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  • Other Sources  (8,202)
  • 2020-2024  (8,202)
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  • 1
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    Carbon budget of methane seepages in the Haiyang 4 Area in the northern slope of the South China sea (2024)
    Elsevier
    Details
    Publication Date: 2024-07-03
    Description: Highlights • All investigated sites are in quiescent stage. Multi layers of clam shell debris were the ancient sediment surfaces during high methane flux. • Current fluxes contribute to less than 2 wt % of authigenic carbonates and 2 wt % iron sulfide minerals being precipitated in 600-800 cm sediment. • The sequestration of carbon could be 〉 50 mmol C cm-2 yr-1 under current in situ condition. Abstract Methane seepage records information of the local carbon cycle with respect to the generation, consumption and sequestration of carbon. Here presents the investigation of 7 gravity cores retrieved in 2004 during cruise SO-177 in the Haiyang 4 Area at the northern slope of the South China Sea. Porewater solutes, sulfate, methane, total alkalinity, sulfide and calcium demonstrate currently the weak seep activity. Local carbon cycling and sequestration is also revealed, that dominates by anaerobic oxidation of biogenic methane to dissolved bicarbonate inducing calcium carbonate and iron sulfide minerals (mainly pyrite) precipitation. A reactive transport model was employed to quantify the carbon cycle and budget. Model results show that current methane fluxes contribute to less than 2 wt % of authigenic carbonates and 2 wt % iron sulfide minerals being precipitated in 600–800 cm sediment depth. The sequestration of carbon could be 〉 50 mmol C cm−2 yr−1 under in situ condition. The observed increase of carbonate and iron sulfide minerals at ∼100 cm, however, require higher methane fluxes to shift the zone of anaerobic oxidation of methane upwards to around 1 m below the seafloor, which have occurred during sea level low stands in the geological past. The oscillation of seepage flux contributed to the formation of multiple layers of authigenic carbonates and pyrite, which indicates the high capability of carbon sink and is speculated to be induced by the dissociation of the underlying hydrates triggered by sea level drop and or temperature increase.
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  • 2
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    What Is Missing in Offshore Explosive Ordnance Disposal Risk Assessment? (2024)
    MDPI
    Details
    Publication Date: 2024-07-03
    Description: Offshore explosive ordnance disposal (EOD) in the marine environment is a high-risk activity. Structured risk assessment (RA) can be a helpful tool to provide EOD experts with decision-making support. This paper hypothesizes that existing RA approaches that address unexploded ordnance (UXO) in the sea do not meet the requirements of EOD RA. To test this hypothesis, the paper proposes a novel categorization tool. It uses five review criteria: study type (qualitative vs. quantitative), level of decision-making (strategic vs. applied), risk component (probability vs. consequence), spatial scale (global vs. local), and temporal scale (long-term vs. short-term). The categorization tool is used to identify the requirements of EOD RA and to test whether nine existing RA methods fulfill these requirements. The study finds that none of the investigated RAs meets the requirements and, hence, concludes that a new method should be developed. However, some aspects of the existing studies should be considered when designing a new method. This includes using risk factors (type and mass of explosive material, type and state of the fuze, and water depth) that are relevant for EOD RA. It also involves setting up a directed graph to assess the complex interdependencies between these risk factors.
