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The behavior of suspended particles in turbulent flows is a recalcitrant problem spanning wide‐ranging fields including geomorphology, hydrology, and dispersion of particulate matter in the atmosphere. One key mechanism underlying particle suspension is the difference between particle settling velocity (ws) in turbulence and its still water counterpart (wso). This difference is explored here for a range of particle‐to‐fluid densities (1–10) and particle diameter to Kolmogorov micro‐eddy sizes (0.1–10). Conventional models of particle fluxes that equate ws to wso result in eddy diffusivities and turbulent Schmidt numbers contradictory to laboratory experiments. Incorporating virtual mass and Basset history forces resolves these inconsistencies, providing clarity as to why ws/wso is sub‐unity for the aforementioned conditions. The proposed formulation can be imminently used to model particle settling in turbulence, especially when sediment distribution outcomes over extended time scales far surpassing turbulence time scales are sought. Plain Language Summary: In rivers and streams, mixed‐up dirt called "suspended sediments" is known to influence water quality and its concomitant effects on many physical, chemical, and biological processes. Suspended sediments can be harmful to aquatic ecosystem productivity because they reduce light penetration. They can clog gills of fish and other aquatic organism, and they can impact reservoir operation and their capacity necessitating frequent dredging. There is debate about how these sediments interact with swirling motions ("turbulent flows") in moving water. Traditional mathematical models overlook how individual grains are affected by these swirls ("turbulent eddies") and how they displace water ("virtual mass") when sediments move in a fluid. For large grains, these overlooked details can generate new terms in the force balance that are associated with complex eddying motion lagging behind the grain motion ("Basset history term"). Including the Basset history and virtual mass factors reconciles controversies between recent laboratory experiments and traditional theories about how grains settle in turbulent flows. Key Points: Settling velocity of suspended sediments is reduced by virtual mass and Basset history for grains larger than turbulent micro‐scalesAn operational Rouse‐like budget that models these two effects is derived and tested against experimentsTurbulent Schmidt number exceeding unity in the experiments can be linked to these two effects [ABSTRACT FROM AUTHOR]

Marine sediments comprise the primary long‐term sink of organic matter (OM) in marine systems. Disentangling the diverse origins of OM and the influence of the main processes that determine organic carbon (OC) fate at a global scale has proven difficult due to limited spatial data coverage. Thus, comprehensive studies of the spatial distribution of the content and geochemical characteristics of sedimentary OM at basin scales provide fundamental knowledge on the role of marine sediments in the global carbon cycle. Here, we shed light on the origin of OM and the underlying mechanisms that determine its fate in a semi‐enclosed basin by examining the spatial patterns in the isotopic and elemental composition of OM in 149 core‐top samples from the Western Mediterranean Sea and the adjacent Atlantic Ocean sector. Our results reveal an apparent SW‐NE gradient that reverses in the Gulf of Lions in most geochemical and sedimentological features. Changes in the OC content and ẟ13C and Δ14C signatures are ascribed to spatial variations in marine primary productivity and the influence of varying discharge of rivers and well‐developed canyons that favor the cross‐shelf transport of terrestrial (and petrogenic) OC. Our results also suggest the potential influence of two other mechanisms on the geochemical signatures of OM: (a) lateral transport of allochthonous OC and selective degradation of labile OM, which potentially occurs across the studied area having a greater impact toward the north‐eastern region, and (b) OM protection via association with mineral surfaces, potentially having a greater influence toward the south‐western basins. Key Points: Geochemical and sedimentological signals depict a clear SW‐NE gradient that reverses in the Gulf of LionsThis gradient is mainly attributed to differences in local primary productivity and delivery of terrestrial organic carbonOrganic matter protection by mineral surfaces and lateral transport are proposed as potential additional controls [ABSTRACT FROM AUTHOR]

We utilized the 228Th/228Ra and 234Th/238U disequilibrium methods to estimate the export of particulate organic carbon (POC) from the upper twilight zone in the northern South China Sea during four cruises from August 2009 to May 2011, covering an entire seasonal cycle of spring, summer, autumn, and winter. A significant finding of this study is that 228Th/228Ra disequilibrium method is highly sensitive for tracing POC export in the twilight zone, as demonstrated by the comparison of the "Minimum Detection Limit" (MDL) of various methods. We thus further conclude that 228Th/228Ra disequilibrium is suitable for the research of the twilight zone by comparing the POC export fluxes derived from 228Th/228Ra and 228Ra‐NO3− disequilibrium. The mesopelagic transfer efficiency (Teff), defined as the ratio of POC flux at 500–100 m, varied from 8% to 130%. The Teff derived from >53 μm 234Th (228Th) was higher than that based on 1–53 μm. Large particles were observed to sink rapidly and exit the twilight zone. The Teff was lower at the sampling station influenced by the Kuroshio waters in winter and spring, where the exported organic matter was relatively labile and prone to remineralization in the twilight zone. Conversely, the Teff was relatively higher at other stations, indicating that the exported organic matter was refractory and underwent comparatively less degradation in the twilight zone. Key Points: The mesopelagic transfer efficiency (Teff) was determined to be 8%–130%228Th/228Ra disequilibrium is an extremely sensitive method for tracing particulate organic carbon (POC) export in the twilight zonePOC export fluxes above 500 m derived from 234Th/238U and 228Th/228Ra disequilibria were inconsistent due to the different time scales [ABSTRACT FROM AUTHOR]

The twenty‐first century is confronted with the consequences of enormous amounts of global emerging plastic waste resulting from an excessive use of plastic, which has been imparting several negative impacts on the environment and human health. Moreover, some novel variants have also been reported in some coastal environments, so far, as a result of mixing of plastic waste with various other matrices. As a result, the problem of various forms of plastic waste within the marine ecosystem has emerged as a major concern in recent years. The current review is focused on the detrimental implications of various emerging and novel plastic variants, with an emphasis on coastal and marine environments. This review highlights the fate and transportation patterns of plastic waste, along with the contemporary examples of its implications on marine biota. Additionally, this work also examines the impacts of marine plastic waste on the environment. The review further highlights the importance of circular economy of plastic waste for sustainability. Then in the end, the growing anxieties about the impacts of plastic waste on coastal as well as marine environment, along with the strategies for reducing its impacts on ecological sustainability are discussed. This article is categorized under: Climate and Environment > Circular Economy [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are frequently regarded as environmental and biota contaminants. Yet, research on the accumulation of MPs in living entities, particularly aquatic insects that serve as food resources in the aquatic food chain, is limited. This study to investigate the accumulation of MPs in aquatic insects from water and sediment in an Egyptian wastewater basin. Four typical freshwater insect groups were used. The highest MP load per gram wet weight was reported by collector‐gatherers (Chironomus sp. and Hydrophilus sp.), followed by collector‐filterers (Culex sp.) with the second highest MP load. However, Predators (Aeshna sp.) had the lowest values. Also, the present results showed a reduction in the number of MPs in all insect taxa tested after a 24 h depuration time, with differences in the observed egestion ability. The mean number of MPs per individual significantly reduced after 24 h in both Chironomus sp. and Culex sp. larvae, where 53% and 40% of MPs particles were ejected from them, respectively. However, the ability of MP egestion decreases in Aeshna sp. nymph (25%), and the lowest proportion of ejection was observed in Hydrophilus sp. adults (9%). Polyethylene terephthalate fibers were the most abundant type of MP in both sediment and water, followed by fragments (polyethylene and polypropylene). Yet, only polyester fibers were detected in the various insect species. The average length of fibers in the various insects was somewhat shorter than in the surrounding environment. The current study reveals that MP ingestion by aquatic insects is not always related to levels of pollution in the environment, since other factors such as feeding strategies may play a role in MP ingestion. Based on these observations, further studies should be carried out on studies on toxicological impacts of MPs on freshwater/aquatic biota. [ABSTRACT FROM AUTHOR]

