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Heavy metals that are adhered to the surfaces of microplastics in the natural marine environment pose potential threats to marine life. However, little is known about their adsorption mechanisms and composite risks. This study collected seawater, suspended particulate matter (SPM), plankton, and microplastic samples from the waters surrounding Hong Kong, established a method for analyzing 13 heavy metals in the plastisphere, and explored the extrinsic and intrinsic sources of the heavy metals by analyzing natural matrices (seawater, SPM, and plankton) and anthropogenic plastics. We found that heavy metals in the plastisphere were significantly affected by the surrounding matrices, as indicated by its positive correlations with the heavy metals in SPM and plankton at most of the sampling sites. Heavy metals in plankton usually occurred as traces of oxides such as As2O3 and ZnO. The partition coefficients of the studied heavy metals between seawater and the plastisphere were identical to those between the SPM and the plastisphere. No correlations were found between the concentrations of heavy metals in the plastisphere and the heavy metal concentrations, masses, quantities, or surface areas of the microplastics, although some polymer types contained extremely high Cd (676 mg/kg), Pb (1,742 mg/kg), and Zn (1,712 mg/kg) concentrations. Only the Cr, Cu, and Ni concentrations were positively correlated with the specific surface area of the microplastics. A cluster analysis showed that Cr, Cu, and Ni were derived from anthropogenic sources, indicating that adventive heavy metals could be adsorbed by plastics with large specific surface areas. We also established a new composite risk assessment method for heavy metals and microplastics that leverages the specific surface areas of microplastics. The assessment results showed that Cd from Tolo Harbor had a strong ecological risk, while As and Cd from the eastern waters off Hong Kong had moderate composite ecological risks.

Heavy metal resistance (Cu, Zn, Fe, Cr, Pb, Cd) and removal capacities of 19 selected actinobacteria strains were performed in order to investigate their applicability as bioremediators for polluted areas. Streptomyces sp. WR1L1S8 was used in the present investigation as heavy metals removing strain, which was isolated from inner tissu of the marine brown algae Fucus sp., and identified based on polyphasic and molecular characterization. The results showed that WR1L1S8 could successfully remove Fe2+, Cu2+ and Zn2+ by 60.74%, 42% and 39.02%, respectively, using Atomic Absorption Spectroscopy (AAS) analysis. The strain WR1L1S8 had a considerable tolerance to initial Cu2+ with a minimum inhibitory concentration value recorded at 250 mg L−1. Rotatable Central Composite Design (CCD) was used to optimize the copper removal yield using nutrient broth in batch experiment studying the influence of four operating parameters: incubation time, stirring speed, inoculum size and percentage of seawater. The optimal conditions were found at incubation time of 9 days under 114.9 rpm of a stirring speed, 18 agar cylinders as inoculum and 80.75% of seawater reaching a removal capacity of 75.24% which correspond to 29.65% increase compared with the non-optimized conditions. WR1L1S8 exhibited a promising potential for copper removal from aqueous solutions.

This study sought to clarify whether suspended particles containing high Cu concentrations are present in the sea-surface microlayer (S-SML). For this reason, suspended particles (10–2000 μm) in the S-SML were collected periodically from a ship mooring pond during 2018–2020, and the acid-soluble Cu concentration in the suspended particles was measured as particulate Cu (P-Cu). The highest concentration of P-Cu in the S-SML of the pond was 75 μg L−1 with a 90th percentile value of 2.5 μg L−1. This is below P-Cu values reported for the S-SML in North American ports, but 140 times higher than this found in bulk seawater in the Atlantic Ocean. The highest P-Cu concentration in the S-SML of non-organism (abiotic) origin was 17 μg L−1, and the abiotic P-Cu to P-Cu ratio varied from 0.2 to 100%, likely depending on the quality and quantity of biogenic material in the S-SML samples. It is assumed that the S-SML particles examined here contain high Cu concentrations originating from ship antifouling paints.

With the rapid increase in the demand for lithium as an energy-critical element, the recovery of Li+ ions from seawater is a worldwide challenging issue. Herein, we propose a new facile and fast selective recovery approach of Li+ using an Al3+-crosslinked poly(N-isopropylacrylamide) (PNIPAAm)/alginate (Alg) (PNP/Alg(Al)) adsorbent. The in situ TEM images indicate that Alg–Al3+ coordination is reorganized via the rearrangement of PNIPAAm and Alg networks, as the temperature increases. The reorganization eventually leads to the formation of polycrystalline structure. The in situ FTIR results exhibit that PNP/Alg(Al) composite has peculiar phase transitions, which includes a retrogressive phase change from hydrophobic to hydrophilic. The synergetic effect of the strong repulsion force of Al3+ ions and the attractive force of negatively charged polymeric chains enables the efficient adsorption of Li+ ions with a low affinity from Li-spiked seawater. 7.3% of Li+ ions are recovered from Li-spiked seawater although the concentration of Li-spiked seawater is very high. In addition, Li+ ions can be extracted from PNP/Alg(Al) composite with the use of a small thermal energy. The proposed thermoresponsive IPN gel provides a strong potential in practical applications for Li+ recovery as an innovative energy-material strategy.

Studies on the impact of ocean acidification on marine organisms involve exposing organisms to future acidification scenarios as projected for open ocean, which has limited relevance for coastal calcifiers. Characterization of reaction norms across a range of pH and identification of tipping points beyond which detrimental effects are observed has been limited and focus on only a few macro-physiological traits. Here we filled this knowledge gap by developing a framework to analyze the broad macro-physiological and molecular responses over a wide pH range of juvenile Pacific oyster, a model species for which the tolerance threshold to acidification remains unknown. We identify low tipping points for physiological traits at pH 7.3-6.9 that coincide with a major reshuffling in membrane lipids and transcriptome. In contrast, shell parameters exhibit effects with pH drop well before tipping points, likely impacting animal fitness. These findings were made possible by the development of an innovative methodology to synthesize and identify the main patterns of variations in large -omic datasets, fit them to pH and identify molecular tipping-points. We propose the application of our framework broadly to the assessment of effects of global change on other organisms.

The development of novel materials with ion-selective nanochannels has introduced a new technology for harvesting salinity gradient (blue) energy, namely nanopore power generators (NPG). In this study, we perform a comprehensive analysis of the practical performance of NPG in both coupon-size and module-scale operations. We show that although NPG membrane coupons can theoretically generate ultrahigh power density under ideal conditions, the resulting power density in practical operations at a coupon scale can hardly reach 10 W·m−2 due to concentration polarization effects. For module-scale NPG operation, we estimate both the power density and specific extractable energy (i.e., extractable energy normalized by the total volume of the working solutions), and elucidate the impact of operating conditions on these two metrics based on the interplay between concentration polarization and extent of mixing of the high- and low-concentration solutions. Further, we develop a modeling framework to assess the viability of an NPG system. Our results demonstrate that, for NPG systems working with seawater and river water, the gross specific extractable energy by the NPG system is very low (~0.1 kW·h·m−3) and is further compromised by the parasitic energy consumptions in the system (notably, pumping of the seawater and river water solutions and their pretreatment). Overall, NPG systems produce very low net specific extractable energy (

Complex assemblages of microbes in the surface ocean are responsible for approximately half of global carbon fixation. The persistence of high taxonomic diversity despite competition for a small suite of relatively homogeneously distributed nutrients, that is, 'the paradox of the plankton', represents a long-standing challenge for ecological theory. Here we find evidence consistent with temporal niche partitioning of nitrogen assimilation processes over a diel cycle in the North Pacific Subtropical Gyre. We jointly analysed transcript abundances, lipids and metabolites and discovered that a small number of diel archetypes can explain pervasive periodic dynamics. Metabolic pathway analysis of identified diel signals revealed asynchronous timing in the transcription of nitrogen uptake and assimilation genes among different microbial groups-cyanobacteria, heterotrophic bacteria and eukaryotes. This temporal niche partitioning of nitrogen uptake emerged despite synchronous transcription of photosynthesis and central carbon metabolism genes and associated macromolecular abundances. Temporal niche partitioning may be a mechanism by which microorganisms in the open ocean mitigate competition for scarce resources, supporting community coexistence.

