Plastic debris has become an environmental problem during recent years. Among the plastic debris, microplastics (<5 mm; MPLs) imply an extra problem due to their capacity to enter into the fauna ...through ingestion. In this work, we study the capacity of three MPLs, that include high-density polyethylene (HDPE), polystyrene (PS) and polystyrene carboxylate (PS-COOH), to sorb 18 perfluoroalkyl substances (PFASs; including carboxylic acids, sulphonates and one sulphonamide) from the surrounding waters (freshwater and seawater).
Conclusions drawn from the results are that perfluoro sulphonates and sulphonamides have more tendency to be sorbed onto MPLs. In addition, PS and PS-COOH have more affinity for PFASs than HDPE. Finally, the increment of conductivity and pH of the water decreases the exposure time that is necessary to reach equilibrium. However, the presence of salts decreases the tendency of PFASs to be sorbed onto plastic surfaces. These results highlight the problem associated with the presence of MPLs in inland and marine waters since toxic compounds can be sorbed onto surrounding plastics that could be ingested by aquatic fauna.
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•The adsorption of PFASs on microplastics has been assessed.•For the same materials, aged microplastics presented higher adsorption capacities.•Microplastics adsorption capacity’ for PFASs was as follows: polystyrene > polystyrene carboxylate > high-density polyethylene.
The mechanisms ruling the adsorption of PFASs onto MPLs are mainly hydrophobic forces, age and size of MPLs, the critical micelle concentration of PFAS and the salting out effect.
Ocean acidification (OA) has the potential to restructure ecosystems due to variation in species sensitivity to the projected changes in ocean carbon chemistry. Ecological models can be forced with ...scenarios of OA to help scientists, managers, and other stakeholders understand how ecosystems might change. We present a novel methodology for developing estimates of species sensitivity to OA that are regionally specific, and applied the method to the California Current ecosystem. To do so, we built a database of all published literature on the sensitivity of temperate species to decreased pH. This database contains 393 papers on 285 species and 89 multi-species groups from temperate waters around the world. Research on urchins and oysters and on adult life stages dominates the literature. Almost a third of the temperate species studied to date occur in the California Current. However, most laboratory experiments use control pH conditions that are too high to represent average current chemistry conditions in the portion of the California Current water column where the majority of the species live. We developed estimates of sensitivity to OA for functional groups in the ecosystem, which can represent single species or taxonomically diverse groups of hundreds of species. We based these estimates on the amount of available evidence derived from published studies on species sensitivity, how well this evidence could inform species sensitivity in the California Current ecosystem, and the agreement of the available evidence for a species/species group. This approach is similar to that taken by the Intergovernmental Panel on Climate Change to characterize certainty when summarizing scientific findings. Most functional groups (26 of 34) responded negatively to OA conditions, but when uncertainty in sensitivity was considered, only 11 groups had relationships that were consistently negative. Thus, incorporating certainty about the sensitivity of species and functional groups to OA is an important part of developing robust scenarios for ecosystem projections.
Viruses modulate microbial communities and alter ecosystem functions. However, due to cultivation bottlenecks, specific virus-host interaction dynamics remain cryptic. In this study, we examined 127 ...single-cell amplified genomes (SAGs) from uncultivated SUP05 bacteria isolated from a model marine oxygen minimum zone (OMZ) to identify 69 viral contigs representing five new genera within dsDNA Caudovirales and ssDNA Microviridae. Infection frequencies suggest that ∼1/3 of SUP05 bacteria is viral-infected, with higher infection frequency where oxygen-deficiency was most severe. Observed Microviridae clonality suggests recovery of bloom-terminating viruses, while systematic co-infection between dsDNA and ssDNA viruses posits previously unrecognized cooperation modes. Analyses of 186 microbial and viral metagenomes revealed that SUP05 viruses persisted for years, but remained endemic to the OMZ. Finally, identification of virus-encoded dissimilatory sulfite reductase suggests SUP05 viruses reprogram their host's energy metabolism. Together, these results demonstrate closely coupled SUP05 virus-host co-evolutionary dynamics with the potential to modulate biogeochemical cycling in climate-critical and expanding OMZs.
The last decade has seen a considerable increase in the use of silver nanoparticles (AgNPs), which are found in many every-day consumer products including textiles, plastics, cosmetics, household ...sprays and paints. The release of those AgNPs into aquatic environments could be causing ecological damage. In this study we assess the toxicity of AgNPs of different sizes to two species of microalgae, from freshwater and marine environment (Chlamydomonas reinhardtii and Phaeodactylum tricornutum respectively). Dissolution processes affect the form and concentration of AgNPs in both environments. Dissolution of Ag from AgNPs was around 25 times higher in marine water. Nevertheless, dissolution of AgNPs in both culture media seems to be related to the small size and higher surface area of NPs. In marine water, the main chemical species were AgCl2− (53.7%) and AgCl3−2 (45.2%). In contrast, for freshwater, the main chemical species were Ag+ (26.7%) and AgCl− (4.3%). The assessment of toxicological responses, specifically growth, cell size, cell complexity, chlorophyll a, reactive oxygen species, cell membrane damage and effective quantum yield of PSII, corroborated the existence of different toxicity mechanisms for microalgae. Indirect effects, notably dissolved Ag ions, seem to control toxicity to freshwater microalgae, whereas direct effects, notably attachment onto the cell surface and the internalization of AgNPs inside cells, seem to determine toxicity to the marine species studied. This research contributes to knowledge on the role of intrinsic and extrinsic factors in determining the behavior of NPs in different aquatic environments and the interaction with microalgae.
