Turbulent mixing in the ocean exerts an important control on the rate and structure of the overturning circulation. However, the balance of processes underpinning this mixing is subject to significant uncertainties, limiting our understanding of the overturning\'s deep upwelling limb. Here, we investigate the hitherto primarily neglected role of tens of thousands of seamounts in sustaining deep-ocean upwelling. Dynamical theory indicates that seamounts may stir and mix deep waters by generating lee waves and topographic wake vortices. At low latitudes, stirring and mixing are predicted to be enhanced by a layered vortex regime in the wakes. Using three realistic regional simulations spanning equatorial to middle latitudes, we show that layered wake vortices and elevated mixing are widespread around seamounts. We identify scalings that relate mixing rate within seamount wakes to topographic and hydrographic parameters. We then apply such scalings to a global seamount dataset and an ocean climatology to show that seamount-generated mixing makes an important contribution to the upwelling of deep waters. Our work thus brings seamounts to the fore of the deep-ocean mixing problem and urges observational, theoretical, and modeling efforts toward incorporating the seamounts\' mixing effects in conceptual and numerical ocean circulation models.

Plutonium, as well as fission products such as 137Cs, had been released into the earth environment in 1945 after the first atmospheric nuclear explosion of plutonium bomb in the desert of New Mexico (USA, July 16) and later over Nagasaki (August 9), followed then by many other explosions. Thus, plutonium cycling in the atmosphere and ocean has become a major public concern as a result of the radiological and chemical toxicity of plutonium. However, plutonium isotopes and 137Cs are important transient tracers of biogeochemical and physical processes in the environment, respectively. In this review, we show that both physical and chemical approaches are needed to comprehensively understand the behaviors of plutonium in the atmosphere and ocean. In the atmosphere, plutonium and 137Cs attach with aerosols; thus, plutonium moves according to physical and chemical processes in connection with aerosols; however, since plutonium is a chemically reactive element, its behavior in an aqueous environment is more complicated, because biogeochemical regulatory factors, in addition to geophysical regulatory factors, must be considered. Meanwhile, 137Cs is chemically inert in aqueous environments. Therefore, the biogeochemical characteristics of plutonium can be elucidated through a comparison with those of 137Cs, which show conservative properties and moves according to physical processes. Finally, we suggest that monitoring of both plutonium and 137Cs can help elucidate geophysical and biogeochemical changes from climate changes.

BACKGROUND: Trace metals such as iron, nickel, copper, zinc, and cadmium (Fe, Ni, Cu, Zn, and Cd) are essential micronutrients (and sometimes toxins) for phytoplankton, and the analysis of trace-metal stable isotopes in seawater is a valuable tool for exploring the biogeochemical cycling of these elements in the ocean. However, the complex and often time-consuming chromatography process required to purify these elements from seawater has limited the number of trace-metal isotope samples which can be easily processed in biogeochemical studies. To facilitate the trace-metal stable isotope analysis, here, we describe a new rapid procedure that utilizes automated chromatography for extracting and purifying Ni and Cu from seawater for isotope analysis using a prepFAST-MC™ system (Elemental Scientific Inc.).
RESULTS: We have tested the matrix removal effectiveness, recoveries, and procedural blanks of the new purification procedure with satisfactory results. A nearly complete recovery of Ni and a quantitative recovery of Cu are achieved. The total procedural blanks are 0.33 ± 0.24 ng for Ni and 0.42 ± 0.18 ng for Cu, which is negligible for natural seawater samples. The new procedure cleanly separates Ni and Cu from key seawater matrix elements that may cause interferences during mass spectrometry analysis. When the new procedure was used to purify seawater samples for Ni and Cu stable isotope analysis by multi-collector ICP-MS, we achieved an overall uncertainty of 0.07 ‰ for δ60Ni and 0.09 ‰ for δ65Cu (2 SD). The new purification procedure was also tested using natural seawater samples from the South Pacific, for comparison of δ60Ni and δ65Cu achieved in the same samples purified by traditional hand columns. Both methods produced similar results, and the results from both methods are consistent with analyses of δ60Ni and δ65Cu from other ocean locations as reported by other laboratories.
CONCLUSIONS: This study presents a new rapid procedure for seawater stable-metal isotope analysis by automating the chromatography step. We anticipate that the automated chromatography described here will facilitate the rapid and accurate analysis of seawater δ60Ni and δ65Cu in future studies, and may be adapted in the future to automate chromatographic purification of Fe, Zn, and Cd isotopes from seawater.

