archives of the past, as they store the remnants of organisms from the water column and from surrounding land. These organisms leave behind fossil molecules that can be employed to reconstruct the environmental conditions during their lifetime, and hence to study the climate evolution of Earth. Focusing on matrix-assisted laser desorption/ionization (MALDI) imaging, we herein show that it is possible to read these molecular signatures in micrometer-sized spots, and thus to characterize climate variability with unprecedented resolution. However, obtaining this information is not trivial, and challenges arise from the nature of geological samples, low analyte concentrations, strong matrix effects, and from the need to reference the micrometer-scale maps to the original, large samples. Here we present a detailed tutorial on (i) how to select and prepare suitable samples, (ii) how to analyze them while avoiding the most common pitfalls and (iii) how to process the resulting large and complex dataset. We hope that this tutorial might contribute to inspire the use of MALDI in paleoenvironmental reconstructions in particular and in the earth sciences in general, and at the same time be useful to imaging applications across research fields.

Numerical modeling of dissolved mercury dynamics and transformation in sea water in Minamata Bay, Japan.

Rapid methylmercury demethylation in phytoplankton during algal blooms: insights from mercury isotopes and dynamic modeling.

Floating macrophyte growth and decomposition greatly affects the exogenous antimony mobility and microbial community functions in water-sediment system.

Spatial distribution, abundance, and characterization of emerging plastic forms in binational coastal ecosystems.

Microplastic accumulation and vertical distribution in the Delaware Estuary estuarine turbidity maximum.

• PIV velocity measurements in a high Reynolds number turbulent shear flow, conducted in a flume tank. • Implementation of a new POD-based method for wave-turbulence separation. • Characterization of the turbulent flow gaussianity as a function of the wave propagation direction. • Increase of the TKE across the water column due to waves, especially when propagating against the current. • Quadrant analysis of the flow structures distortion under the wave action. To accurately characterize prospective tidal energy sites where vortices and wavy environment coexist, it is essential to gain a deeper understanding of wave-vortex interactions. Given the complexity and multi-scale nature of these coupling processes, we focus on the interaction between regular surface waves and vortices developing in the water column. Based on Particle Image Velocimetry measurements conducted in a flume tank, two flow configurations are studied: monochromatic waves propagating either with or against the current, each interacting with large-scale flow structures in a high Reynolds number turbulent shear flow. These flow configurations are characterised by a negative mean velocity vertical gradient. In this work, the Proper Orthogonal Decomposition is implemented to extract the wave velocity field from raw velocity measurements. After validating this wave-turbulence decomposition, the results show that the wave propagation modifies the integral time scale of the free flow, the vertical mixing and its associated energy transfer. The energetic vertical exchanges are primarily governed by the free surface proximity, the kinetic energy levels in the free flow without waves and the wave propagation direction. Waves lead to limit the vertical mixing by reducing the production of the kinetic energy. A quadrant analysis also reveals the instantaneous flow distortion under the wave action, especially when waves propagate against the current.

Self-starting characteristics and dynamic response of a free-spinning cross-flow air turbine for oscillating water columns under irregular wave conditions

Focusing wave energy on an oscillatory wave column (OWC) is an effective way to enhance its energy harvesting efficiency, which is quantified by the capture width ratio (CWR). A properly designed rectangular OWC can achieve a maximum CWR greater than 100% because of its inherent ability of wave focusing. For an infinite row of OWC devices under perpendicularly incident waves, the hydrodynamic efficiency of each OWC device is affected by two factors: wave focusing and possible transverse sloshing. Due to symmetry, this configuration is equivalent to one OWC device within a wave flume. This study uses numerical simulations to investigate the impact of wave focusing and transverse sloshing on the performance of an OWC device in a wave flume. The peak CWR is found to decrease with a decrease in the flume width. It reduces from 1.402 to 0.946 as the flume-width-to-OWC-width ratio decreases from 5 to 1.05. Through wave ray visualization, this paper found that the fundamental mechanism of transverse sloshing that causes minimum values of CWR is the multiple reflection of the waves between the flume side wall and the centre line of the OWC. • Mechanisms of wave focusing in front of a rectangular OWC device is discovered. • OWC Efficiency of a rectangular OWC reduces with the reduction of the flume width. • Mechanism of transverse sloshing is multiple reflection in the trans-flume direction.

Epidermal mucus is a complicated mixture of macromolecules which acts as the first line of defence for organisms against abrasions and infections. We quantified the carbohydrate (monosaccharide) composition of the mucus from four Elasmobranchii hosts, including eagle rays (Myliobatis tenuicaudatus), Port Jackson sharks (Heterodontus portusjacksoni), Australian angelsharks (Squatina australis) and whitespotted skates (Dentiraja cerva). Elasmobranchii had low amounts of mucus and a low proportion of carbohydrates (< 10%) compared with other marine organisms. Four key monosaccharides: glucose, glucosamine, galactose and fucose, were identified in mucus samples. Hosts exhibited distinct, species-specific monosaccharide signatures. We identified key carbohydrate microbial genes from host and water microbiomes. Elasmobranch microbiomes had a higher relative abundance of carbon utilisation genes compared to the water column and contained gene pathways for the utilisation of specific monosaccharides found in host mucus, suggesting that the host mucus was a regulator of the microbiome. Elasmobranch epidermal microbiomes have the genetic machinery required for detecting, transporting and metabolising monosaccharides and other carbohydrates present in the host mucus, demonstrating the selective nature of Elasmobranch epidermal mucus.