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•Ionic strength and size of AgNPs govern the dissolution process.•Toxicity of AgNPs to freshwater microalgae seems to be determined by the presence of Ag+ in culture media (indirect effect).•Toxicity of AgNPs in marine microalgae seems to be ruled by direct effects of AgNPs, as adsorption and internalization.
Climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and pollution in its many forms are fundamentally altering the chemistry of the ocean, often on a global scale and, in some ...cases, at rates greatly exceeding those in the historical and recent geological record. Major observed trends include a shift in the acid-base chemistry of seawater, reduced subsurface oxygen both in near-shore coastal water and in the open ocean, rising coastal nitrogen levels, and widespread increase in mercury and persistent organic pollutants. Most of these perturbations, tied either directly or indirectly to human fossil fuel combustion, fertilizer use, and industrial activity, are projected to grow in coming decades, resulting in increasing negative impacts on ocean biota and marine resources.
•Chitosan-collagen-alginate (CCA) cushion was prepared and attached to an anti-seawater immersion PU membrane to compose CCA composite dressing.•CCA composite dressing prevent wound from seawater ...immersion and promote wound healing.
The present study aimed to prepare a composite dressing composed of collagen, chitosan, and alginate, which may promote wound healing and prevent from seawater immersion. Chitosan-collagen-alginate (CCA) cushion was prepared by paintcoat and freeze-drying, and it was attached to a polyurethane to compose CCA composite dressing. The swelling, porosity, degradation, and mechanical properties of CCA cushion were evaluated. The effects on wound healing and seawater prevention of CCA composite dressing were tested by rat wound model. Preliminary biosecurity was tested by cytotoxicity and hemocompatibility. The results revealed that CCA cushion had good water absorption and mechanical properties. A higher wound healing ratio was observed in CCA composite dressing treated rats than in gauze or chitosan treated ones. On the fifth day, the healing rates of CCA composite dressing, gauze, and chitosan were 48.49%±1.07%, 28.02%±6.4%, and 38.97%±8.53%, respectively. More fibroblast and intact re-epithelialization were observed in histological images of CCA composite dressing treated rats, and the expressions of EGF, bFGF, TGF-β, and CD31 increased significantly. CCA composite dressing showed no significant cytotoxicity, and favorable hemocompatibility. These results suggested that CCA composite dressing could prevent against seawater immersion and promote wound healing while having a good biosecurity.
The global demand for valuable metals and minerals necessitates the exploration of alternative, sustainable approaches to mineral recovery. Seawater mining has emerged as a promising option, offering ...a vast reserve of minerals and an environmentally friendly alternative to land-based mining. Among the various techniques, Nanofiltration (NF) has gained significant attention as a preliminary treatment step in Minimum Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) schemes. This study focused on the potential of two underexplored commercial polyamide based NF membranes, Synder NFX and Vontron VNF1, with enhanced divalent over monovalent separation factors, in optimizing the extraction of magnesium hydroxide (Mg(OH)2) from seawater and seawater reverse osmosis (SWRO) brines. The research encompassed a thorough characterization of the membranes utilizing advanced physic-chemical analytical techniques, followed by rigorous experimental assessments using synthetic seawater and SWRO brine in concentration configuration. The findings highlighted the superior selectivity of NFX for magnesium recovery from SWRO brine and the promising concentration factors of VNF1 for seawater treatment. Cross-validation of experimental data with a mathematical model demonstrated the model's reliability as a process design tool in predicting membrane performance. A comprehensive techno-economic evaluation demonstrates the potential of NFX, operating optimally at 23 bar pressure and 70% permeate recovery rate, to yield an estimated annual revenue of 5.683 M€/yr through Mg(OH)2 production from SWRO brine for a plant with a nominal capacity of 0.8 Mm3/y. This research shed light on the promising role of NF membranes in enhancing mineral recovery taking benefit of their separation factors and emphasizes the economic viability of leveraging NF technology for maximizing magnesium recovery from seawater and SWRO brines.
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•NFX and VNF1 membranes were tested for seawater/brine valorization.•Tests were conducted at 20 bar and permeate recovery p.r (0–80%).•NFX showed higher Mg selectivity than VNF1 in both scenarios.•Mg(OH)2 purity >97% was reached (NFX, SWRO brine, 10 bar and p.r 80%).•The highest achieved revenue was 5.7 M€/yr (NFX, SWRO brine, 23 bar, p.r 70%).