Microplastics pollution is killing human life, contaminating our oceans, and lasting for longer in the environment than it is used. Microplastics have contaminated the geochemistry and turned the water system into trash barrel. Its detection in water is easy in comparison to soil and air so the attention of researchers is focused on it for now. Being very small in size, microplastics can easily cross the water filtration system and end up in the ocean or lakes and become the prospective challenge to aquatic life. This review piece provides the hot research theme and current advances in the field of microplastics and their eradication through the virtual world of artificial intelligence (AI) because Microplastics have confrontation with clean water tactics.

Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film\'s surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.

Chirality, a fundamental property of matter, is often overlooked in the studies of marine organic matter cycles. Dihydroxypropanesulfonate (DHPS), a globally abundant organosulfur compound, serves as an ecologically important currency for nutrient and energy transfer from phytoplankton to bacteria in the ocean. However, the chirality of DHPS in nature and its transformation remain unclear. Here, we developed a novel approach using chiral phosphorus-reagent labeling to separate DHPS enantiomers. Our findings demonstrated that at least one enantiomer of DHPS is present in marine diatoms and coccolithophores, and that both enantiomers are widespread in marine environments. A novel chiral-selective DHPS catabolic pathway was identified in marine Roseobacteraceae strains, where HpsO and HpsP dehydrogenases at the gateway to DHPS catabolism act specifically on R-DHPS and S-DHPS, respectively. R-DHPS is also a substrate for the dehydrogenase HpsN. All three dehydrogenases generate stable hydrogen bonds between the chirality-center hydroxyls of DHPS and highly conserved residues, and HpsP also form coordinate-covalent bonds between the chirality-center hydroxyls and Zn2+, which determines the mechanistic basis of strict stereoselectivity. We further illustrated the role of enzymatic promiscuity in the evolution of DHPS metabolism in Roseobacteraceae and SAR11. This study provides the first evidence of chirality\'s involvement in phytoplankton-bacteria metabolic currencies, opening a new avenue for understanding the ocean organosulfur cycle.

Salmon lice, Lepeophtheirus salmonis (family Caligidae), are ectoparasites that have negatively impacted the salmon aquaculture industry and vulnerable wild salmon populations. Researchers have studied salmon lice to better understand their biology to develop effective control strategies. In this study, we updated the chromosome-level reference genome assembly of the Pacific subspecies of L. salmonis using Hi-C data. The previous version placed contigs/scaffolds using an Atlantic salmon louse genetic map. By utilizing Hi-C data from Pacific salmon lice, we were able to properly assign locations to contigs/scaffolds previously unplaced or misplaced. This resulted in a more accurate genome assembly and a more comprehensive characterization of the sex chromosome unique to females (W). We found evidence that the same ZW-ZZ mechanism is common in both Atlantic and Pacific subspecies of salmon lice using PCR assays. The W chromosome was approximately 800 kb in size, which is ∼30 times smaller than the Z chromosome (24 Mb). The W chromosome contained 61 annotated genes, including 32 protein-coding genes, 27 long noncoding RNA (lncRNA) genes, and 2 pseudogenes. Among these 61 genes, 39 genes shared homology to genes found on other chromosomes, while 20 were unique to the W chromosome. Two genes of interest on the W chromosome, prohibitin-2 and kinase suppressor of ras-2, were previously identified as potential sex-linked markers in the salmon louse. However, we prioritized the 20 unique genes on the W chromosome as sex-determining candidates. This information furthers our understanding of the biology of this ectoparasite and may help in the development of more effective management strategies.