Active continental margins are tectonic sites with complex sedimentary processes. Tectono–sedimentary interactions occur over geological time and determine the modern morphology of the margin. However, such interactions have been poorly documented in high‐latitude regions. This study focuses on deep‐water sedimentary systems on the South Shetland convergent margin, which is the only remaining active continental margin in Antarctica. Numerous gullies, 20 canyons and three contourite drifts are identified by interpreting bathymetry, oceanography and reflection seismic data. Heavy mineral contents of a gravity core, located at a downslope elongated mounded drift, show the asynchronous interplay of downslope and alongslope processes. The rest of the margin is dominated by turbidity currents. Variations in the slope gradient control thalweg profiles and sinuosity of canyons. Tectonic‐related morphology restricts the distribution of contourite drifts. Earthquakes triggered by underplating and tectonic compression may induce slope instability at the lower flank of the plastered drift. Tectonic uplift influences the amount of sediments transported by ice sheets and controls the shelf stacking pattern. The mixed turbidite–contourite system transitions to separated canyon and drift systems from passive to active continental margins under the influence of the tectonic‐related morphology. A systematic comparison has been made among several convergent margins with similar tectonic settings. Results suggest that submarine canyons on these shelf‐slope systems have similar morphological features and are comparable in size. Coarse sediment input and steep continental slopes (mean slope 7 to 10°) control the canyon morphology on these margins. Therefore, this research has important implications for furthering the current understanding of sedimentary systems on high‐latitude convergent margins and tectono–sedimentary interactions. [ABSTRACT FROM AUTHOR]

Outcrops of coarse‐grained, high‐angle clinoform sets are mainly thought to represent Gilbert‐type deltas. Superficially similar clinoform sets may, however, form in marine, sub‐wave base settings. They are interpreted to have formed as a result of storms where downwelling, seaward‐directed currents transported sand from the coastal area and shoreface across the shelf in suspension or as bedload to be deposited as clinothems. An additional transport of sand took place by strong coast‐parallel currents. The clinoform sets appear to be associated with rift events, the creation of accommodation space and an increasing supply of coarse‐grained sediment. A major protracted rift phase was initiated in East Greenland in Middle Jurassic times and intensified through the Late Jurassic to reach a climax close to the Jurassic–Cretaceous boundary. Rifting caused uplift of borderlands, creation of accommodation space and development of shallow marine shelves passing offshore into submarine slopes and deeper basinal areas. Each rift event was accompanied by the formation of clinoform sets prograding seawards towards the east and southeast away from the cratonic coastline in water depths below the wave base. The clinoform sets are interpreted as typical motifs for rift events in the relatively shallow epeiric Jurassic seaway between East Greenland and Norway. Outcrops of such sets represent a little‐known, commonly misinterpreted sedimentary system and may serve as motifs for rifting in shallow marine areas elsewhere in the geological record. Similar sets have been recorded in outcrop from the Mediterranean, and elsewhere and are probably more common than hitherto realized. [ABSTRACT FROM AUTHOR]

In legal scholarship, as in other fields, it would seem that 'choice‐architecture' (where states attempt to 'move' people toward desired behaviour) is everywhere. This paper argues that such blanket adoption of choice‐architecture discourse cannot be based on generic terms, nor on imagined or assumed choices. Rather, I contend, the specific characteristics of each legal field – here, poverty law – should be considered when debating and reviewing choice‐architecture. I point to the dangers of using choice‐discourse in the context of poverty law, illuminate significant weaknesses in choice‐architecture theory, and thus justify limitations on the use of incentives and nudges in this context. I propel the poverty‐as‐exception argument, advancing the development of poverty law toward being considered a distinct field of law. The contributions of this paper are thus both theoretical and normative, shifting focus onto those exposed to choice‐architecture, and to the expressive harms caused by assuming choice where there is none. [ABSTRACT FROM AUTHOR]

Microplastics are a globally pervasive pollutant with the potential to directly impact species and accumulate in ecosystems. However, there remains a relative paucity of research addressing their accumulation in freshwater ecosystems and a near absence of work in crayfish, despite their high ecological and economic importance. This study investigated the presence of microplastics in the invasive signal crayfish Pacifastacus leniusculus along a stream urbanization gradient. The results demonstrate a ubiquitous presence of microplastics in crayfish digestive tracts at all sites and provide the first evidence of microplastic accumulation in tail tissue. Evidence of a positive linear trend was demonstrated between microplastic concentration in crayfish and upstream urban area size in generalized linear models. Evidence for a positive effect of the upstream urban area and a negative effect of crayfish length on microplastic concentrations in crayfish was demonstrated in multiple generalized linear regression models. Our results extend the current understanding of microplastics presence in freshwater ecosystems and demonstrate their presence in crayfish in the wild for the first time. [ABSTRACT FROM AUTHOR]

Microplastic (MP) pollution is one of the greatest threats to marine ecosystems. Cold seeps are characterized by methane‐rich fluid seepage fueling one of the richest ecosystems on the seafloor, and there are approximately more than 900 cold seeps globally. While the long‐term evolution of MPs in cold seeps remains unclear. Here, how MPs have been deposited in the Haima cold seep since the invention of plastics is demonstrated. It is found that the burial rates of MPs in the non‐seepage areas significantly increased since the massive global use of plastics in the 1930s, nevertheless, the burial rates and abundance of MPs in the methane seepage areas are much lower than the non‐seepage area of the cold seep, suggesting the degradation potential of MPs in cold seeps. More MP‐degrading microorganism populations and functional genes are discovered in methane seepage areas to support this discovery. It is further investigated that the upwelling fluid seepage facilitated the fragmentation and degradation behaviors of MPs. Risk assessment indicated that long‐term transport and transformation of MPs in the deeper sediments can reduce the potential environmental and ecological risks. The findings illuminated the need to determine fundamental strategies for sustainable marine plastic pollution mitigation in the natural deep‐sea environments. [ABSTRACT FROM AUTHOR]

Abiotic environmental conditions can significantly influence the way species interact. In particular, plant–herbivore interactions can be substantially dependent on temperature and nutrients. The overall product of these relationships is critical for the fate and stability of vegetated ecosystems like marine forests. The last few decades have seen a rapid spread of barrens on temperate rocky reefs mainly as a result of overgrazing. The ecological feedbacks that characterize the barren state involve a different set of interactions than those occurring in vegetated habitats. Reversing these trends requires a proper understanding of the novel feedbacks and the conditions under which they operate. Here, we explored the role of a secondary herbivore in reinforcing the stability of barrens formed by sea urchin overgrazing under different nutrient conditions. Combining comparative and experimental studies in two Mediterranean regions characterized by contrasting nutrient conditions, we assessed: (i) if the creation of barren areas enhances limpet abundance, (ii) the size‐specific grazing impact by limpets, and (iii) the ability of limpets alone to maintain barrens. Our results show that urchin overgrazing enhanced limpet abundance. The effects of limpet grazing varied with nutrient conditions, being up to five times more intense under oligotrophic conditions. Limpets were able to maintain barrens in the absence of sea urchins only under low‐nutrient conditions, enhancing the stability of the depauperate state. Overall, our study suggests a greater vulnerability of subtidal forests in oligotrophic regions of the Mediterranean and demonstrates the importance of environment conditions in regulating feedbacks mediated by plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

As the levels of plastic use in global society have increased, it has become crucial to regulate plastics of all sizes including both microplastics (MPs) and nanoplastics (NPs). Here, the published literature on the current laws passed by the US Congress and regulations developed by various federal agencies such as the US Environmental Protection Agency and the US Food and Drug Administration (FDA) that could be used to regulate MPs and NPs have been reviewed and analyzed. Statutes such as the Clean Water Act, the Safe Drinking Water Act, the Toxic Substances Control Act (TSCA), the Resource Conservation and Recovery Act, and the Clean Air Act can all be used to address plastic pollution. These statutes have not been invoked for MP and NP waste in water or air. The Federal Food, Drug, and Cosmetic Act provides guidance on how the FDA should evaluate plastics use in food, food packaging, cosmetics, drug packaging, and medical devices. The FDA has recommended that acceptable levels of ingestible contaminant from recycled plastic are less than 1.5 µg/person/day, which is 476 000 times less than the possible ingested daily dose. Plastic regulation is present at the state level. States have banned plastic bags, and several cities have banned plastic straws. California is the only state beginning to focus on monitoring MPs in drinking water. The future of MP regulation in the USA should use TSCA to test the safety of plastics. The other statutes need to include MPs in their definitions. For the FDA, MPs should be redefined as contaminants—allowing tolerances to be set for MPs in food and beverages. Through minor changes in how MPs are classified, it is possible to begin to use the current statutes to understand and begin to minimize the possible effects of MPs on human health and the environment. Integr Environ Assess Manag 2023;19:474–488. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: Microplastics (MPs) and nanoplastics (NPs) are largely absent from regulatory statutes.The typical American ingests 467 000 times the recommended acceptable daily dose of recycled plastic.Both the science of MP and NP research and regulatory policies must be addressed to solve the plastic crisis.By redefining MPs as toxic or contaminants, these particles can use the existing statutes for regulatory purposes. [ABSTRACT FROM AUTHOR]