Sedimentary rocks and minerals formed during the final two-hundred million years of the Archean Eon (2.7 to 2.5 billion years ago, or Ga) are more depleted in 56Fe than at any other time in Earth’s past. Three hypotheses are proposed to explain these 56Fe depletions: (1) a very negative late-Archean seawater δ56Fe value, (2) “shuttling” of isotopically light Fe across the chemocline in redox-stratified settings, and (3) pyrite formation in an Fe(II)-rich ocean. Each of these scenarios has different implications for the initial oxidation of Earth’s surface, the climax of which – the Great Oxidation Event – immediately post-dates the appearance of these 56Fe depletions in the rock record. To help inform this debate, we measured the Fe isotope ratios of 120 shale and pyrite samples from Western Australia (Mt. McRae Shale and Jeerinah Formation) and South Africa (Klein Naute Formation) deposited between ∼2.65 Ga and ∼2.50 Ga. As in previous studies, we also find very strong sedimentary 56Fe depletions, to as low as δ56Fe = −2.06 ± 0.08‰ in bulk shales and δ56Fe = −2.31 ± 0.08‰ in pyrite. Some, but not all, of the severest 56Fe depletions appear alongside evidence of an Fe shuttle and local pyrite formation. These processes need not be mutually exclusive, and some combination of them likely played a partial, probably faciliatory role in driving some strong 56Fe depletions in our dataset. Most interestingly, and with little exception, the severest 56Fe depletions appear in samples deposited farther from shore under H2S-rich and anoxic (“euxinic”) conditions. We find it difficult to explain this connection without invoking the persistent presence of a very negative global seawater δ56Fe value during the latest Archean, one that was most consistently captured in sediments formed in distal euxinic settings. In order to impart this isotopic effect on seawater, the global seawater Fe(II) reservoir needed to have been partially oxidized during at least the final few hundreds of millions of years leading up to the Great Oxidation Event. Our new data add support to the idea that Earth’s initial oxidation was a long and protracted process rather than a rapid event.

The present work deals with a cost-effective removal of methylene blue (MB) dye utilizing a low-cost adsorbent, seawater based geopolymer (SW-GP) in the treatment of wastewater. It is prepared from different industrial by-products as raw materials such as coal fly ash (Class F), bottom ash (BA), and Ground Granulated Blast-furnace Slag (GGBS) by factorial mix design. The adsorbent was characterized using the Fourier-Transform Infra-Red spectroscopy (FT-IR) to identify the major functional groups. The percentage of elemental composition was calculated by X-ray fluorescence (XRF) analysis. The Scanning Electron Microscope (SEM) analysis confirms the presence of mullite and quartz in the adsorbent. The surface area was calculated by the Brunauer–Emmett–Teller (BET) analysis as 11.85 m2/g and pore size distribution was calculated by the Barrett–Joyner–Halenda (BJH) model to be 0.025 cm3/g. At an optimum dosage (0.08 g/L) of the geopolymer, the efficiency of MB color removal i.e. the adsorption capacity of the adsorbent was found as 81.36% and 59.52 mg/g respectively. Seawater based geopolymer (SW-GP) performs as an efficient adsorbent because of its less energy consumption in synthesis, larger surface area, and longer thermal stability up to 800°C for the removal of methylene blue in an aqueous medium by adsorption process.

Polycyclic aromatic hydrocarbons (PAHs), as persistent toxic substances (PTS), have been widely monitored in coastal environment, including seawater and sediment. However, scientific monitoring methods, like ecological risk assessment and integrated biomarker response, still need massive researches to verify their availabilities. This study was performed in March, May, August and October of 2018 at eight sites, Yellow River estuary (S1), Guangli Port (S2), Xiaying (S3), Laizhou (S4), Inner Bay (S5), Outer Bay (S6), Hongdao (S7) and Hongshiya (S8) of Shandong Peninsula, China. The contents of 16 priority PAHs in local seawater and sediment were determined, by which ecological risk assessment risk quotient (RQ) for seawater and sediment quality guidelines (SQGs) were calculated to characterize the PAHs pollution. Meanwhile, multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints, including ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), sulfotransferase (SULT), superoxide dismutase (SOD) and lipid peroxidation (LPO), by which integrated biomarker response (IBR) was calculated to provide a comprehensive assessment of environmental quality. Taken together, these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected, and supported the integrated biomarker response as a useful tool for marine environmental monitoring, through its integration with SQGs.

In situ sensors are needed to further our understanding of phosphate flux dynamics in marine environments during short term events such as tidal cycles, algae blooms and runoff periods. Here, we present a fully automated in situ phosphate analyzer based on an inlaid microfluidic absorbance cell technology. The microfluidic device employs colorimetric absorbance spectrophotometry, using the phosphomolybdenum blue (PMB) assay modified by the addition of polyvinylpyrrolidone (PVP), to measure phosphate concentrations in seawater. Bench top calibrations were performed with both copper(II) sulfate dye and the PMB assay, as well as temperature sensitivity studies to characterize the sensor’s performance in a range of conditions. It achieves a limit of detection of 15.2 nM, a limit of quantification of 50.8 nM, and a high in situ precision with a relative standard deviation of less than 1.5% across three consecutive measurements. Two consecutive field deployments are conducted as assessments for its intended in situ applications. The sensor is first deployed from a pier at a depth of 6 m, with simultaneous bottle samples taken to perform cross-validation. It is next deployed on the Stella Maris testbed, a multi-sensor seabed platform (MSSP), 100 m offshore and 9 m deep in the inlet to the Bedford Basin in Nova Scotia, Canada. Over 300 successful phosphate measurements were acquired, showing the influence of the tidal cycle, and confirming the sensor’s viability in observing nutrient flux dynamics with nanomolar variations.

25 pages, 10 figures, 7 tables.-- This work is distributed under the Creative Commons Attribution 4.0 License, The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2021 is an update of the previous version, GLODAPv2.2020 (Olsen et al., 2020). The major changes are as follows: data from 43 new cruises were added, data coverage was extended until 2020, all data with missing temperatures were removed, and a digital object identifier (DOI) was included for each cruise in the product files. In addition, a number of minor corrections to GLODAPv2.2020 data were performed. GLODAPv2.2021 includes measurements from more than 1.3 million water samples from the global oceans collected on 989 cruises. The data for the 12 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but updated to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For this annual update, adjustments for the 43 new cruises were derived by comparing those data with the data from the 946 quality controlled cruises in the GLODAPv2.2020 data product using crossover analysis. Comparisons to estimates of nutrients and ocean CO2 chemistry based on empirical algorithms provided additional context for adjustment decisions in this version. The adjustments are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent with to better than 0.005 in salinity, 1% in oxygen, 2% in nitrate, 2% in silicate, 2% in phosphate, 4 μmolkg-1 in dissolved inorganic carbon, 4 μmolkg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5% in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments., The original data, their documentation, and DOI codes are available at the Ocean Carbon Data System of NOAA NCEI (https://www.ncei.noaa.gov/access/ocean-carbon-data-system/oceans/GLODAPv2_2021/, last access: 7 July 2021). This site also provides access to the merged data product, which is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/ttgq-n825 (Lauvset et al., 2021). These bias-adjusted product files also include significant ancillary and approximated data and can be accessed via https://www.glodap.info (last access: 29 June 2021). These were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2021 methods and provides a broad overview of the secondary quality control procedures and results, This research has been supported by EU Horizon 2020 through the EuroSea action (grant no. 862626), internal strategic funding from NORCE Climate, Prociencia/UERJ (grant 2019–2021), IEO RADIALES and RADPROF projects, the UK Climate Linked Atlantic Sector Science (CLASS) NERC National Capability Long-term Single Centre Science Programme(grant no. NE/R015953/1), the BOCATS2 (PID2019-104279GBC21) project funded by MCIN/AEI/10.13039/501100011033 and contributing toWATER:iOS CSIC PTI, the NOAA Global Observations and Monitoring Division (fund reference 100007298), the Office of Oceanic and Atmospheric Research of NOAA Global Observations and Monitoring Division (fund reference 100007298), the Office of Oceanic and Atmospheric Research of NOAA, the BONUS INTEGRAL project (grant no. 03F0773A), the Australian Antarctic Program Partnership and the Integrated Marine Observing System, EU Horizon 2020 action SO-CHIC (grant no. 821001), and the Initiative and Networking Fund of the Helmholtz Association through the project “Digital Earth” (grant no. ZT-0025)