UNASSIGNED: Surfing is an increasingly popular sport with a high propensity for both traumatic and atraumatic injuries.
UNASSIGNED: To analyze the trends, etiologies, and diagnoses of lower extremity orthopaedic-related surfing injuries presenting to United States (US) emergency departments (EDs) within a 21-year study period.
UNASSIGNED: Descriptive epidemiology study.
UNASSIGNED: The National Electronic Injury Surveillance System database was queried for data on lower extremity surfing injuries presenting to US EDs from January 1 to December 31, 2022. Data collected included year, injury mechanism, injury location, diagnosis, and disposition. The raw data were used to calculate national estimates (NEs) based on each hospital\'s assigned statistical sample weight. Linear regressions were performed to analyze annual trends.
UNASSIGNED: A total of 776 lower extremity surfing injuries were included (NE = 49,218 injuries). The mean age of the patients was 29.4 ± 13.6 years. The most common injured areas were the foot (NE = 17,411; 35.4%), lower leg (NE = 8673, 17.6%), and knee (NE = 8139; 16.5%). The most common mechanism of injury was impact with board (NE = 17,144; 34.8%), and the most common fracture locations were the lower leg (NE = 1195; 29.5%), ankle (NE = 1594; 24.5%), and foot (NE = 1495; 23.0%). There were statistically significant decreases in weighted estimates for lower extremity surfing injuries by 108 per year (P < .001), for lacerations by 76 per year (P < .001), and for sprains by 18 per year (P = .01). Impact-with-board injuries decreased by 59 injuries per year (P < .001) and constituted 63.5% of lacerations and 12.1% of fractures. Only 3.9% of patients were admitted for hospitalization.
UNASSIGNED: There was a decreasing trend in lower extremity surfing injuries presenting to US EDs during the 21-year study period.

UNESCO\'s Intergovernmental Oceanographic Commission launched the United Nations Decade of Ocean Science for Sustainable Development in 2021 to boost global and sustainable Ocean governance. The initiative resulted from historical and political dynamics at the global and lower political scales, with maritime environmental and economic concerns becoming more prominent in 2010. The Ocean Decade\'s pillars include science and research, sustainability, conservation, and bridging gaps for a global Ocean-Climate-Biodiversity nexus. The Sustainable Development Goals recognized the importance of oceans and marine resources, and the Ocean was officially perceived as a determining factor of Climate Change at CoP 21 in 2015. Portugal has built integrated and far-reaching policies for ocean governance, including significant involvement with an international perspective since the Lisbon World Exhibition in 1998. In addition, the national government established a Ministry of the Sea in 2015 to re-develop relations with its maritime space. This article analyzes and compares the discourse of the United Nations\' Sustainable Development Goals reports and the Portuguese government programs (2005-2022) to explore the prominent trends in Portuguese Ocean governance discourse and how global and national perspectives interact. Through this case study, the research aims to develop insights into the multiscalar impacts of promoting global and sustainable Ocean governance and its interaction with national perspectives.

Understanding the characteristics and structure of populations is fundamental to comprehending ecosystem processes and evolutionary adaptations. While the study of animal and plant populations has spanned a few centuries, microbial populations have been under scientific scrutiny for a considerably shorter period. In the ocean, analyzing the genetic composition of microbial populations and their adaptations to multiple niches can yield important insights into ecosystem function and the microbiome\'s response to global change. However, microbial populations have remained elusive to the scientific community due to the challenges associated with isolating microorganisms in the laboratory. Today, advancements in large-scale metagenomics and metatranscriptomics facilitate the investigation of populations from many uncultured microbial species directly from their habitats. The knowledge acquired thus far reveals substantial genetic diversity among various microbial species, showcasing distinct patterns of population differentiation and adaptations, and highlighting the significant role of selection in structuring populations. In the coming years, population genomics is expected to significantly increase our understanding of the architecture and functioning of the ocean microbiome, providing insights into its vulnerability or resilience in the face of ongoing global change. Video Abstract.