Microplastic categorization schemes are diverse, thereby posing challenges for cross‐study comparisons. Further, categorization schemes are not necessarily aligned with and, thus, useful for applications such as source reduction initiatives. To address these challenges, we propose a hierarchical categorization approach that is "fit for purpose" to enable the use of a scheme that is tailored to the study's purpose and contains categories, which, if adopted, would facilitate interstudy comparison. The hierarchical categorization scheme is flexible to support various study purposes (e.g., to support regulation and toxicity assessment) and it aims to improve the consistency and comparability of microplastics categorization. Categorization is primarily based on morphology, supplemented by other identification methods as needed (e.g., spectroscopy). The use of the scheme was illustrated through a literature review aimed at critically evaluating the categories used for reporting microplastic morphologies in North American freshwater environments. Categorization and grouping schemes for microplastic particles were highly variable, with up to 19 different categories used across 68 studies, and nomenclature was inconsistent across particle morphologies. Our review demonstrates the necessity for a "fit for purpose" categorization scheme to guide the information needs of scientists and decision‐makers for various research and regulatory objectives across global, regional, and local scales. Integr Environ Assess Manag 2023;19:422–435. © 2022 SETAC Key Points: A fit‐for‐purpose, hierarchical categorization scheme based primarily on morphology is proposed to address diverse research objectives while facilitating consistent and comparable microplastic categorization.The value of the scheme is illustrated through a literature review aimed at critically evaluating the categories used for reporting microplastic morphologies in North American freshwater environments. [ABSTRACT FROM AUTHOR]

Export of sinking particles from the surface ocean is critical for carbon sequestration and to provide energy to the deep biosphere. The magnitude and spatial patterns of this export have been estimated in the past by in situ particle flux observations, satellite‐based algorithms, and ocean biogeochemical models; however, these estimates remain uncertain. Here, we use a recent machine learning reconstruction of global ocean particle size distributions (PSDs) from Underwater Vision Profiler 5 measurements to estimate carbon fluxes by sinking particles (35 μm–5 mm equivalent spherical diameter) from the surface ocean. We combine global maps of PSD properties with empirical relationships constrained against in situ flux observations to calculate particulate carbon export from the euphotic zone (5.8 ± 0.1 Pg C y−1) and annual maximum mixed layer depths (6.1 ± 0.1 Pg C y−1). The new flux reconstructions suggest a less variable seasonal cycle in the tropical ocean and a more persistent export in the Southern Ocean than previously recognized. Smaller particles (less than 418 μm) contribute most of the flux globally, while larger particles become more important at high latitudes and in tropical upwelling regions. Export from the annual maximum mixed layer exceeds that from the euphotic zone over most of the low‐latitude ocean, suggesting shallow particle recycling and net heterotrophy in the deep euphotic zone. These estimates open the way to fully three‐dimensional global reconstructions of particle fluxes in the ocean, supported by the growing database of in situ optical observations. Key Points: A new estimate of sinking particulate carbon fluxes from the surface ocean is developed from reconstructions of particle size distributionSmaller particles contribute more to the total sinking carbon flux than large particlesCarbon flux estimates from two depth horizons suggest net heterotrophy in the deeper euphotic zone, rather than autotrophy [ABSTRACT FROM AUTHOR]

CaCO3 is an important component of marine sediments and one of the major deep‐carbon carriers at subduction zones. Some subducted CaCO3 can be dissolved in subduction fluids and recycled back to the surface via arc volcanoes degassing. At the same time, there still remain large amounts of CaCO3 and its reaction products, which could be further transported into Earth's deep interior. These internal processes link atmosphere, hydrosphere and biosphere with the deep solid Earth, modifying the environments of our planet. In this review, we summarize current understanding from high pressure‐temperature experiments and field petrological observations on the physical and chemical properties of CaCO3. In particular, the phase stability and reactions of CaCO3 largely control the migration and reservation of oxidized carbon in subducting slabs. Finally, we present several critical but unsolved questions on CaCO3 subducting in the deep mantle. [ABSTRACT FROM AUTHOR]

Storfjorden, Svalbard, hosts a polynya in winter and is an important source region of Brine‐enriched Shelf Water (BSW) that, if dense enough, feeds the Arctic Ocean deep water reservoir. Changes in the BSW production may thus have far‐reaching impacts. We analyze the water mass distribution and circulation in Storfjorden and the trough south of it, Storfjordrenna, using hydrographic sections occupied in July 2016, following a winter characterized by the lowest ice coverage recorded in the Barents Sea. These observations reveal an unusual hydrographic state, characterized at the surface by the near absence of Melt Water and Storfjorden Surface Water, replaced by a saltier water mass. At depth, BSW (maximum salinity of 34.95) was found from the bottom up to 90 m, above the 120‐m deep sill at the mouth to Storfjordrenna. However, no gravity driven overflow was observed downstream of the sill: the dome of BSW remained locked over the depression in a cyclonic circulation pattern consistent with a stratified Taylor column. Observations further reveal a previously unreported intrusion of Atlantic Water (AW) far into the fjord, promoting isopycnal mixing with entrapped Arctic Water. This intrusion was possibly favored by positive wind stress curl anomalies over Svalbardbanken and Storfjordrenna. The bottom plume exiting Storfjordrenna was weak, carrying Polar Front Water rather than BSW, too light to sink underneath the AW layer at Fram Strait. Whether Storfjorden switched durably to a new hydrographic state, following the observed Atlantification of the Barents Sea after 2005, remains to be established. Plain Language Summary: Storfjorden, east of Spitsbergen, plays an important role in Arctic Ocean climate through formation of dense water as salt is added to the ocean when sea ice forms. This dense water accumulates in winter before spilling toward the deep ocean into autumn, fueling the global ocean's circulation. We analyze observations from a research cruise in July 2016, following a winter season characterized by the lowest ice coverage in the Barents Sea ever recorded. These observations reveal striking differences from previous reports, which are mostly based on data prior to the 2005 regime shift in the Barents Sea characterized by warmer temperature and reduced ice cover, an expression of its "Atlantification" reported by many authors. First, the expected overflow of the locally formed dense water was absent. The latter, less saline than usual, was instead trapped in Storfjorden suggesting an intermittent discharge regime usually observed in the fall. Another notable observation is the intrusion of Atlantic Water far inside the fjord. Such a flooding episode, increasingly frequent in the fjords of the west coast of Spitsbergen, is previously unreported in Storfjorden. These observations made in the wake of an exceptionally mild winter could prefigure more permanent changes in this important region. Key Points: Changes in the hydrography and circulation in Storfjorden a decade after a regime shift in the Barents Sea linked to its AtlantificationThe less saline Brine‐enriched Shelf Water remained entrapped in Storfjorden within a cyclonic circulation pattern with no overflowStorfjorden was flooded with Atlantic Water, promoting isopycnal mixing with Arctic Water and the local formation of East Spitsbergen Water [ABSTRACT FROM AUTHOR]

We present a 1-yr (2005-2006) record of organic carbon (OC) and total nitrogen (TN) contents and their isotopic ratios (δ13COC and δ 15N) in sinking particles from the western Gulf of Lions. Maximum OC and TN fluxes recorded in January 2006 and March-April 2006 were associated with negative near-bottom temperature anomalies. This reveals large inputs of resuspended organic matter from the shelf basinwards to depths >1500 m by dense shelf-water cascading. The first pulse of organic matter had low δ13COC (-25.5‰) and N:C (0.08) and high δ15N (6.6‰) values, indicative of the arrival of organic matter of terrestrial origin. In contrast, the second pulse had high δ13COC (-21.9‰) and N:C (0.15) and extremely low δ15N (0.0‰) values, indicative of the transfer of organic matter with higher marine contribution. Though downslope export of organic matter from the adjacent shelf predominated, particles escaping from surface waters remained an important source of organic matter during low-energy and low-flux periods and especially during summer conditions, with significant contribution of N2 fixation to organic matter export. Overall, our results suggest the export of organic matter from different sources to the deep Mediterranean basin, which in turn might alter within a couple of months the quality of the sedimentary organic matter deposited on the sea floor and thus the dynamics of the deep ecosystems. [ABSTRACT FROM AUTHOR]

Cash management is important for energy SMEs, which, differently from large firms, face severe financial constraints and need to seize growth opportunities to ensure their survival. This paper, analyzing a large sample of European energy SMEs, finds a positive effect of holding a buffer of cash on firm performance. It shows that a stock of cash allows energy firms to prevent negative contingencies and/or achieve valuable growth patterns and investments. Moreover, considering that the energy industry is involved in environmental sustainability policies promoted by national governments, we find that complying with environmental regulations reduces the value of cash. Countries that pay more attention to environmental issues provide energy SMEs with growth opportunities and financial support, reducing the need to hold a stock of cash. A key implication is that, in a context with high environmental concern, energy SMEs have more financial flexibility to guarantee their growth with positive externalities for the energy sector. [ABSTRACT FROM AUTHOR]