Culture experiments are uniquely suited for uncovering the fundamental factors controlling skeletal geochemistry because it is possible to explore conditions beyond what is found in the modern ocean and to decouple parameters that co-vary in nature. We cultured juvenile individuals of a cold-water coral (Balanophyllia elegans) in a set of experiments that decoupled carbonate chemistry parameters over a wide range of pH, DIC, and [CO32−] values. Using a multi-element mixed spike isotope dilution method we then analyzed cultured skeletons for U/Ca, which has been proposed as a potential proxy for seawater pH and [CO32−], as well as Sr/Ca, and Mg/Ca. We find that U/Ca and Sr/Ca ratios in cultured B. elegans are most strongly correlated with solution DIC and not pH or [CO32−]. We also confirm previous observations that Metal/Calcium (Me/Ca) ratios follow the same correlated relationships between and among individuals across different experimental conditions. Interpretation of these robust Me/Ca patterns within the framework of a geochemical model of biomineralization allows us to identify two “rules” of skeletal growth for B. elegans. First, changes in seawater exchange rates can explain variability in B. elegans Me/Ca ratios, correlations between these ratios, and sensitivity of Me/Ca to changes in seawater carbonate chemistry. Second, our model best fits our data if we assume that calcifying fluid pH for B. elegans remains constant across widely varying experimental seawater compositions. Our study has implications for the recently developed Sr-U paleothermometer because it refines our understanding of the environmental parameters affecting this proxy. Our model further demonstrates that U/Ca is not a robust indicator of seawater pH or [CO32−]. Instead, U/Ca may record how calcifying fluid [CO32−] responds to changes in the environment or calcification dynamics, which may be useful in evaluating how corals respond to changes like ocean acidification. Measurements of U/Ca and additional Me/Ca ratios in other coral species, evaluated within a similar framework, may elucidate how those species respond to environmental change.

Some cancers have evolved the ability to spread from host to host by transmission of cancerous cells. These rare biological entities can be considered parasites with a host-related genome. Still, we know little about their specific adaptation to a parasitic lifestyle. MtrBTN2 is one of the few lineages of transmissible cancers known in the animal kingdom. Reported worldwide, MtrBTN2 infects marine mussels. We isolated MtrBTN2 cells circulating in the hemolymph of cancerous mussels and investigated their phenotypic traits. We found that MtrBTN2 cells had remarkable survival capacities in seawater, much higher than normal hemocytes. With almost 100% cell survival over three days, they increase significantly their chances to infect neighboring hosts. MtrBTN2 also triggered an aggressive cancerous process: proliferation in mussels was ~ 17 times higher than normal hemocytes (mean doubling time of ~ 3 days), thereby favoring a rapid increase of intra-host population size. MtrBTN2 appears to induce host castration, thereby favoring resources re-allocation to the parasites and increasing the host carrying capacity. Altogether, our results highlight a series of traits of MtrBTN2 consistent with a marine parasitic lifestyle that may have contributed to the success of its persistence and dissemination in different mussel populations across the globe.

Comparing measurements of the natural sea surface microlayer (SML) and artificial surface films made of Triton-X-100 and oleyl alcohol can provide a fundamental understanding of diffusive gas fluxes across the air–water boundary layers less than 1 mm thick. We investigated the impacts of artificial films on the concentration gradients and diffusion of oxygen (O2) across the SML, the thickness of the diffusive boundary layer (DBL), and the surface tension levels of natural seawater and deionized water. Natural and artificial films led to approximately 78 and 81% reductions in O2 concentration across the surfaces of natural seawater and deionized water, respectively. The thicknesses of the DBL were 500 and 350 µm when natural SML was added on filtered and unfiltered natural seawater, respectively, although the DBL on filtered seawater was unstable, as indicated by decreasing thickness over time. Triton-X-100 and oleyl alcohol at a concentration of 2000 µg L−1 in deionized water persistently increased the DBL thickness values by 30 and 26% over a period of 120 min. At the same concentration, Triton-X-100 and oleyl alcohol decreased the surface tension of deionized water from ~72 mN m−1 to 48 and 38 mN m−1, respectively; 47% recovery was recorded after 30 min with Triton-X-100, although low surface tension persisted for 120 min with oleyl alcohol. The critical micelle concentration values of Triton-X-100 ranged between 400 and 459 µg L−1. We, therefore, suggest that Triton-X-100 resembles natural SML because the reduction and partial recovery of the surface tension of deionized water with the surfactant resembles the behavior observed for natural slicks. Temperature and salinity were observed to linearly decrease the surface tension levels of natural seawater, artificial seawater, and deionized water. Although several factors leading to O2 production and consumption in situ are excluded, experiments carried out under laboratory-controlled conditions are useful for visualizing fine-scale processes of O2 transfer from water bodies through the surface microlayer.

Microcosmic experiments were performed under a simulated marine environment to investigate the natural attenuation of C9 aromatics using nine components (propylbenzene, isopropylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and indene). This research aims to assess the contribution of biodegradation and abiotic activity to total attenuation of C9 aromatics and ascertain the changes in the comprehensive toxicity of seawater in the natural environment. The process of natural attenuation indicates the agreement with pseudo-first-order kinetics for all nine components in microcosmic experiments. The half-lives of the nine main compounds in C9 aromatics ranged between 0.34 day and 0.44 day under optimal conditions. The experiments showed that the natural attenuation of nine aromatic hydrocarbons mainly occurred via abiotic processes. Seawater samples significantly inhibited the luminescence of P. phosphoreum (the luminescence inhibition ratio reached 100%) at the beginning of the experiment. In addition, the toxicity declined slowly and continued for 25 days. The attenuation kinetics and changes in toxicity could be applied to explore the natural attenuation of C9 aromatics in the marine environment.

International audience; High-precision triple oxygen isotope data on 40 water samples (5–10 923 m in depth) collected at the Challenger Deep of the Mariana Trench are reported in this study. The analyses at Laboratoire des Sciences du Climat et l’Environnement yield mean isotope values δ18O = −0.084 ± 0.224‰, δ17O = −0.061 ± 0.117‰, and 17O-excess = −17 ± 5 per meg, with standard deviations reported at 1σ. The range of δ18O (from −0.480 to 0.544‰) falls within records of the Global Seawater Oxygen-18 Database at the Mariana Trench. The average 17O-excess value at the Mariana Trench is more negative than the average 17O-excess value of −5 ± 4 (1σ) per meg in the only prior data set including deep ocean samples. The slope (λ) of the three-isotope plot of Mariana Trench water is 0.521 ± 0.003 (1σ), lower than λ of 0.528 ± 0.001 (1σ) for ocean water in the prior study. The new data set matches the prediction of the ocean isotope mass balance model, suggesting that it may represent a more appropriate ocean endmember for triple oxygen isotope thermometry. The 17O-excess of ocean water with respect to Vienna Standard Mean Ocean Water (VSMOW) is recognized to be a necessary correction in quantifying gross oxygen productivity of euphotic regions and relative humidity of moisture source regions.