Hydrodynamic performance of oscillating water column wave energy converter arrays of offshore hybrid aquaculture–energy platforms

The roles of sea cucumber Apostichopus japonicas mediating functional microbial communities to promote sediment N cycling.

ARTICLE HIGLIGHTS- Langat River water and sediment quality deteriorate toward downstream.- Dissolved organic phosphorus increases near agricultural areas.- Sediment phosphate retention dominated by non-labile organic phosphorus.- Downstream pollution linked to sediment sorption and nearby agriculture.ABSTRACTThe Langat River traverses rapidly developing urban areas in Malaysia and is significantly affected by anthropogenic activities. The introduction of excessive phosphorus into rivers poses a significant ecological issue. Water and sediments were sampled from nine stations at Langat River to evaluate the current and potential impacts of organic phosphorus. The water quality parameters indicate a progressive decline downstream, attributed to allochthonous sources from tributaries and land use practices, particularly agriculture. Inorganic substances are the principal cause of pollution in the river while degradation of organic pollution biologically is reduced. Dissolved organic phosphorus (DOP) plays a significant role at stations that are either relatively unpolluted or adjacent to agricultural areas, serving as a potential source of bioavailable phosphorus. The total organic phosphorus in the sediment increased downstream, predominantly comprising non-labile fractions (67–78%). The labile fractions exhibit strong correlations with dissolved oxygen (DO) (r = -0.797), dissolved organic phosphorus (DOP) (r = 0.931), and conductivity (r = 0.837), suggesting internal loading to the water column. Increased non-labile fractions indicate the sediment's capacity to retain organic phosphorus. The downstream stations exhibit elevated risk owing to high sorption capacity and proximity to agricultural sources of organic phosphorus.

Wave energy converters (WECs) such as Oscillating Water Column (OWC) devices hold great promise for renewable energy generation, but their long-term reliability under harsh marine conditions remains a critical challenge. This paper addresses the risk assessment gap for OWC systems by introducing a novel integrated framework that bridges technical reliability with economic viability. The proposed Hexagon Risk Assessment methodology extends traditional Failure Modes and Effects Analysis (FMEA) by incorporating six evaluation criteria (including exposure, detectability, control measures, and economic impact) rather than the standard three. These criteria are weighted and aggregated using a Pythagorean fuzzy multi-criteria decision-making (MCDM) approach, providing a robust prioritisation of failure modes. Compared to previous FMEA-based or single-method studies, the Hexagon methodology offers a more comprehensive evaluation of OWC risks, capturing complex environmental and operational uncertainties. Applied to a representative case study reflecting real-world operational constraints, the methodology successfully identified the most critical failure modes, with aging degradation, resonance tuning failure, and extreme weather events emerging as top risks. Among the evaluated criteria, severity, exposure, and economic impact were found to have the greatest influence on overall risk prioritisation. The results confirm that this holistic risk assessment approach can enhance maintenance planning and design optimisation for wave energy systems, ultimately supporting cost-reduction strategies necessary for commercial deployment.

Abstract. Coccolith dissolution in the water column is an important process in the marine carbon cycle. Identifying dissolution in water column samples has been difficult due to a lack of experimental reference datasets showing dissolution morphologies. We conducted a laboratory CaCO3 dissolution experiment to detect differential dissolution morphologies of three selected coccolithophore (abundant marine calcareous phytoplankton) species, Coccolithus braarudii, Helicosphaera carteri, and Scyphosphaera apsteinii. These species were selected because they are ecologically and biogeochemically important (significant contributors to CaCO3 production) and have been less studied than Gephyrocapsa. Muroliths of S. apsteinii dissolve faster than lopadoliths, which in turn dissolve as fast as H. carteri but faster than C. braarudii. In S. apsteinii lopadoliths, dissolution rate depends on the crystallographic orientation of the crystals. Comparison with field samples shows that experimental data are helpful when interpreting field samples. For example, we identify dissolution in water and sediment samples reported in the literature. In C. braarudii dissolution reveals a nanostructure on the proximal side of the distal shield, an observation that has implications for coccolith biomineralization models, which do not currently account for the formation of such a structure. This nanostructure features “units” of ca. 50–100 nm and resembles the nanostructure well known from extracellular calcifiers such as molluscs and foraminifera. Whether this resemblance is underpinned by a similar formation mechanism remains unknown, but we think this unlikely.