210Bi (t1/2 = 5.01 d) is theoretically a radionuclide for tracing the particle cycle over a timescale of hours to days. However, it has been rarely investigated in marine environments due to its very short half‐life and low activity. Here, 210Bi and 210Pb were examined in the water column on the shelf/slope of the northern South China Sea (SCS), as well as their atmospheric deposition. In rainwater, the 210Bi/210Pb ratio averaged 0.54 ± 0.28, indicating the influence of atmospheric deposition on the disequilibrium between 210Bi and 210Pb in surface seawater. On the shelf, 210Bi/210Pb averaged 0.73 ± 0.10 in the euphotic zone and 1.25 ± 0.10 below, supporting a quick removal of 210Bi from the euphotic zone and regeneration in the twilight zone. On the slope, deficits in 210Bi (210Bi/210Pb of 0.81 ± 0.07) were also observed in the productive low euphotic zone. The concurrence of 210Bi deficits and higher particulate organic carbon (POC) concentrations implied that POC largely dominates the deficit and excess of 210Bi. Based on a simple model, the removal fluxes of 210Bi at the euphotic base were 728 ± 73 dpm m−2 d−1 and 216 ± 89 dpm m−2 d−1 on the shelf and slope. The residence time of particulate 210Bi was 14 ± 2 d. The 210Bi‐derived export flux of POC was 1.7 ± 0.7 mmol‐C m−2 d−1 out of the euphotic zone over the slope. These results lay the foundation for 210Bi/210Pb to quantify the sinking and remineralization of particulate organic matter in coastal seas. Key Points: For the first time, vertical profiles of 210Bi were examined in natural seawaterDeficit 210Bi in the euphotic zone and excess 210Bi in the upper twilight zone were observed210Bi‐210Pb is a new tracer of particle dynamics on a short timescale in the sea [ABSTRACT FROM AUTHOR]

Ruppia cirrhosa (Ruppia) seed layers have been used to constrain the age of footprints along the eastern shoreline of Paleolake Otero in southern New Mexico to around 21,000–23,000 calibrated years before the present. However, there remain two unresolved questions that can affect the reliability of the age(s) of the footprints. First, what is the nature of the geological context of the seed layers? Second, did the hard‐water effect impact the accuracy of the radiocarbon dates? It has been argued that the dated Ruppia plants grew in situ in a very shallow, freshwater‐infused system that minimized the hard‐water effect. Many of these Ruppia seed layers contain ball‐like aggregations made of Ruppia plant materials. We provide new evidence that these balls and seed layers were introduced to the discovery site by high wind seiche events during Late Pleistocene thunderstorms. In our proposed site formation model, the Ruppia plants and seeds originated in deeper water settings outside the site, thus it is very likely that the hard‐water effect has impacted the accuracy of the radiocarbon dates. As such, the radiocarbon assays of Ruppia seeds previously used to date the prehistoric footprints along Paleolake Otero could be thousands of years too old. [ABSTRACT FROM AUTHOR]

The vertical distribution of species richness, abundance and biomass of planktonic ostracods down to a depth of 1000 m were studied in the northeastern South China Sea (NESCS) during March and in the central South China Sea (CTSCS) during September 2016. A total of 47 species of halocyprids were identified, with 46 species recorded in the NESCS and 28 species in the CTSCS. Most of the species observed were concentrated in the mesopelagic zone (200–1000 m), but the majority of species abundance and biomass occurred in the 25 m to 300 m water column. Results of statistical analysis showed that the vertical distribution of planktonic ostracods was associated with chlorophyll a concentration and sampling depth. The high abundance and species richness of ostracods in the NESCS were probably influenced by the Kuroshio intrusion and eddies leading to high levels of chlorophyll a concentration. The biomass of large‐sized individuals with low abundance is equal to or larger than, the extremely small‐sized individuals with high abundance, particularly in deep layers. The body sizes of planktonic ostracods were found to increase from surface to deeper water layers, indicating a trend of greater body length and higher biomass of ostracods in deep sea. [ABSTRACT FROM AUTHOR]

Community‐based participatory research (CBPR) approaches to promoting justice focus on working from the ground up and giving a voice to marginalized communities regarding their concerns, potential solutions, and how to address social justice issues that matter to them. The pursuit of justice is often related to efforts to attain personal as well as collective well‐being. In this paper, we illustrate three exemplars of community psychologists' efforts to promote justice. Within each case study, we discuss the social and community context and examine how the researchers built partnerships and solidarity, developed ways of doing, and approached challenges and solutions. First, we present an example to promote economic justice through an entrepreneurship initiative developed in collaboration with young Black youth with disabilities in the United States. The second case illustrates an effort to promote reproductive justice in collaboration with Roma women and girls in Spain. The third exemplar depicts the use of life stories as a method to raise the voices of displaced, marginalized indigenous women in Peru. Based on these three case studies, we present a synthesis model of social justice. We also discuss implications for future studies emphasizing the importance of engaging community participants in research meaningful ways, developing sustainable partnerships, and decolonizing research. Highlights: Promoting justice requires ongoing reflective dialogue and deconstruction of a colonial approach.Acting on power imbalances, giving voice to people, and advocating for change promote social justice.Community‐based participatory research is the appropriate approach to elevate the voices of those affected by oppression. [ABSTRACT FROM AUTHOR]

Deep‐sea mineral extraction is a fledgling industry whose guiding principles, legislation, protocols, and regulations are still evolving. Responsible management of the industry is difficult when it is not clearly understood what biological and environmental diversity or ecosystem services may be at risk. But the industry's infancy provides an opportunity to address this challenge by stakeholder‐led development and implementation of a multidisciplinary risk assessment framework. This article aims to present the findings of a workshop held in New Zealand that hosted stakeholders from a broad range of interests and regions in the South Pacific associated with the deep‐sea mineral activity. The outputs provide stakeholder‐informed ecological risk assessment approaches for deep‐sea mining activities, identifying tools and techniques to improve the relevance of risk assessment of deep seabed mining projects to communities in the South Pacific. Discussions highlighted the importance of trust or respect among stakeholders, valuing the "life force" of the ocean, the importance of scientific data, and the complications associated with defining acceptable change. This research highlighted the need for a holistic transdisciplinary approach that connects science, management, industry, and community, an approach most likely to provide a "social license" to operate. There is also a need to revise traditional risk assessment methods to make them more relevant to stakeholders. The development of ecotoxicological tools and approaches is an example of how existing practices could be improved to better support deep‐sea mineral management. A case study is provided that highlights the current challenges within the legislative framework of New Zealand. Integr Environ Assess Manag 2022;18:664–673. © 2021 SETAC Key Points: The development of deep‐sea mining requires a considered balance between the needs of society for mineral resources, the protection of ecosystems that are poorly understood, and confidence that local communities will not bear the social costs of poor or misunderstood implementation and management.Standard ecotoxicity tests using a few species need to be adapted to develop tests that assess risks to ecosystem structure and function using species that are valued by local communities in the South Pacific, and relevant to locations of proposed deep seabed mining.A fully accessible shared database of deep‐sea knowledge including biodiversity, habitat structure, and ecosystem services should be available to all stakeholders.The new modeling method can be applied elsewhere to prepare for the adverse effects of rain following a bushfire by minimizing sediment in runoffs. [ABSTRACT FROM AUTHOR]

Subtidal marine sediments are one of the planet's primary carbon stores and strongly influence the oceanic sink for atmospheric CO2. By far the most widespread human activity occurring on the seabed is bottom trawling/dredging for fish and shellfish. A global first‐order estimate suggested mobile demersal fishing activities may cause 0.16–0.4 Gt of organic carbon (OC) to be remineralized annually from seabed sediment carbon stores (Sala et al., 2021). There are, however, many uncertainties in this calculation. Here, we discuss the potential drivers of change in seabed sediment OC stores due to mobile demersal fishing activities and conduct a literature review, synthesizing studies where this interaction has been directly investigated. Under certain environmental settings, we hypothesize that mobile demersal fishing would reduce OC in seabed stores due to lower production of flora and fauna, the loss of fine flocculent material, increased sediment resuspension, mixing and transport and increased oxygen exposure. Reductions would be offset to varying extents by reduced faunal bioturbation and community respiration, increased off‐shelf transport and increases in primary production from the resuspension of nutrients. Studies which directly investigated the impact of demersal fishing on OC stocks had mixed results. A finding of no significant effect was reported in 61% of 49 investigations; 29% reported lower OC due to fishing activities, with 10% reporting higher OC. In relation to remineralization rates within the seabed, four investigations reported that demersal fishing activities decreased remineralization, with three reporting higher remineralization rates. Patterns in the environmental and experimental characteristics between different outcomes were largely indistinct. More evidence is urgently needed to accurately quantify the impact of anthropogenic physical disturbance on seabed carbon in different environmental settings and to incorporate full evidence‐based carbon considerations into global seabed management. [ABSTRACT FROM AUTHOR]