The application of Ca isotopic analysis in biomedical studies has great potential to identify changes in Ca metabolism and bone metabolism. Reliable measurement of Ca isotope-amount ratios is challenging considering limited Ca amounts and significant procedural blank levels. In this study, Ca purification was performed using the DGA Resin, optimized for low procedural blanks and separation of Ca from matrix elements and isobaric interferences (Na, Mg, K, Ti, Fe, Ba), while maintaining quasi-quantitative recoveries which are sufficient since a 42Ca–48Ca double-spike (DS) was applied. Ca isotopic analysis was performed using multicollector thermal ionization mass spectrometry (MC TIMS). The obtained procedural Ca blank of ≤10 ng enables processing of limited Ca amounts down to 670 ng. Data reduction of the measured Ca isotope-amount ratios was performed using an in-house developed software solving the DS algorithm. Data quality was improved by extension of equilibration time of the sample-DS mixture and implementation of a normalization strategy for raw isotopic data. The reported δ(44Ca/40Ca)NIST SRM 915a of NIST SRM 915a processed as a sample was found to be 0.01 ‰ ± 0.08 ‰ (2 SD, n = 15). Ca isotope-amount ratios of the reference material NIST SRM 1400 (bone ash), NIST SRM 1486 (bone meal), GBW07601 (human hair), and IAPSO (seawater) were in good agreement within uncertainty with literature data. Novel data on additional reference materials for biological tissues (hair) is presented, which might indicate a potential fractionation of Ca incorporated into hair tissue when compared to the blood pool.

Human activities are changing the Arctic environment at an unprecedented rate resulting in rapid warming, freshening, sea ice retreat and ocean acidification of the Arctic Ocean. Trace gases such as nitrous oxide (N2O) and methane (CH4) play important roles in both the atmospheric reactivity and radiative budget of the Arctic and thus have a high potential to influence the region’s climate. However, little is known about how these rapid physical and chemical changes will impact the emissions of major climate-relevant trace gases from the Arctic Ocean. The combined consequences of these stressors present a complex combination of environmental changes which might impact on trace gas production and their subsequent release to the Arctic atmosphere. Here we present our current understanding of nitrous oxide and methane cycling in the Arctic Ocean and its relevance for regional and global atmosphere and climate and offer our thoughts on how this might change over coming decades. Supplementary Information The online version contains supplementary material available at 10.1007/s13280-021-01633-8.

The Co@NCNTs/Si pillars with channels is assemble to a suitable pure water gathering device, which is applied in seawater desalination and sewage purification to produce pure water by utilizing solar energy. High-efficiency utilization of solar energy to generate water vapor is popular, recyclable, and environmentally friendly for seawater desalination and sewage purification, helping to alleviate the global water shortage crisis. Here, we report an efficient and simple method to prepare a three-dimensional (3D) evaporator for steam generation by harnessing the power of the sun. This evaporation is composed of one-dimensional (1D) cobalt embedded and nitrogen doped carbon nanotubes (Co@NCNTs) and 3D silicon pillars array structure (Si pillars). The Co@NCNTs/Si pillars shows a wide light absorption range provided by carbon nanotubes and a long light absorption path because of the silicon pillars. The surface temperature of the sample rises rapidly in 1.5 min and exceed 80 °C under solar illumination of one sun. The water evaporation can be high as 1.21 kg m−2 h−1 under one sun irradiation (1 kW/m2) with the energy efficiency up to 82.4%. This scalable Co@NCNTs/Si pillars can prepare pure water from seawater and sewage, where the removal rate of ions in seawater and pollutants in sewage is similar to 100%. Based on our research, this multistage three-dimensional structure is a simple and efficient novel photothermal material for extensive seawater desalination and sewage purification.

Steel materials employed in severe conditions including strong corrosion, high load and multi-factor coupling damages can easily cause incredible degradation until failure, and the protective CrN-based coatings should be one of promising candidates to relieve those damages for the steel equipment or components. In present paper, the monolayer CrAlN and multilayer Cr/CrAlN coatings were successfully deposited on steel substrates by multi-arc ion technology, and their microstructure, mechanical, tribological and corrosion performances were systematically investigated. The results show that the special multilayer Cr/CrAlN coating could possess much better load-bearing capacity and wear resistance than that of monolayer CrAlN coating, which was due to the facts that the multilayer architecture can effectively release the internal stress and inhibit the expansion of defects. Particularly, the multilayer interfaces could effectively prevent the aggressive medium in seawater infiltrating into the inside of coating, and thus the multilayer Cr/CrAlN coating could have higher corrosion resistance compared to monolayer CrAlN coating. As a result, this multilayer Cr/CrAlN coating could achieve excellent combined performances, indicating that it has greatly potential application as protective coating in seawater.

Uranium extraction from seawater is of strategic significance for nuclear power generation. Amidoxime-based functional adsorbents play indispensable roles in the recovery of seawater uranium with high efficiency. Nevertheless, balancing the adsorption capacity and selectivity is challenging in the presence of complicated interfering ions especially vanadium. Herein, a polyarylether-based covalent organic framework functionalized with open-chain amidoxime (COF-HHTF-AO) was synthesized with remarkable chemical stability and excellent crystallinity. Impressively, the adsorption capacity of COF-HHTF-AO towards uranium in natural seawater reached up to 5.12 mg/g, which is 1.61 times higher than that for vanadium. Detailed computational calculations revealed that the higher selectivity for uranium over vanadium originated from the specific bonding nature and coordination pattern with amidoxime. Combining enhanced adsorption capacity, excellent selectivity and ultrahigh stability, COF-HHTF-AO serves as a promising adsorbent for uranium extraction from the natural seawater.

Despite its status as a critical metal in the EU and the U.S., the geochemical behavior of gallium (Ga) in the Earth’s surface environment is not yet well constrained, which is in marked contrast to its geochemical partner aluminum (Al). Especially hydrogenetic ferromanganese crusts which may represent a potential future unconventional resource of critical metals, are surprisingly underexplored with regard to their Ga-Al systematics. This study presents the first data on the Ga-Al pair in hydrogenetic Fe-Mn crusts from various locations in the Pacific Ocean and from the Rio Grande Rise in the SW Atlantic. We also provide Ga-Al data for certified reference materials for Fe-Mn nodules NOD-P-1, NOD-A-1, and JMn-1. Our results also show that marine hydrogenetic Fe-Mn crusts cannot be considered an unconventional Ga resource, in marked contrast to several other critical metals. Aluminum and Ga concentrations in these precipitates are not controlled by detrital components. Both elements show a geochemical behavior comparable to that of the hydroxide-dominated elements Zr and Hf during scavenging from ambient seawater by hydrogenetic Fe-Mn crusts. The Ga/Al mass ratios of Atlantic (0.10–0.16 g/kg) and Pacific crusts (0.18–1.2 g/kg) are about one and a half orders of magnitude lower than those of respective ambient seawater and mimic the inter-oceanic fractionation of the Ga-Al pair between these two ocean basins. Without exception, the Atlantic Fe-Mn crusts show lower Ga/Al ratios than the Pacific crusts. The systematically lower Ga/Al ratios of the crusts relative to those of seawater reveal preferential scavenging of Al relative to Ga during the formation of Fe-Mn crusts. This is in line with previous studies that reported a higher particle reactivity of Al compared to Ga in the marine environment. However, this fractionation trend contradicts predictions based on a simplified model commonly used to approximate trace element scavenging by marine metal (hydr)oxides based on hydrolysis constants, which favors Ga enrichment relative to Al as the hydrolysis constant of Ga is higher than that of Al. The observed Ga-Al fractionation may be related to the preferential retention of Al compared to Ga on the surface of the Fe-Mn (oxyhydr)oxides because in contrast to Ga, desorption of Al is characterized by very slow reaction kinetics or is even irreversible. Alternatively, stronger organic complexation of dissolved Ga than Al in seawater (which is supported by the stability constants of various organic Ga and Al complexes) and the resulting preferential retention of Ga over Al in solution by dissolved organic ligands may be another viable mechanism to explain the observed Ga-Al fractionation between hydrogenetic Fe-Mn crusts and seawater. While more experimentally determined thermodynamic data are necessary, the rather consistent difference between hydrogenetic Fe-Mn crusts and ambient seawater supports an important role of organic ligands in the chemical speciation of Ga in seawater.