•Studied the bond behaviour between FRP and seawater sea sand concrete using push-out tests.•Both pultruded and filament winding FRP tubes were included in the testing program.•Investigated the ...effect of fibre types (i.e. glass, carbon and basalt fibres) on bond strength.•Investigated the effect of fibre orientation and diameter-to-thickness ratio on bond strength.•The mechanical and chemical bond strength of concrete filled FRP tubes were obtained.
In the present study the bond-slip behavior between FRP tubes and seawater sea sand concrete is studied using push-out tests. Pultruded and filament winding FRP tubes with different fibre orientations and diameter-to-thickness ratios (D/t) were constructed to investigate the effect of confinement pressure on the bond behaviour. Moreover, to study the effect of fibre type, three types of FRP (i.e.; GFRP, CFRP and BFRP) were used. In addition, the mechanical and chemical bond strength of concrete filled FRP tubes were quantified and compared. CFRP and BFRP tubes showed the highest and the lowest bond strengths, respectively. Furthermore, it was concluded that the real confinement pressure of the tubes has a significant effect on the bond strength: the greater the real confinement pressure, the larger the bond strength (i.e. the tubes with smaller D/t ratio and fibres orientated in 89° showed greater bond strength compared to the tubes with larger D/t and different fibres orientations). Repeating the push-out test for four times, for each sample, showed that the slip starts earlier by increasing the number of repetition, while the bond strength remained almost the same. This shows that the bond strength of tubes is mostly governed by the friction (confinement pressure) rather than the adhesion (chemical bond).
Ti finds widespread opportunities in harsh seawater environment because of unique corrosion resistance. However, one tough challenge is the biofouling problem caused by the inherent friendliness to ...the attachment of biological organisms. In this study, a facile electrodeposition approach affords high driving force for crystal growth, and dendritic Ag has been constructed onto Ti substrate. After being modified with dodecanethiol vapor, superhydrophobicity is realized relying on the anchored hydrophobic moieties and the voids in dendritic Ag matrix. Superoleophilicity enables oil phase to drive out air in the matrix for finally achieving slippery liquid-infused porous surface (SLIPS) with high flatness and smoothness. Diatoms and green algae are used as the typical biofouling organisms to assay antifouling behavior of Ti covered by superhydrophobic (SHP Ti) and SLIPS surface (SLIPS Ti). After immersion for 14 days, the number of diatoms and green algae on bare Ti surface respectively reaches 1.60 × 1011 and 1.57 × 1011 cells/cm2. Meanwhile, for Ti covered by SLIPS, the cell density is only 6.84 × 107 cells/cm2 and 5.05 × 107 cells/cm2, decreasing to ca. 4 orders of magnitude smaller than that of bare Ti. For SHP Ti, its biofouling inhibition effect is lower than that of SLIPS Ti. Therefore, building SLIPS onto the surface has afforded a promising way for Ti to inhibit biofouling in seawater environment.
Bio-inspired liquid-infused surface based on dendritic Ag matrix from electrodeposition affords prominent biofouling inhibition to underneath Ti in seawater environment. Display omitted
•Dendritic Ag grows onto Ti via electrodeposition.•Slippery liquid-infused Ag matrix is obtained by three steps.•Liquid-infused surface enables high biofouling inhibition to Ti.
Any assessment of plastic contamination in the marine environment requires knowledge of the polymer type and the additive content of microplastics. Sequential pyrolysis-gas chromatography coupled to ...mass spectrometry (Pyr-GC/MS) was applied to simultaneously identify polymer types of microplastic particles and associated organic plastic additives (OPAs). In addition, a scanning electron microscope equipped with an energy-dispersive X-ray microanalyser was used to identify the inorganic plastic additives (IPAs) contained in these particles. A total of ten particles, which were optically identified as potentially being plastics, were extracted from two sediment samples collected from Norderney, a North Sea island, by density separation in sodium chloride. The weights of these blue, white and transparent fragments varied between 10 and 350 μg. Polymer types were identified by comparing the resulting pyrograms with those obtained from the pyrolysis of selected standard polymers. The particles consisted of polyethylene (PE), polypropylene, polystyrene, polyamide, chlorinated PE and chlorosulfonated PE. The polymers contained diethylhexyl phthalate, dibutyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethyl phthalate, benzaldehyde and 2,4-di-tert-butylphenol. Sequential Py-GC/MS was found to be an appropriate tool for identifying marine microplastics for polymer types and OPAs. The IPAs identified were titanium dioxide nanoparticles (TiO2-NPs), barium, sulphur and zinc. When polymer-TiO2 composites are degraded in the marine environment, TiO2-NPs are probably released. Thus, marine microplastics may act as a TiO2-NP source, which has not yet been considered.
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