Hundreds of studies have surveyed plastic debris in surface ocean gyre and convergence zones, however, comprehensive microplastics (MPs, ≤5 mm) assessments beneath these surface accumulation areas are lacking. Using in situ high‐volume filtration, Manta net and MultiNet sampling, combined with micro‐Fourier‐transform‐infrared imaging, we discovered a high abundance (up to 244.3 pieces per cubic meter [n m−3]) of small microplastics (SMPs, characteristically <100 μm) from the surface to near‐sea floor waters of the remote South Atlantic Subtropical Gyre. Large horizontal and vertical variations in the abundances of SMP were observed, displaying inverse vertical trends in some cases. SMP abundances in pump samples were more than two orders of magnitude higher than large microplastics (LMPs, >300 μm) concurrently collected in MultiNet samples. Higher‐density polymers (e.g., alkyd resins and polyamide) comprised >65% of the total pump sample count, highlighting a discrepancy between polymer compositions from previous ocean surface‐based surveys, typically dominated by buoyant polymers such as polyethylene and polypropylene. Contrary to previous reports stating LMP preferentially accumulated at density gradients, SMP with presumably slower sinking rates are much less influenced by density gradients, thus resulting in a more even vertical distribution in the water column, and potentially longer residence times. Overall, our findings suggest that SMP is a critical and largely underexplored constituent of the oceanic plastic inventory. Additionally, our data support that weak current systems contribute to the formation of SMP hotspots at depth, implying a higher encounter rate for subsurface particle feeders. Our study unveils the prevalence of plastics in the entire water column, highlighting the urgency for more quantification of the deep‐ocean MP, particularly the smaller size fraction, to better understand ecosystem exposure and to predict MP fate and impacts. [ABSTRACT FROM AUTHOR]

Primary productivity in the ocean plays a major role in the global carbon cycle. To estimate its changes through geological time, different sedimentary proxies are used. However, the relative weights of the various processes driving the sedimentary accumulation of organic matter are not fully constrained or represent the flux of specific algal classes. Here, we compare sea‐surface chlorophyll‐a (SSchla) abundance estimated from remote sensing data over the last 20 years with the sedimentary concentration of its derivatives (i.e., chlorin) on a suite of 140 core‐top sediments from different biogeochemical regions. We estimate with field data that only 0.33% of SSchla in tropical and subtropical regions is transferred to surface sediments in the form of chlorin. Despite the small fraction of chlorin that arrive to the sea‐floor, the sedimentary spatial distribution of chlorin is driven primarily by SSchla concentration in high and moderate productivity locations (SSchla > 0.20 mg·m−3). Our calibration paves the way for the use of chlorin as quantitative proxies of primary productivity in paleoreconstructions and cautions on their use in low primary productivity settings. Plain Language Summary: Chlorophyll‐a derivatives named chlorin are commonly used to reconstruct past primary productivity. However, their value has been questioned as they are posited to be controlled by diagenetic processes and often limited to draw qualitative inferences on the carbon cycle. In fact, most proxies have not been globally appraised with ocean biogeochemical data. Here, we use a combination of remote sensing and geochemical data to provide the first calibration of chlorin proxy. We estimate that 0.33% of the chlorophyll‐a produced in surface waters is transferred to surface sediments. Despite the small fraction of chlorin that arrive to the sea‐floor, we show chlorin concentration is spatially correlated with sea‐surface chlorophyll‐a in high and moderate productivity locations (SSchla > 0.20 mg·m−3). Our calibration paves the way for the use of chlorin as quantitative proxies of primary productivity in past periods and cautions on their use in low primary productivity settings. Key Points: Chlorin concentration higher than 1 μg·g−1 reflects chlorophyll‐a abundance in tropical and subtropical surface watersThe transfer of chlorophyll‐a from the ocean surface to sediments at low latitudes (40°N–40°S) is estimated to be 0.33%Chlorin are a potential proxy to estimate quantitatively past primary productivity changes in high and moderate productivity regions [ABSTRACT FROM AUTHOR]

Anthropogenic debris including microparticles (<5 mm) are ubiquitous in marine environments. The Salish Sea experiences seasonal fluctuations in precipitation, river discharge, sewage overflow events, and tourism—all variables previously thought to have an impact on microparticle transport and concentrations. Our goals are two‐fold: 1) describe long‐term microparticle contamination data including concentration, type, and size; and 2) determine if seasonal microparticle concentrations are dependent on environmental or tourism variables in Elliott Bay, Salish Sea. We sampled 100 L of seawater at a depth of approximately 9 m at the Seattle Aquarium, Seattle, Washington State, United States, approximately every two weeks from 2019 through 2020 and used an oil extraction protocol to separate microparticles. We found that microparticle concentrations ranged from 0 to 0.64 particles L−1 and fibers were the most common type observed. Microparticle concentrations exhibited a breakpoint on 10 April 2020, where estimated slope and associated microparticle concentration significantly declined. Further, when considering both environmental as well as tourism variables, temporal microparticle concentration was best described by a mixed‐effects model, with tourism as the fixed effect and the person counting microparticles as the random effect. Although monitoring efforts presented set out to identify effects of seasonality and interannual differences in microparticle concentrations, it instead captured an effect of decreased tourism due to the global Covid‐19 pandemic. Long‐term monitoring is critical to establish temporal microparticle concentrations and to help researchers understand if there are certain events, both seasonal and sporadic (e.g., rain events, tourism, or global pandemics), when the marine environment is more at risk from anthropogenic pollution. Environ Toxicol Chem 2022;41:917–930. © 2021 Seattle Aquarium. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Anthropogenic microfibers, a ubiquitous environmental contaminant, can be categorized as synthetic, semisynthetic, or natural according to material of origin and production process. Although natural fibers, such as cotton and wool, originated from natural sources, they often contain chemical additives, including colorants (e.g., dyes, pigments) and finishes (e.g., flame retardants, antimicrobial agents, ultraviolet light stabilizers). These additives are applied to textiles during production to give textiles desired properties like enhanced durability. Anthropogenically modified "natural" and semisynthetic fibers are sufficiently persistent to undergo long‐range transport and accumulate in the environment, where they are ingested by biota. Although most research and communication on microfibers have focused on the sources, pathways, and effects of synthetic fibers in the environment, natural and semisynthetic fibers warrant further investigation because of their abundance. Because of the challenges in enumerating and identifying natural and semisynthetic fibers in environmental samples and the focus on microplastic or synthetic fibers, reports of anthropogenic microfibers in the environment may be underestimated. In this critical review, we 1) report that natural and semisynthetic microfibers are abundant, 2) highlight that some environmental compartments are relatively understudied in the microfiber literature, and 3) report which methods are suitable to enumerate and characterize the full suite of anthropogenic microfibers. We then use these findings to 4) recommend best practices to assess the abundance of anthropogenic microfibers in the environment, including natural and semisynthetic fibers. By focusing exclusively on synthetic fibers in the environment, we are neglecting a major component of anthropogenic microfiber pollution. Environ Toxicol Chem 2022;41:822–837. © 2021 SETAC [ABSTRACT FROM AUTHOR]