Coastal wetlands reclamation is facing the problem of salinization. Along with the alternation of ecosystem status, studying the following effect on soil properties becomes emergency. Here we reported the pH, salinity and elemental content (mainly metals) variation affected by the vegetation situations, water sources and geographic positions. The results showed that vegetation could lead the pH and salinity of seawater zones closer to that of freshwater zones in both spatial and time scales. Spartina alterniflora (SA) was the most efficient species among the investigated plants, causing decreases of 0.15–0.69 in pH and 2.250–3.821 in salinity. This result might be caused by the absorption of Ca and K from salt marshes by SA and Suaeda salsa (SS), due to the fact that the component content of calcium (all reduced to approximate one-third) and potassium (reduced in some samples) both decreased. Meanwhile, vegetation could improve soil in seawater zones in Fe content with no extra negative influences in elemental analysis. Thus, ecological engineered vegetation indicated great potential in alternating coastal salt marshes to favorable wetlands or farmlands with almost primitive ecosystem. The results might be significant for ecological engineering and agricultural management in future.

The abundances and isotope compositions of molybdenum (Mo) and uranium (U) in ancient sediments are promising tracers of the redox state of the past ocean, whose basis lies in the environmentally dependent Mo and U isotope signatures in modern oceanic settings. Despite their dominance in oceanic budgets, the controls on the Mo-U systematics of upwelling margin sediments remain to be fully understood. Here we present a comprehensive sediment-porewater Mo and U isotope study in the Benguela upwelling system off Namibia, including the first dataset incorporating coupled Mo-U abundance and isotope analysis of both solid authigenic phases and porewaters. The investigated stations represent shelf-to-slope settings, which lie on the upper edge, within and below the oxygen minimum zone (OMZ) of the South Atlantic. The sediments across all stations share similar characteristics: both Mo and U show increasing authigenic enrichment with depth, coupled to an overall decrease in δ98Moauth (from ~2.0‰ to 1.3‰ and from ~2.0‰ to 0.3‰) and increase in δ238Uauth (from −0.18‰ to 0.05‰ and from −0.34‰ to −0.21‰). Nevertheless, the extents of Mo and U enrichment and associated isotopic fractionations display spatial variability across the OMZ, reflecting variations in local sedimentary redox conditions. Porewater Mo and U concentration patterns are more complex, exhibiting peaks in Mo and U abundance well in excess of seawater (up to 8 times seawater for Mo) associated with correlated shifts in isotope composition. As a result, porewaters exhibit a wide range in isotope compositions, between 0.90‰ and 2.79‰ for δ98Mo and between −1.74‰ and 0.26‰ for δ238U. Porewater gradients at the time of sampling are inconsistent with diffusion downwards across the sediment–seawater interface as a means of enrichment of the sediment-porewater system. Though these sampled conditions may represent only a snapshot, so that periodically more reducing conditions could lead to concentration gradients that do permit downward diffusion, the data are also readily explained by addition of Mo and U to the sediment-porewater system in particulate form, also under more reducing conditions than at the time of sampling. For example, sequestration of Mo and U to particulate matter as a result of the presence of intermittent sulfide, either in bottom water or in porewater right at the sediment–water interface, explains much of the geochemical and isotope data. The data thus suggest that the early diagenetic enrichment of Mo and U in sediments of upwelling margins is strongly governed by temporal redox fluctuations. Early diagenesis under these dynamic redox conditions on the Namibian upwelling margin are strongly reflected in Mo-U co-variation patterns, as well as anti-correlations between authigenic δ98Mo and δ238U in sediments. Overall, our new data demonstrate that early diagenetic processes on open-marine continental margins reproduce patterns previously observed for coupled Mo-U isotope systematics in restricted and semi-restricted basins, but via a different set of processes and with important implications for the use of such a coupled approach in the study of ancient marine anoxia.

While performing various steps for exploration and exploitation of geothermal resources, the applications of geochemical methods are pivotal for reservoir characteristics evaluation. It is used concurrently with geological and hydro-geological appraisals to supplement available information regarding the prospectively of the region of investigation at the relatively low cost compared to geophysical methods or drilling. Temperature range of 40 °C to 47 °C is demonstrated by the study area comprising of several thermal water manifestations. Studies from existing wells and surveys have suggested the presence of a sizable low enthalpy geothermal resource in the field. One of the most prominent uses of geochemical sampling is the determination of subsurface temperatures using Geothermometry. In this study, commonly accepted concepts of cationic and Silica Geothermometry have been applied to understand conditions in the reservoir. Interpretation of the data has given us some input on the reservoir characteristics like reservoir temperature, mixing process and multiple fluid origins. In Dholera geothermal field for determination of variation in hydrochemical facies and understanding of the advancement of the hydrochemical forms, the current research additionally imagines the significance of graphical portrayals like Piper chart, Scholler and so forth individually. The seawater intrudes the composition of water shows the reservoir. The physio-chemical properties of the water also influence exploitation strategies.

Design of rational photoabsorbers is a promising approach to produce drinking water. Herein, a highly efficient and scalable wood-based photoabsorber device composed of poplar wood as a substrate coated with FeNi with mole ratio of Fe/Ni = 85% and reduced graphene oxide (RGO) as top and bottom layers, respectively was designed for the interfacial solar desalination of seawater and heavy metal removal as a sorbent. Benefiting from high sunlight utilization and rapid water transport, high photothermal conversion fluxes of 1.50 and 4.77 kg m−2h−1 were achieved by the most efficient double-layer photoabsorber of W / F e N i 4 ∙ 5 R G O 4 ∙ 5 (wood coated with 4.5 g L−1 of FeNi as a top layer and 4.5 g L−1 of RGO as a bottom layer) under 1 and 3 sun, respectively (1 sun = 1 kW m−2). Also, a significant reduction in the salinity (four orders of magnitude), the electrical conductivity (3000 times) and the pH (1.35 times) of the seawater was achieved after 40 min solar desalination. The ratio of produced steam rate per cost was calculated as 9 cm3 h−1 $−1 which is compared with other double-layer devices reported in the literature. In addition, W / F e N i 4 ∙ 5 R G O 4 ∙ 5 acted as an excellent sorbent for Pb (II).

To evaluate the potential of high entropy alloys for marine applications, a new high entropy alloy coating of AlCrFeNiW0.2Ti0.5 was designed and produced on Q235 steel via laser cladding. The microstructure, microhardness and tribological performances sliding against YG6 cemented carbide, GCr15 steel and Si3N4 ceramic in seawater were studied in detail. The AlCrFeNiW0.2Ti0.5 coating showed an anomalous ‘sunflower-like’ morphology and consisted of BCC and ordered B2 phases. The microhardness was approximately 692.5 HV, which was 5 times higher than substrate. The coating showed more excellent tribological performances than Q235 steel and SUS304, a typical material used in seawater environment, sliding against all three coupled balls in seawater. Besides, the wear and friction of AlCrFeNiW0.2Ti0.5 coating sliding against YG6 in seawater were most mild. The main reason was the generation of Mg(OH)2, CaCO3, metal oxides and hydroxides and the formation of protective tribo-film on the worn surface of AlCrFeNiW0.2Ti0.5 coating in the process of reciprocated sliding. This would effectively hinder the direct contact between the worn surfaces of AlCrFeNiW0.2Ti0.5 coating and YG6 ball, resulting in a decrease of friction coefficient and wear rate. Thus the YG6 was an ideal coupled material for AlCrFeNiW0.2Ti0.5 coating in seawater, and the coating would become a promising wear-resisting material in ocean environment.

Tremendous demands for highly sensitive and stable seawater salinometers have motivated intensive research on advanced electrode materials. Boron-doped diamond (BDD) is attractive in terms of its high mechanical stability and chemical inertness, but is usually hindered by its low double-layer capacitance (Cdl) for seawater salinity detection. Here, inspired by the principle of oxygen-terminated BDD electrode endowing higher Cdl than hydrogen-terminated surface, we introduce the oxygen terminated surface by oxygen plasma or reactive ion etch (RIE), and the fabricated oxygen terminated BDD electrodes demonstrate high sensitivity and long-term stability in seawater salinity detection comparing with the hydrogen terminated BDD electrodes. Significantly, the as-fabricated O-BDD-RIE electrodes not only show remarkable enhanced response even better than the commercial platinum black electrodes but also display long-time stability which is weekly verified by continuous monitor for 90 days. The outstanding performance of the oxygen terminated BDD electrodes can be ascribed to the enhancement of C-O surface functional group on Cdl. In addition, a comprehensive analysis of effective electroactive surface area (EASA) and Cdl proves that the surface oxygen is the major factor for the improved Cdl. In summary, the excellent oxygen terminated BDD electrodes promise potential application in seawater salinity detection.