Coccolithophores are important components of marine phytoplankton and are found to be useful indicators of the environmental conditions of the upper water column. In this study, we investigate coccolithophore abundance and composition in the Cretan Sea and South Cretan area (Eastern Mediterranean), and their relation to prevailing hydrodynamic conditions during late February/early March 2019. Results showed that total coccolithophore abundance ranged from 26.3 × 102 to 258.8 × 102 coccospheres L−1, averaging at 135.8 × 102 coccospheres L−1. Among the 45 identified species, the opportunistic Emiliania huxleyi was the most dominant, representing 89% of the coccolithophore assemblage. In the Cretan Sea, this species showed relatively homogeneous abundances throughout the upper 100 m depth of the water column; however, towards the Rhodes Cyclone, where a weak stratification had started, and the mixed layer was relatively shallow, higher abundances were found at depths shallower than 50 m. Syracosphaera molischii co-occurred with Emiliania huxleyi, whereas Rhabdosphaera clavigera, Syracosphaera pulchra, and Syracosphaera mediterranea were also present but in lower abundances, reflecting the influence of warm, salty Levantine Surface Water. Based on the morphological analysis, Emiliania huxleyi was mostly represented by heavily calcified forms consistent with winter-spring patterns in the Aegean Sea. The observation of signs of dissolution with high relative abundances of etched/corroded coccospheres indicates the sensitivity of Emiliania huxleyi to the prevailing circulation pattern during the 2019 mixing event within the Rhodes gyre.

Extreme acidic environments represent natural laboratories for investigating the mechanisms of microbial community assembly, yet the ecological processes structuring these communities remain incompletely understood. Here, we investigate how spatial partitioning, hydrodynamics, and colonization history shape microbial succession in a unique sulfur-rich, acidic river of volcanic origin in northern Patagonia. We combined 16S rRNA gene profiling and shotgun metagenomics with a multi-scale experimental framework encompassing water column fractionation and colonization assays under native and controlled conditions. Microbial diversity was strongly influenced by spatial fractionation, with free-living communities exhibiting higher richness and temporal variability than particle-associated assemblages. Water flow modulated community structure, increasing evenness in free-living fractions under high-flow conditions, but had limited impact on particle-attached communities. Colonization of sulfur-beads followed a structured successional trajectory, with autotrophic sulfur oxidizers dominating early stages and heterotrophs adapted to biofilm lifestyles increasing over time. Ex situ recolonization assays revealed strong priority effects, with initial colonizers determining successional trajectories. Turnover analyses revealed that the balance among stochastic and deterministic assembly processes shifted across communities with pronounced stochasticity in the water column and flow-dependent effects in free-living communities, while biofilm associated communities on sulfur-beads exhibited stronger contribution of deterministic selection. These ecological patterns were mirrored by functional differentiation, with gene enrichment analyses revealing adaptive signatures of substrate attachment and resource acquisition. By integrating fine-scale environmental variation with colonization dynamics, this study reveals how microscale habitat structure and temporal fluxes jointly modulate microbial community assembly rules, offering a nuanced framework to dissect ecological processes in extreme systems.

Evidence for the shallow cycling of calcium carbonate in the global ocean is mounting, but the mechanisms driving the dissolution of thermodynamically stable polymorphs, like aragonite and calcite, in the surface ocean remain unconstrained. Here, we quantify how microbial metabolism creates acidic microenvironments in marine particles that enhance the local dissolution of calcite despite supersaturated conditions in bulk waters. A temporal decoupling of particle deoxygenation and acidification suggests that respiration-derived carbon dioxide is not the sole driver of the observed undersaturation. Rapid dissolution occurs in particles exhibiting bacterial growth, with rates exceeding abiotic dissolution at the same bulk saturation by more than an order of magnitude. We observe the highest particle-associated dissolution rates at intermediate settling velocities, indicating that a trade-off between elevated mass transfer due to settling and bacterial respiration governs the ensuing dissolution rates. Translation of our experiments to the water column suggests that microbially driven undersaturation in marine particles may dissolve sufficient calcite in the mesopelagic ocean to extend particle transit times by eliminating this vital ballast mineral, reducing the efficiency of organic carbon sequestration.

Abstract Water turbidity is an important indicator of water quality, as it allows for conclusions on the particles contained in the water. Suspended matter, sediments, algae and other particles in the water column influence the light transmission, oxygen content, nutrient supply and productivity of a water body. Information on water turbidity is therefore relevant for a wide range of limnological and oceanographic questions. In particular, the vertical turbidity stratification plays an important role in understanding the ecological relationships within a water body. Conventional in-situ measurement methods provide only isolated, point-based turbidity profiles, which fail to capture the overall turbidity conditions throughout the entire water body, including all small-scale lateral and vertical variations. Hence, the utilization of Light Detection and Ranging (LiDAR) bathymetry data for assessing area-wide depth-resolved water turbidity information shows great potential. By analysing the waveform of the backscattered LiDAR signal, information about the turbidity of the water can be derived. In this paper we present a signal analysis approach that allows to derive depth resolved turbidity parameter fields from LiDAR bathymetry data. The methodology was tested on a pre-alpine mountain lake using a UAV LiDAR bathymetry system. For validation purposes, a comprehensive set of in-situ water property measurements is available, which were collected at the same day as the bathymetric data. The results show that the turbidity parameters determined from the LiDAR data generally correspond to the trends observed in the conventional water property measurements, although local deviations are present.