Fragrance encapsulates (FEs) are designed to deliver fragrance components, notably in laundry care products. They are made of thermoset polymeric shells surrounding the fragrance content. These materials enter the environment mainly during laundry washing, but little is known about their distribution in and impact on the environment. The aim of the present study was to estimate the environmental concentrations of FE shells in freshwater, sediment, and soil compartments for 34 selected countries and to compare them with ecotoxicological effects. Probabilistic material flow analysis was used to estimate worst‐case predicted environmental concentrations (PECs). The lowest freshwater PEC was predicted for Finland (0.00011 µg/L) and the highest for Belgium (0.13 µg/L). Accumulation of FE shells between 2010 and 2019 was considered for sediments and sludge‐treated soils. The PECs in sediments ranged from 3.0 µg/kg (Finland) to 3400 µg/kg (Belgium). For sludge‐treated soil, the concentration was estimated to be between 0 (Malta and Switzerland) and 3600 µg/kg (Vietnam). Ecotoxicological tests showed no effects for FE shells at any tested concentration (up to 2700 µg/L freshwater, 5400 µg/kg sediment, and 9100 µg/kg soil), thus not allowing derivation of a predicted‐no‐effect concentration (PNEC). Therefore, to characterize the environmental risks, the PEC values were compared with highest‐observed‐no‐effect concentrations (HONECs) derived from ecotoxicological tests. The PEC/HONEC ratios were 9.3 × 10–6, 0.13, and 0.04 for surface waters, sediments, and sludge‐treated soils, respectively, which are much below 1, suggesting no environmental risk. Because the PEC values constitute an upper boundary (no fate considered) and the HONEC values represent a lower boundary (actual PNEC values based on NOECs will be higher), the current risk estimation can be considered a precautionary worst‐case assessment. Environ Toxicol Chem 2022;41:905–916. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Disturbance of marine sediments results in the remineralization of sedimentary organic matter (OM) and impacts upon natural burial processes. Management interventions which restrict or remove activities that cause seabed disturbance may offer effective strategies to protect the most vulnerable of these shelf sea OM stores, offering new opportunities to deliver climate mitigation actions. While the largest quantities of OM are often stored in the expansive offshore regions of continental shelves and might therefore suggest appropriate zones for management interventions to protect vulnerable OM stores, our results highlight that these offshore regions generally contain OM of low reactivity. Conversely, inshore and coastal sediments store significant quantities of highly reactive OM that is at greater risk of remineralization when disturbed. The marked spatial disparities between OM reactivity across shelf sea sedimentary environments highlights the need to focus emergent policy and future management interventions toward the protection of inshore and coastal sediments. Plain Language Summary: If disturbed, the organic carbon within seafloor sediments can potentially be converted to carbon dioxide and a portion lost to the atmosphere, where it potentially contributes to climate change. Our results highlight that the reactivity (biodegradability) of sedimentary carbon across shelf seas is highly variable with low reactivity organic matter found in the offshore region, while organic matter within inshore and coastal sediments can be highly reactive and potentially vulnerable to break‐down when disturbed. These differences in organic matter reactivity highlight the need to focus emergent management interventions that can deliver protection toward the most vulnerable organic matter stores in inshore and coastal sediments. Key Points: Within most shelf sediments organic matter (OM) is generally of low reactivity (i.e., low labile OM content) and resistant to remineralizationMuddy nearshore sediments hold large quantities of high reactivity OM which is at risk of remineralization when disturbedPolicy interventions that seek to protect reactive OM should prioritize near‐shore sediment OM over the resilient OM in many shelf seas [ABSTRACT FROM AUTHOR]

Deep water formation (DWF) in the North Western Mediterranean (NWMed) is a key feature of Mediterranean overturning circulation. DWF changes under global warming may have an impact on the Mediterranean biogeochemistry and marine ecosystem. Here we analyze the deep convection in the Gulf of Lions (GoL) in a changing climate using a regional climate system model with a horizontal resolution high enough to represent DWF. We find that under the RCP8.5 scenario the NWMed DWF collapses by 2040–2050, leading to a 92% shoaling in the winter mixed layer by the end of the century. The collapse is related to a strengthening of the vertical stratification in the GoL caused by changes in properties of Modified Atlantic Water and Levantine Intermediate Water, being their relative contribution to the increase of the stratification 57.8% and 42.2%, respectively. The stratification changes also alter the Mediterranean overturning circulation and the exchange with the Atlantic. Plain Language Summary: The deep water formation (DWF) that takes place in the North Western Mediterranean is one of the main drivers of the Mediterranean circulation. Earth's climate warming may affect the DWF, which could trigger large impacts on the Mediterranean ecosystems. This study analyzes the effect of climate change on the DWF in the Gulf of Lions using a Regional Climate System Model. We find out that under a high greenhouse gasses emission scenario the DWF in the North Western Mediterranean collapses by mid‐21st century. The collapse is mostly driven by changes in the temperature and salinity of surface and intermediate waters, which increases the stratification in the water column, hampering the deep convection. This DWF collapse in the Gulf of Lions reflects on the flows exchanged between the Atlantic Ocean and the Mediterranean Sea through the Strait of Gibraltar, which evidence changes in the Mediterranean circulation. Key Points: The North Western Mediterranean deep water formation (DWF) collapse by mid‐21st century under the RCP8.5 scenarioThe collapse is mostly driven by changes in the properties of the Modified Atlantic Water and Levantine Intermediate WaterThe DWF collapse is associated to changes in fluxes through the Strait of Gibraltar [ABSTRACT FROM AUTHOR]

Holothurians are marine invertebrates that are among the most widespread benthic megafauna communities by both biomass and abundance in shallow‐water and deep‐sea ecosystems, their functions supporting important ecological services worldwide. Despite their simple appearance as sea cucumbers, holothurians show a wide range of feeding practices. However, information on what and how these animals eat is scattered and potentially confusing. We provide a comprehensive review of holothurian nutrition in coastal and deep‐sea ecosystems. First, we describe morphological aspects of holothurian feeding and the ultrastructure of tentacles. We discuss the two processes for food capture, concluding that mucus adhesion is likely the main method; two mucous cells, type‐1 and type‐2, possibly allow the adhesion and de‐adhesion, respectively, of food particles. Secondly, this review aims to clarify behavioural aspects of holothurian suspension‐ and deposit‐feeding. We discuss the daily feeding cycle, and selective feeding strategies. We conclude that there is selectivity for fine and organically rich particles, and that feeding through the cloaca is also a route for nutrient absorption. Third, we provide a wide description of the diet of holothurians, which can be split into two categories: living and non‐living material. We suggest that Synallactida, Molpadida, Persiculida, Holothuriida and Elasipodida, ingest the same fractions, and emphasise the importance of bacteria in the diet of holothurians. [ABSTRACT FROM AUTHOR]

The biological carbon pump is a key component of the marine carbon cycle. This surface‐to‐deep flux of carbon is usually assumed to follow a simple power law function, which imposes that the surface export flux is attenuated throughout subsurface waters at a rate dictated by the parameterization exponent. This flux attenuation exponent is widely assumed as constant. However, there is increasing evidence that the flux attenuation varies both spatially and seasonally. While the former has received some attention, the consequences of the latter have not been explored. Here we aim to fill the gap with a theoretical study of how seasonal changes in both flux attenuation and sinking speed affect nutrient distributions and carbon fluxes. Using a global ocean‐biogeochemical model that represents detritus explicitly, we look at different scenarios for how these varies seasonally, particularly the relative "phase" with respect to solar radiation and the "strength" of seasonality. We show that the sole presence of seasonality in the model‐imposed flux attenuation and sinking speed leads to a greater transfer efficiency compared to the non‐seasonal flux attenuation scenario, resulting in an increase of over 140% in some cases when the amplitude of the seasonality imposed is 60% of the non‐seasonal base value. This work highlights the importance of the feedback taking place between the seasonally varying flux attenuation, sinking speed and other processes, suggesting that the assumption of constant‐in‐time flux attenuation and sinking speed might underestimate how much carbon is sequestered by the biological carbon pump. Key Points: The inclusion of seasonal variability in the flux attenuation parameter is found to increase the particulate organic carbon transfer to depthThe increase observed is sensitive to the relative phase between the flux attenuation and the solar radiationA constant‐in‐time flux attenuation might underestimate how much carbon is sequestered by the ocean [ABSTRACT FROM AUTHOR]

The pollution of the marine environment with microplastics is pervasive. However, microplastic concentrations in the seawater are lower than the number of particles entering the oceans, suggesting that plastic particles accumulate in environmental sinks. Yet, the exact long‐term sinks related to the "missing plastic" phenomenon are barely explored. Sediments in nearshore biogenic habitats are known to trap large amounts of microplastics, but also the three‐dimensional structures of coral reefs might serve as unique, living long‐term sinks. The main framework builders, reef‐building corals, have been shown to ingest and overgrow microplastics, potentially leading to a deposition of particles in reef structures. However, little is known about the number of deposited particles and the underlying processes determining the permanent deposition in the coral skeletons. To test whether corals may act as living long‐term sink for microplastic, we exposed four reef‐building coral species to polyethylene microplastics (200 particles L−1) in an 18‐month laboratory experiment. We found microplastics in all treatment specimens, with low numbers of particles trapped in the coral tissue (up to 2 particles per cm2) and much higher numbers in the skeleton (up to 84 particles per cm3). The numbers of particles accumulated in the coral skeletons were mainly related to coral growth (i.e., skeletal growth in volume), suggesting that deposition is a regularly occurring stochastic process. We estimate that reef‐building corals may remove 0.09%–2.82% of the bioavailable microplastics from tropical shallow‐reef waters per year. Our study shows for the first time that microplastic particles accumulate permanently in a biological sink, helping to explain the "missing plastic" phenomenon. This highlights the importance of coral reefs for the ecological balance of the oceans and reinforces the need to protect them, not only to mitigate the effects of climate change but also to preserve their ecosystem services as long‐term sink for microplastic. [ABSTRACT FROM AUTHOR]