International audience; The carbonate chemistry was investigated in the semiarid eutrophic Araruama Lagoon (Brazil), one of the largest hypersaline coastal lagoons in the world. Spatial surveys during winter and summer periods were performed, in addition to a diurnal sampling in summer. The hypersaline waters have higher concentrations of total alkalinity (TA) and dissolved inorganic carbon (DIC) than the seawater that feed the lagoon, due to evaporation. However, TA and DIC concentrations were lower than those expected from evaporation. Calcium carbonate (CaCO3) precipitation partially explained these deficits. The negative correlation between the partial pressure of CO2 (pCO2) and chlorophyll a (Chl a) indicated that DIC was also consumed by primary producers. The uptake by photosynthesis contributes to 57–63% of DIC deviation from evaporation, the remaining credited to CaCO3 precipitation. Marked pCO2 undersaturation was prevalent at the innermost region with shallow, confined, and phytoplankton-dominated waters, with a strong enrichment of heavier carbon isotope (δ13C-DIC up to 5.55‰), and highest pH (locally counter-acting the process of ocean acidification). Oversaturation was restricted to an urbanized region, and during night-time. The lagoon behaved as a marked CO2 sink during winter (− 15.32 to − 10.15 mmolC m−2 day−1), a moderate sink during summer (− 5.50 to − 4.67 mmolC m−2 day−1), with a net community production (NCP) of 93.7 mmolC m−2 day−1 and prevalence of net autotrophic metabolism. A decoupling between CO2 and O2 exchange rate at the air–water interface was attributed to differences in gas solubility, and high buffering capacity. The carbonate chemistry reveals simultaneous and antagonistic actions of CaCO3 precipitation and autotrophic metabolism on CO2 fluxes, and could reflect future conditions in populated and semiarid coastal ecosystems worldwide.

The abundance and distribution of dissolved Re (DRe) were determined in the freshwater part of the Krka River (Croatia), which drains a karst landscape, and in the salinity gradient of its highly stratified estuary. Due to the low DRe concentration, a batch procedure consisting of a pre-concentration step using an anion exchange resin (Dowex) and analysis of DRe in 8 M HNO3 eluate using high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) was applied. Due to potentially inconsistent recoveries, which ranged from 60 to 87%, quantification was performed using the isotope dilution technique (ID). DRe concentrations in the Krka River increased downstream, from 6.2 pM at the spring site to 11.9 pM upstream of the estuary region. Weathering of the surrounding carbonate lithology is assumed to be the source of the natural Re. Two specific anomalies were registered: a strong increase in DRe concentration due to anthropogenic input near the town of Knin (27.5 pM) and a decrease at a downstream site caused by subsurface input of freshwater from the Zrmanja River, resulting in a relatively low DRe concentration (8.5 pM). In the estuarine region, a near- conservative behavior of DRe was found in the salinity gradient of the upper surface layer, with DRe concentrations ranging from 18 to 38 pM. Anthropogenic input was suspected within the estuarine segment near the urban area, causing a small positive deviation from the conservative line. In the bottom seawater layer, a minor decrease in DRe concentration in the most upstream estuarine regions was apparent, implying weak scavenging of Re

Ice-nucleating particles (INPs) initiate the primary ice formation in clouds at temperatures above ca. −38 ∘C and have an impact on precipitation formation, cloud optical properties, and cloud persistence. Despite their roles in both weather and climate, INPs are not well characterized, especially in remote regions such as the Arctic. We present results from a ship-based campaign to the European Arctic during May to July 2017. We deployed a filter sampler and a continuous-flow diffusion chamber for offline and online INP analyses, respectively. We also investigated the ice nucleation properties of samples from different environmental compartments, i.e., the sea surface microlayer (SML), the bulk seawater (BSW), and fog water. Concentrations of INPs (NINP) in the air vary between 2 to 3 orders of magnitudes at any particular temperature and are, except for the temperatures above −10 ∘C and below −32 ∘C, lower than in midlatitudes. In these temperature ranges, INP concentrations are the same or even higher than in the midlatitudes. By heating of the filter samples to 95 ∘C for 1 h, we found a significant reduction in ice nucleation activity, i.e., indications that the INPs active at warmer temperatures are biogenic. At colder temperatures the INP population was likely dominated by mineral dust. The SML was found to be enriched in INPs compared to the BSW in almost all samples. The enrichment factor (EF) varied mostly between 1 and 10, but EFs as high as 94.97 were also observed. Filtration of the seawater samples with 0.2 µm syringe filters led to a significant reduction in ice activity, indicating the INPs are larger and/or are associated with particles larger than 0.2 µm. A closure study showed that aerosolization of SML and/or seawater alone cannot explain the observed airborne NINP unless significant enrichment of INP by a factor of 105 takes place during the transfer from the ocean surface to the atmosphere. In the fog water samples with −3.47 ∘C, we observed the highest freezing onset of any sample. A closure study connecting NINP in fog water and the ambient NINP derived from the filter samples shows good agreement of the concentrations in both compartments, which indicates that INPs in the air are likely all activated into fog droplets during fog events. In a case study, we considered a situation during which the ship was located in the marginal sea ice zone and NINP levels in air and the SML were highest in the temperature range above −10 ∘C. Chlorophyll a measurements by satellite remote sensing point towards the waters in the investigated region being biologically active. Similar slopes in the temperature spectra suggested a connection between the INP populations in the SML and the air. Air mass history had no influence on the observed airborne INP population. Therefore, we conclude that during the case study collected airborne INPs originated from a local biogenic probably marine source.

The flow of Pacific water to the North Atlantic exerts a globally significant control on nutrient balances between the two ocean basins and strongly influences biological productivity in the northwest Atlantic. Nutrient ratios of nitrate (NO3-) versus phosphate (PO43-) have previously been used to complement salinity characteristics in tracing the distribution of Pacific water in the North Atlantic. We expand on this premise and demonstrate that the fraction of Pacific water as determined by NO3- : PO43- ratios can be quantitatively predicted from the isotopic composition of sub-euphotic nitrate in the northwest Atlantic. Our linear model thus provides a critically important framework for interpreting δ15N signatures incorporated into both modern marine biomass and organic material in historical and paleoceanographic archives along the northwest Atlantic margin.

Heterogeneous reactions of NO2 on different surfaces play an important role in atmospheric NOx removal and HONO formation, having profound impacts on photochemistry in polluted urban areas. Previous studies have suggested that the NO2 uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during the daytime. However, the uptake behavior of NO2 varies with different surfaces, and different uptake coefficients were used or derived in different studies. To obtain a more holistic picture of heterogeneous NO2 uptake on different surfaces, a series of laboratory experiments using different flow tube reactors was conducted, and the NO2 uptake coefficients (γ) were determined on inorganic particles, sea water and urban grime. The results showed that heterogeneous reactions on those surfaces were generally weak in dark conditions, with the measured γ varied from

The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades. This retreat has increased the probability of the opening of the Arctic Passages in the near future. The Northwest Passage (NWP) is the most direct shipping route between the Atlantic and Pacific Oceans, producing notable economic benefits. Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988–2016, and the accessibility of the NWP was assessed under shared socioeconomic pathways (SSP245 and 585) and two vessel classes with the Arctic transportation accessibility model in 2021–2050. Sea ice thickness has decreased with increasing seawater temperature and salinity, especially within the Canadian Arctic Archipelago (CAA) in 1988–2016, which has facilitated the opening of the NWP. Complete ship navigation is projected to be possible for polar class 6 ships in August–December in 2021–2025, after when it may extends to July under SSP585 in 2026–2030, while open water ships will not be able to pass through the NWP until September in mid-21st century. The navigability of the NWP is mainly affected by the ice within the CAA. For the accessibility of the Parry Channel, the west part is worse than that of the eastern part, especially in the Viscount-Melville Sound.