Rivers and streams are a primary transport vector for microplastics (MPs), connecting terrestrial sources to marine environments. While previous studies indicated that pore‐scale MPs can accumulate in streambed sediments, the specific MPs transport and retention mechanisms in fluvial systems remain poorly understood. As part of this technical note, we present a novel method for a quantitative analysis of the spatiotemporal transport and retention of pore‐scale MPs in an experimental flume. A continuous mass balance for MPs in surface water was achieved using two online fluorometers, while a laser‐induced Fluorescence‐Imaging‐System was developed to track and quantify the spatial migration of MPs through the streambed sediments. The detection limit was <1 μg/L for 1 μm polystyrene microbeads with the fluorometers and 3 μg/L for the Fluorescence‐Imaging‐System. The system was able to quantitatively track the advective transfer of MPs into the streambed sediments: a process that has yet not been observed experimentally. Results showed that MPs infiltrated into the streambed sediments up to a depth twice the bedform amplitude. This work provides a novel experimental method to quantitatively monitor MP transport through porous media and advective exchange of MP across the streambed interface. Key Points: Novel methodology for the analysis of microplastic (MP) transport in a water flumeQuantitative, spatiotemporal information of MPs through fluorometric techniquesFirst direct observation of advective transport of MPs through the hyporheic zone using natural sediments [ABSTRACT FROM AUTHOR]

The westernmost Mediterranean is one of the most sensitive areas to global climate change and high sedimentation rates allow recording high frequency variability. We present a high‐resolution paleotemperature reconstruction over the last 35 kyr using, for the first time, four independent organic sea surface temperature (SST) proxies (UK'37, TEXH86, RI‐OH' and LDI) based on alkenones, (hydroxy) isoprenoid GDGTs, and long‐chain diols. We also generated a δ18O of planktonic foraminifera G. bulloides record together with records of bulk parameters (total organic carbon content, δ13Corg) and the accumulation rates of different biomarkers to provide insights into terrestrial input and primary producers. All derived‐SST records showed similar trends over the last 35 kyr, revealing abrupt temperature variations during the last seven Dansgaard‐Oeschger (D/O) cycles, the three Heinrich (H) events, the Last Glacial Maximum, and the Younger Dryas. H3 is recognized as the coldest event, while H1 was recorded by all SST proxies as the most abrupt one. In general, TEXH86‐, RI‐OH'‐ and LDI‐SST estimates were lower than those obtained from UK'37. The LDI paleothermometer recorded the largest range of absolute SSTs over the whole period (ca. 20°C) followed by RI‐OH' (ca. 16°C). TEXH86, RI‐OH' and LDI proxies reflected sudden SST changes during the D/O 6 and 5 particularly well. Low BIT values and the abundance of C32 1,15‐diol in range with typical marine values indicated only minor input of continental organic matter. Accumulation rates of different lipid biomarkers were generally modulated by D/O cycles, suggesting enhanced productivity during D/O interstadials and the Bölling‐Alleröd period. Key Points: Four independent lipid‐based paleothermometers are applied in the westernmost MediterraneanHigh‐resolution sea surface temperature records reveal abrupt changes during Dansgaard‐Oeschger and Heinrich events over the last 35 kyrElevated accumulation rates of lipid biomarkers are recorded during Dansgaard‐Oeschger interstadials [ABSTRACT FROM AUTHOR]

The northward expansion of round sardinella (Sardinella aurita) in the Mediterranean Sea, together with declines and fluctuations in biomass and landings of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) observed in recent decades, may suggest potential inter-specific competition in the pelagic domain. The coexistence of sympatric zooplanktivorous fish species might therefore be exposed in part to trophic niche overlap and competition for food. Combining visual diet characterization under the microscope with DNA metabarcoding from stomach contents of fish collected in spring results show that predation on relatively large krill is equally important for sardinella than for the other two niche overlapping species. Furthermore, an important overlap is found in their isotopic niche, especially with anchovy, using nitrogen (δ15N) and carbon (δ13C) stable isotopes in muscle tissue. In fact, the three fish species are able to feed effectively in the whole prey size spectrum available during the sampled season, from the smallest diatoms and copepods to the larger prey (i.e., decapods and euphausiids), including fish larvae. Moreover, effective predation upon other large prey like siphonophores, which is observed only when multi-proxy analyses in stomach contents are applied, might also be relevant in the diet of sardinella. The overlapping diet composition in spring, together with the effective use of food resource by sardinella, can be of special interest in potential future scenarios with warmer water temperature leading to lower zooplankton and/or higher jellyfish availability, where sardinella may take advantage over other species due to its feeding plasticity. [ABSTRACT FROM AUTHOR]

Microplastic pollution has been reported from coral reef systems all over the tropics. Exposure to microplastics has several negative impacts on coral health, such as bleaching, tissue necrosis, or an impairment of the coral's immune system. Despite this potential risk for reef systems, the controlling processes for microplastics dispersion and accumulation in reef sediments are still largely under‐studied. Presented here is a study of microplastics (125 µm to 5 mm) distribution in two tropic atoll reef platforms in Kepulauan Seribu, Indonesia. Sediment samples were collected in different facies zones within the reef platform. Microplastics were concentrated using density floatation and characterized by light and scanning electron microscopy. Some particles were identified as polypropylene using micro‐Fourier transform infrared spectroscopy. All recovered microplastics were classified as secondary microplastics, likely derived from marine and local sources, with fibres as the most abundant type. Microplastics are showing similar transport and accumulation behaviour as fine siliciclastic grains. The abundance of microplastic is controlled by the proximity to the source area of larger plastic debris and hydrodynamic processes. Microplastics are not only present in low energy environments but also high energy settings such as the reef crest. Processes that contribute to accumulation in reef sediments are biofouling, interlocking and the creation of compound grains. Microplastics are present in sediment close to the seafloor (0 to 3.5 cm) but also at depths between 3.5 cm and 7.0 cm. Microplastic particles from below 3.5 cm are unlikely to be remobilized under modal weather conditions in the studied equatorial reefs. Subtidal reef sediment therefore can be regarded as a permanent sink for microplastics. The study shows that microplastics in coral reef environments deserve careful consideration since microplastics pose an additional threat to corals and their ability as framework builders in reef systems. [ABSTRACT FROM AUTHOR]

To better quantify the ocean's biological carbon pump, we resolved the diversity of sinking particles that transport carbon into the ocean's interior, their contribution to carbon export, and their attenuation with depth. Sinking particles collected in sediment trap gel layers from four distinct ocean ecosystems were imaged, measured, and classified. The size and identity of particles was used to model their contribution to particulate organic carbon (POC) flux. Measured POC fluxes were reasonably predicted by particle images. Nine particle types were identified, and most of the compositional variability was driven by the relative contribution of aggregates, long cylindrical fecal pellets, and salp fecal pellets. While particle composition varied across locations and seasons, the entire range of compositions was measured at a single well‐observed location in the subarctic North Pacific over one month, across 500 m of depth. The magnitude of POC flux was not consistently associated with a dominant particle class, but particle classes did influence flux attenuation. Long fecal pellets attenuated most rapidly with depth whereas certain other classes attenuated little or not at all with depth. Small particles (<100 μm) consistently contributed ∼5% to total POC flux in samples with higher magnitude fluxes. The relative importance of these small particle classes (spherical mini pellets, short oval fecal pellets, and dense detritus) increased in low flux environments (up to 46% of total POC flux). Imaging approaches that resolve large variations in particle composition across ocean basins, depth, and time will help to better parameterize biological carbon pump models. Plain Language Summary: Sinking particles transport carbon from the surface ocean to depth where carbon is sequestered from the atmosphere for long time periods. The amount of carbon transported by this process is difficult to quantify, in part because of the complex ecological interactions that generate sinking particles and alter downward transport. This study combined chemical measurements with detailed imagery of sinking particles collected in drifting sediment traps to survey how different types of particles affect carbon export across five locations. The biological characteristics of imaged particles can be used to reasonably predict carbon export and its attenuation with depth. Measured particles were classified into nine different categories, including various types of aggregates, organisms, and zooplankton fecal pellets. The amount of sinking carbon was not related to the dominance of any specific particle type, but each type transported carbon with differing efficiencies. Episodic presence of fecal pellets produced by gelatinous zooplankton had a large influence on transport of carbon to depth. Particles often considered too small to contribute to carbon export (<100 µm) were consistently important, especially in low flux environments, and often attenuated relatively little with depth. Resolving biological details of sinking particles improves our ability to quantify the ocean's carbon cycle. Key Points: Carbon flux into the deep ocean by sinking particles can be reasonably predicted from images of collected particle fluxSinking particle type and trophic processing affect attenuation of carbon flux with depthParticles smaller than 100 μm can be an important component of sinking carbon and some attenuated little with depth [ABSTRACT FROM AUTHOR]

Deep‐water depositional systems are the ultimate sink for vast quantities of terrigenous sediment, organic carbon and anthropogenic pollutants, forming valuable archives of environmental change. Our understanding of the distribution of these particles and the preservation of environmental signals, in deep‐water systems is limited due to the inaccessibility of modern systems, and the incomplete nature of ancient systems. Here, the deposit of a physically modelled turbidity current was sampled (n = 49) to determine how grain size and grain type vary spatially. The turbidity current had a sediment concentration of 17%. The sediment consisted of, by weight, 65% quartz sand (2.65 g/cm3), 17.5% silt (2.65 g/cm3), 7.5% clay (2.60 g/cm3) and 5% each of sand‐grade garnet (3.90 g/cm3) and microplastic fragments (1.50 g/cm3). The grain size and composition of each sample was determined using laser diffraction and density separation, respectively. The results show that: (a) bulk grain size coarsened axially downstream on the basin floor challenging the notion that basin floor deposits fine radially from an apex upon becoming unconfined; (b) no sample composition matched the input composition of the flow, indicating that allogenic signals can be autogenically shredded and spatially variable in sediment gravity flow deposits; and (c) microplastic fragments were concentrated in levee and lateral basin floor fringe positions; however, microplastic concentrations in these positions were lower than input, suggesting microplastics bypassed the sampled positions. These findings have implications for: (a) the development of 'finger‐like' geometries and facies distributions observed in modern and ancient systems; (b) interpreting environmental signals in the stratigraphic record; and (c) predicting the distribution of microplastics on the sea floor. [ABSTRACT FROM AUTHOR]

Paleoproductivity is reconstructed across a Mediterranean benchmark record, the Early/Middle Pleistocene Montalbano Jonico section, cropping out in southern Italy. High‐resolution coccolithophore and alkenone data (C37 and C37:2/C38:2 ratio) were collected in order to extend the data set on Mediterranean paleoproductivity pattern and forcing mechanisms. The multi‐proxy record indicates low productivity during glacial and stadial phases and enhanced productivity during interglacial and interstadials. Increased surface water turbidity, cold‐water temperature and polar‐subpolar low salinity water incursion appear as the dominant controls for low productivity during Marine Isotope Stage (MIS) 20. Enhanced productivity during MIS 19c was sustained by warmer surface waters, coupled with a seasonal precipitation regime, providing higher nutrient availability. Productivity increases during interstadials with respect to stadials, in relation with enhanced land‐derived nutrient input through river discharge during wetter winters. The productivity scenario we propose is similar to those reconstructed from deep‐sea records in the central and western Mediterranean during Dansgaard‐Oeschger oscillations over the last 70 ka. This indicates that similar forcing mechanisms acted on productivity dynamics on a regional scale over different times. We suggest that migration of the westerly wind system over the Mediterranean and the polar water inflow influenced productivity on a regional scale. The acquired data set provides new evidences on the environmental significance of the C37:2/C38:2 ratio and on its relation with surface water productivity. Plain Language Summary: Coccolithophores are calcifying unicellular algae and one of the most important marine phytoplankton group. In the present‐day oceans their distribution strongly depends on environmental factors such as nutrient concentration, surface water temperature, sunlight availability. Therefore, changes in fossil coccolithophore assemblages are successfully used for paleoclimatic and paleoceanographic reconstructions. They are also the source of organic compounds (the alkenones), which provide estimation of paleotemperature and paleoproductivity. We used variations of coccolithophore assemblages and of alkenones to identify paleoproductivity variations in the central Mediterranean, in a nearshore environment, during a key Quaternary paleoclimate interval. Our approach benefited of other paleoenvironmental indicators such as sea surface temperature and stable oxygen and carbon isotopes available at the studied section. We find that past climate changes clearly affected coccolithophore productivity at our site. Paleoproductivity was clearly favored by warm surface waters and by seasonal nutrient availability resulting by enhanced humidity over the central Mediterranean region. Our data also provide new indications on the relation between coccolithophore assemblage and alkenone variations through climate phases which may have future implication on their use for paleoenvironmental reconstruction. Key Points: Coccolithophore and alkenones underline productivity changes in a reference Early/Middle Pleistocene record from the central MediterraneanProductivity proxies reflect millennial‐scale climate changes with low/high values during cold and drier/warm and wetter conditionsSimilarity with the Dansgaard‐Oeschger oscillations scenario suggests a common regional climate forcing over productivity through time [ABSTRACT FROM AUTHOR]

The North Icelandic Jet (NIJ) is the densest component of the Denmark Strait Overflow Water, feeding the abyssal limb of the Atlantic Meridional Overturning Circulation. Here, by using observational and numerical model data, we explore the formation of overflow water on the Icelandic shelf, the mechanisms involved, and its potential contribution to the NIJ. The sparse observational data on the western Icelandic shelf for the month of February shows top-to-bottom mixing on the shelf, distinct and well separated from the dense water offshore, with densities larger than 27.8 kg/m³ in some years. Using a 1-D mixing model and winter heat flux reanalysis, we suggest that waters with densities exceeding 27.8 kg/m³ are likely to be formed on the shelf in most years by the end of winter. High-resolution numerical model data shows that the transformation of the Atlantic inflow along the northwest Icelandic shelf generates a dense plume whose waters feed into the NIJ. The bulk of the plume cascades downslope north of Iceland, funneled through deep cross-shelf troughs, with some cascading occurring west of Iceland as well. During years of strong cascading events (2008, 2013, and 2016), the modeled dense plume potentially feeds up to 21% of the NIJ transport at the Siglunes and Kögur sections. Back-tracked Lagrangian particle trajectories confirm that the western Icelandic shelf is a source of the NIJ. The dense plume transport and variability are found to be dependent on the total oceanic heat loss west of Iceland and along Denmark Strait. [ABSTRACT FROM AUTHOR]

Plastic pollution has pervaded almost every facet of the biosphere, yet we lack an understanding of consumption risk by marine species at the global scale. To address this, we compile data from research documenting plastic debris ingestion by marine fish, totaling 171,774 individuals of 555 species. Overall, 386 marine fish species have ingested plastic debris including 210 species of commercial importance. However, 148 species studied had no records of plastic consumption, suggesting that while this evolutionary trap is widespread, it is not yet universal. Across all studies that accounted for microplastics, the incidence rate of plastic ingested by fish was 26%. Over the last decade this incidence has doubled, increasing by 2.4 ± 0.4% per year. This is driven both by increasing detection of smaller sized particles as a result of improved methodologies, as well as an increase in fish consuming plastic. Further, we investigated the role of geographic, ecological, and behavioral factors in the ingestion of plastic across species. These analyses revealed that the abundance of plastic in surface waters was positively correlated to plastic ingestion. Demersal species are more likely to ingest plastic in shallow waters; in contrast, pelagic species were most likely to consume plastic below the mixed layer. Mobile predatory species had the highest likelihood to ingest plastic; similarly, we found a positive relationship between trophic level and plastic ingestion. We also find evidence that surface ingestion‐deep sea egestion of microplastics by mesopelagic myctophids is likely a key mechanism for the export of microplastics from the surface ocean to the seafloor, a sink for marine debris. These results elucidate the role of ecology and biogeography underlying plastic ingestion by marine fish and point toward species and regions in urgent need of study. [ABSTRACT FROM AUTHOR]

The agribusiness sector represents an economic sector of particular importance and with the highest employment rate. The sector is very complex due to the characteristics of the organizations that are part of it and need to base their competitive advantage on innovations often obtained by sharing knowledge with third organizations. The study highlights the main theories of the key organizational factors that influence the knowledge transfer process between universities and firms and presents the first results of an exploratory analysis, aimed to understand what are the key organizational factors identified by the entrepreneurs of the agribusiness sector that affect knowledge transfer for innovation, in particular from universities and high educational institutions. The study can help agribusiness organizations to activate and manage their interorganizational relationships in order to improve their mechanism of knowledge sharing for innovation and shed light for scholars on an important business sector. [ABSTRACT FROM AUTHOR]