Pore water data of thallium (Tl) in marine environments are scarce. It has been suggested that anoxic sediments are a sink for dissolved Tl likely due to its incorporation into Fe sulfides. However, recent studies indicated that Tl is removed from solution prior to the onset of sulfidic conditions and that Tl is involved in biological cycles in coastal seawater. To assess the Tl behavior in marine sediments, pore waters of a high energy beach (Spiekeroog Island, Germany) were sampled during different seasons and on different spatial scales. The study site provides a perfect set of samples to assess trace metal behavior under various redox conditions. Samples were analyzed for the dissolved trace metals Tl, molybdenum (Mo), uranium (U), and rhenium (Re). Additionally, sediments were incubated to monitor trace metal removal or release under controlled conditions. On-site redox conditions were characterized using dissolved oxygen (O2), manganese (Mn), and iron (Fe) concentrations. Our results indicated high enrichments of Tl in pore waters concurrently to aerobic organic matter (OM) degradation, exceeding seawater concentrations up to 6-fold. In contrast, Tl was completely removed in weakly reducing pore water characterized by more than 1 µM Mn or Fe. The spatial Tl distribution in intertidal pore waters responded to the present dissolved Mn and Fe level, which varied in space and with season. We suggest, Tl release to be attributed to OM degradation, particle desorption, or reoxidation, whereas Tl removal is likely related to the presence of trace amounts of dissolved sulfide. In conclusion, the fast reaction kinetics of Tl led to fast and complete removal in comparison to Mo, U, and Re and we suggest the following order of removal: Tl > Re > U > Mo. The removal behavior as well as the high enrichments of Tl in pore waters implicate that sinks and sources in the marine environment are not yet fully understood. Although the intertidal sediments form an overall sink for Tl (U and Re), especially under mostly anoxic conditions in summer, sediments turn into a Tl net source in winter, when sediments are more oxic. For global marine Tl balances, Tl fluxes have been estimated based on pore water Tl/Mn ratios. Contrastingly, Tl removal from pore waters at low threshold concentrations of Mn at our site indicated that these Tl flux estimations may not be applicable in permeable sandy beach sediments and in many other types of sediments, which host mildly sulfidic conditions.

Highlights • Decoupling of volatile element enrichment and magmatic volatile influx. • Multiple sulfide generations with distinct trace element signatures. • Boiling-induced pyrite precipitation revealed by textures and Tl/Pb, Sb/Pb and Bi/Pb ratios. • Boiling-induced Au, electrum and Bi-telluride colloids lead to high Au grades. • Metals sources: shallow upflow- (60–80%) and deep reaction (20–40%) zone. Abstract Shallow (30 ppm) in the mature and late stage of chimney formation. Lead isotope data indicate that the hydrothermal fluids scavenged metals not only from the deeper basement in the reaction zone (20–40%), but also from young dacitic volcanic rocks near the seafloor in the upflow zone (60–80%). Sulfur isotope (δ34S = −0.3 to 4.4‰) and Se/S*106 values (

Benzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions. A group of aromatic hydrocarbons in the remote marine atmosphere, typically classified as anthropogenic pollutants, are attributable to local biogenic sources, according to shipborne observations and mesocosm experiments.

To determine whether the marine medaka Oryzias melastigma is a suitable model organism for evaluating the effects of environmental chemicals on marine teleosts, we examined the effect of salinity on physiological development and zinc toxicity. Growth as measured by total body length was significantly lower in fresh water compared to brackish water. Reproductive success was also significantly reduced in fresh water, although we observed cells in the pituitary producing gonadotropins such as Gpa (common glycoprotein hormone α), Fshb (follicle stimulating hormone β), and Lhb (luteinizing hormone β) at all salinities. These results indicate that O. melastigma is adaptable to various salinities from fresh to seawater, and brackish water is best for physiological processes including growth performance and reproduction. When zinc was dissolved in saltwater, a white precipitate formed immediately, and the dissolved concentration decreased in the supernatant and increased at precipitate. We performed zinc toxicity tests on early life stage and adult stage in fresh water, brackish water, and seawater. Among adults, the lowest observed effect concentration for mortality in freshwater (15.3 mg/L) was lower than in brackish water (>48 mg/L) or seawater (>48 mg/L). Similarly, among embryos and larvae, the lowest observed effect concentration for mortality in freshwater (4.8 mg/L) was lower than in brackish water (48 mg/L) or seawater (48 mg/L). These results highlight the importance of using marine organisms to evaluate the ecological effects of marine pollutants.

Resistance to algae contamination is an important characteristic of insulators used in overhead power distribution in coastal environments. It is therefore important to understand the parameters governing algae adhesion onto polymer insulator materials such as silicone. Flow cell-based shear experiments were conducted in order to characterize the adhesion strength of algae onto polydimethylsiloxane surfaces, comparing fresh polymer substrates with those that have been soaked in water and saline solutions for 1 month. Both freshwater algae and seawater species could withstand considerably less drag force and were therefore more easily removed when the polymer was soaked in salt water. The polymer surface was found to be unaltered in terms of its roughness, contact angle, and lack of water uptake; no macroscopic surface characterization was therefore able to account for the differences in cell adhesion strength resulting from the soaking treatment. Surface-specific nonlinear vibrational spectroscopy, however, revealed subtle differences in the orientation of surface methyl groups that resulted from the water and saline exposure.

[Abstract] Calcified coralline algae are ecologically important in rocky habitats in the marine photic zone worldwide and there is growing concern that ocean acidification will severely impact them. Laboratory studies of these algae in simulated ocean acidification conditions have revealed wide variability in growth, photosynthesis and calcification responses, making it difficult to assess their future biodiversity, abundance and contribution to ecosystem function. Here, we apply molecular systematic tools to assess the impact of natural gradients in seawater carbonate chemistry on the biodiversity of coralline algae in the Mediterranean and the NW Pacific, link this to their evolutionary history and evaluate their potential future biodiversity and abundance. We found a decrease in the taxonomic diversity of coralline algae with increasing acidification with more than half of the species lost in high pCO2 conditions. Sporolithales is the oldest order (Lower Cretaceous) and diversified when ocean chemistry favoured low Mg calcite deposition; it is less diverse today and was the most sensitive to ocean acidification. Corallinales were also reduced in cover and diversity but several species survived at high pCO2; it is the most recent order of coralline algae and originated when ocean chemistry favoured aragonite and high Mg calcite deposition. The sharp decline in cover and thickness of coralline algal carbonate deposits at high pCO2 highlighted their lower fitness in response to ocean acidification. Reductions in CO2 emissions are needed to limit the risk of losing coralline algal diversity. Fieldwork in the Mediterranean was supported by the EU ‘Mediterranean Sea Acidification under a changing climate’ project (MedSeA; grant agreement 265103; MM, JH-S)

Photosynthetic microalgae are an attractive source of food, fuel, or nutraceuticals, but commercial production of microalgae is limited by low spatial efficiency. In the present study we developed a simple photosynthetic hydrogel system that cultivates the green microalga, Marinichlorella kaistiae KAS603, together with a novel strain of the bacteria, Erythrobacter sp. We tested the performance of the co-culture in the hydrogel using a combination of chlorophyll-a fluorimetry, microsensing, and bio-optical measurements. Our results showed that growth rates in algal–bacterial hydrogels were about threefold enhanced compared to hydrogels with algae alone. Chlorophyll-a fluorimetry–based light curves found that electron transport rates were enhanced about 20% for algal–bacterial hydrogels compared to algal hydrogels for intermediate irradiance levels. We also show that the living hydrogel is stable under different environmental conditions and when exposed to natural seawater. Our study provides a potential bio-inspired solution for problems that limit the space-efficient cultivation of microalgae for biotechnological applications.

The evolution of the global carbon and silicon cycles is thought to have contributed to the long-term stability of Earth's climate1-3. Many questions remain, however, regarding the feedback mechanisms at play, and there are limited quantitative constraints on the sources and sinks of these elements in Earth's surface environments4-12. Here we argue that the lithium-isotope record can be used to track the processes controlling the long-term carbon and silicon cycles. By analysing more than 600 shallow-water marine carbonate samples from more than 100 stratigraphic units, we construct a new carbonate-based lithium-isotope record spanning the past 3 billion years. The data suggest an increase in the carbonate lithium-isotope values over time, which we propose was driven by long-term changes in the lithium-isotopic conditions of sea water, rather than by changes in the sedimentary alterations of older samples. Using a mass-balance modelling approach, we propose that the observed trend in lithium-isotope values reflects a transition from Precambrian carbon and silicon cycles to those characteristic of the modern. We speculate that this transition was linked to a gradual shift to a biologically controlled marine silicon cycle and the evolutionary radiation of land plants13,14.

The organic mass fraction from sea spray aerosol (SSA) is currently a subject of intense research. The majority of this research is dedicated to measurements in ambient air. However a number of studies have recently started to focus on nascent sea spray aerosol. This work presents measurements collected during a 5-week cruise in May and June 2017 in the central and western Mediterranean Sea, an oligotrophic marine region with low phytoplankton biomass. Surface seawater was continuously pumped into a bubble-bursting apparatus to generate nascent sea spray aerosol. Size distributions were measured with a differential mobility particle sizer (DMPS). Chemical characterization of the submicron aerosol was performed with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) operating with 10 min time resolution and with filter-based chemical analysis on a daily basis. Using positive matrix factorization analysis, the ToF-ACSM non-refractory organic matter (OMNR) was separated into four different organic aerosol types, identified as primary OA (POANR), oxidized OA (OOANR), methanesulfonic acid type OA (MSA-OANR), and mixed OA (MOANR). In parallel, surface seawater biogeochemical properties were monitored providing information on phytoplankton cell abundance and seawater particulate organic carbon (1 h time resolution) and seawater surface microlayer (SML) dissolved organic carbon (DOC) (on a daily basis). Statistically robust correlations (for n>500) were found between MOANR and nanophytoplankton cell abundance, as well as between POANR, OOANR, and particulate organic carbon (POC). Parameterizations of the contributions of different types of organics to the submicron nascent sea spray aerosol are proposed as a function of the seawater biogeochemical properties for use in models.

Human activities are changing our environment. Along with climate change and a widespread loss of biodiversity, plastic pollution now plays a predominant role in altering ecosystems globally. Here, we review the occurrence of plastic ingestion by wildlife through evolutionary and ecological lenses and address the fundamental question of why living organisms ingest plastic. We unify evolutionary, ecological, and cognitive approaches under the evolutionary trap theory and identify three main factors that may drive plastic ingestion: (i) the availability of plastics in the environment, (ii) an individual’s acceptance threshold, and (iii) the overlap of cues given by natural foods and plastics.

To investigate isotope fractionation between biogenic carbonates and modern seawater, we measured K concentration, phase, and isotopic composition in calcified skeletons from a variety of calcifying species. Samples included deep-sea corals, hermatypic corals, bivalves, gastropods, brachiopods, and planktonic foraminifera recovered globally over the past ten years in habitats with temperatures varying from 2 to 29 °C. The δ41K values of the calcified organisms vary significantly, ranging from −0.72 ± 0.11 to 0.94 ± 0.04‰. Deep-sea corals exhibit the largest isotopic variability and the lowest δ41K, ranging from −0.72 ± 0.11 to 0.28 ± 0.09‰. Hermatypic corals display a moderate δ41K, ranging from −0.20 ± 0.07 to 0.37 ± 0.10‰. Bivalves display widely variable δ41K values from 0.04 ± 0.05 to 0.94 ± 0.04‰, including the highest δ41K observed. Gastropods exhibit δ41K values between −0.42 ± 0.06 and −0.12 ± 0.06‰, while brachiopods have δ41K values from −0.30 ± 0.05 to 0.24 ± 0.06‰. Limited foraminifera samples (n = 2) reveal δ41K values of 0.15 ± 0.06 to 0.21 ± 0.06‰. Synchrotron-based atomic analyses show that K in biogenic carbonates is dominantly hosted in amorphous K2CO3, calcite-like and aragonite-like K phases, and intracrystalline organic matrices of varying proportions. The K isotopic composition of marine biogenic carbonates is not strongly temperature-dependent, in general, but correlates with skeletal K phases. This phase-control may indicate a first-order biological control on skeletal K incorporation, partitioning, and associated K isotope fractionation. This appears to reflect a substantial “vital effect”; i.e., physiological modification of the environmental information recorded in calcifying organisms. Substantial variations in δ41K call for additional scrutiny before using marine biogenic carbonates to interpret ancient seawater δ41K composition as physiological modulation substantially complicates the interpretation of marine carbonate δ41K records through time. Future studies should include species-specific calibration with complementary synchrotron data to refine K isotope applications for paleoceanography.

The demersal brown banded bamboo shark Chiloscyllium punctatum is a major component of sharks landed in Malaysia. However, little is known about their population structure and the effect of high fishing pressure on these weak swimming sharks. Both mitochondrial DNA control region (1072 bp) and NADH dehydrogenase subunit 2 (1044 bp) were used to elucidate the genetic structure and connectivity of C. punctatum among five major areas within the Sundaland region. Our findings revealed (i) strong genetic structure with little present day mixing between the major areas, (ii) high intra-population genetic diversity with unique haplotypes, (iii) significant correlation between genetic differentiation and geographical distance coupled with detectable presence of fine scale geographical barriers (i.e. the South China Sea), (iv) historical directional gene flow from the east coast of Peninsular Malaysia towards the west coast and Borneo, and (v) no detectable genetic differentiation along the coastline of east Peninsular Malaysia. Genetic patterns inferred from the mitochondrial DNA loci were consistent with the strong coastal shelf association in this species, the presence of contemporary barriers shaped by benthic features, and limited current-driven egg dispersal. Fine scale population structure of C. punctatum highlights the need to improve genetic understanding for fishery management and conservation of other small-sized sharks.

This study aims to develop efficient desalination equipment that increases the distilled water production rate and enhances heat transfer in the evaporator. It focuses on the impact of equipment geometry and energy storage during the daytime and nocturnal period. In addition, the effects of the energy storage system, which is placed in two specific areas on the yield of the distillation process with and without energy storage, have been studied. The heat exchanger system provides the energy to the water to be treated in the daytime, while the concrete part provides the energy storage in the desalination evaporator at night time. The experimental test results showed that the increase of distilled water through the heating system is very important in comparison to the productivity of the conventional solar still. The obtained results indicate that the use of energy storage increases productivity by 50% in the nocturnal period. Indeed, the daily productivity of the concrete solar still, strongly affected by the heat transfer produced via concrete to the water evaporator, is presented in this study. It was found that the average daily distillate output of concrete solar still with energy storage is more significant than that of a solar still without energy storage. HIGHLIGHTS Design and realization of a new solar still coupled with flat plate solar collector experimented under climatic conditions of the Bou-Ismail region.; Integration of an energy storage system.; Acceleration of water preheating.; Increased operating time of the still after sunset.; System performance improvement.

In June 2009, the Intergovernmental Oceanographic Commission of UNESCO released The international thermodynamic equation of seawater – 2010 (TEOS-10 for short; IOC et al., 2010) to define, describe and calculate the thermodynamic properties of seawater. Compared to the Equation of State-1980 (EOS-80 for short), the most obvious change with TEOS-10 is the use of Absolute Salinity as salinity argument, replacing the Practical Salinity used in the oceanographic community for 30 years. Due to the lack of observational data, the applicability of the potentially increased accuracy in Absolute Salinity algorithms for coastal and semi-enclosed seas is not very clear to date. Here, we discuss the magnitude, distribution characteristics, and formation mechanism of Absolute Salinity and Absolute Salinity Anomaly in Chinese shelf waters, based on the Marine Integrated Investigation and Evaluation Project of the China Sea and other relevant data. The Absolute Salinity SA ranges from 0.1 to 34.66 g kg−1. Instead of silicate, the main composition anomaly in the open sea, CaCO3 originating from terrestrial input and re-dissolution of shelf sediment is most likely the main composition anomaly relative to SSW and the primary contributor to the Absolute Salinity Anomaly δSA. Finally, relevant suggestions are proposed for the accurate measurement and expression of Absolute Salinity of the China offshore waters.