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  • 3
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    Natural marine bromoform emissions in the fully coupled ocean–atmosphere model NorESM2 (2024)
    Copernicus Publications (EGU)
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    Publication Date: 2024-07-03
    Type: Article , PeerReviewed
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  • 4
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    Thematic assessment on Hazardous Submerged Objects in the Baltic Sea (Submerged Assessment - Warfare Materials in the Baltic Sea) (2024)
    Helsinki Commission – HELCOM
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    Publication Date: 2024-07-03
    Type: Report , NonPeerReviewed
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  • 5
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    Evaluating the physics of outcrop-to-outcrop flow with hydrothermal flow models (2024)
    Wiley | AGU (American Geophysical Union)
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    Publication Date: 2024-07-02
    Type: Article , NonPeerReviewed
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  • 6
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    Automatic mud diapir detection using ANFIS expert systems algorithm; a case study in the Gorgan plain, Iran (2024)
    Springer
    Details
    Publication Date: 2024-07-02
    Description: Automatic seismic data interpretation is a significant method in the exploration of geophysics. Complexities of the subsurface structures and the subsurface wave propagation media, make the decision-making process difficult in seismic data interpretation. Nevertheless, the extent of related knowledge and using the expert system method in seismic data interpretation can mitigate this problem. An expert system is a knowledge-based system that applies its knowledge in a complex and specific area and acts as an expert end-user consultant. This study investigates the design of an ANFIS expert system for mud diapirs detection with seismic data analysis in Gorgan plain. This method was applied to seismic attributes from a complex geological mud diapir bearing structure from south of the Caspian Sea. The south of the Caspian Sea is one of the richest area as petroleum reserves, and the Gorgan plain has various mud diapirs, which act as indicators of hydrocarbon reservoirs. The expert system design process to identify mud diapirs on seismic sections was modeled in two approaches including manual and automatic seismic data interpretation. In the first approach, the experience of the expert was collected by manual interpretation of training data and used to create a knowledge base and inference of the expert system in the second approach. The validation verified the accuracy of this method with an average accuracy of 90.1% according to using minimum knowledge to develop a knowledge base of the designed ANFIS expert system.
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  • 7
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    Geological modelling of petroleum reservoir through multi-scale analysis of faults in complex media (2024)
    Elsevier
    Details
    Publication Date: 2024-07-02
    Description: Highlights • Accurate fault model can be built even when sparse drilling wells are available. • The multiresolution fault model provides information of faults with different sizes. • Fault model provides possibility of tectonic and fluid flow analysis simultaneously. • Modelling of faults in different scales, enable more accurate well path design. • The ANN provides optimized parameters for fault detection by ant tracking algorithm. Modelling faults plays a crucial step in the chain of studies through the first phase of the hydrocarbon exploration and its following studies in reservoir engineering, simulation and field development. This study introduces an innovative and automatic integrated approach that combines seismic multi-attributes and well data for faults modelling. The proposed strategy begins with extracting fault-related seismic attributes commonly used for seismic reservoir characterization. Chaos, variance and curvature attributes, typically highlight large-scale faults that shape the structural framework of the study field. In contrast, small-scale faults, influencing subsurface fluid flow in the fractured reservoir, are modeled using the ant-tracking algorithm applied to seismic data. Small-scale and large-scale fault models, then integrated with the conventional fault model to create an integrated discrete fracture network (DFN). This DFN model incorporates information on both large-scale and small-scale faults. The proposed strategy was applied on a geologically complex petroleum field in Iran. The results, validated using Formation Micro Imager (FMI) data, demonstrate accuracy of the integrated DFN model in comparison to conventional approaches on the studied filed, particularly in capturing small-scale faults. Consequently, it can be concluded that the proposed strategy provides a viable alternative for generating accurate DFN model.
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  • 8
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    Visual Tomography: Physically Faithful Volumetric Models of Partially Translucent Objects (2024)
    IEEE
    Details
    Publication Date: 2024-07-02
    Description: When created faithfully from real-world data, Digital 3D representations of objects can be useful for human or computer-assisted analysis. Such models can also serve for generating training data for machine learning approaches in settings where data is difficult to obtain or where too few training data exists, e.g. by providing novel views or images in varying conditions. While the vast amount of visual 3D reconstruction approaches focus on non-physical models, textured object surfaces or shapes, in this contribution we propose a volumetric reconstruction approach that obtains a physical model including the interior of partially translucent objects such as plankton or insects. Our technique photographs the object under different poses in front of a bright white light source and computes absorption and scattering per voxel. It can be interpreted as visual tomography that we solve by inverse raytracing. We additionally suggest a method to convert non-physical NeRF media into a physically-based volumetric grid for initialization and illustrate the usefulness of the approach using two real-world plankton validation sets, the lab-scanned models being finally also relighted and virtually submerged in a scenario with augmented medium and illumination conditions. Please visit the project homepage at www.marine.informatik.uni-kiel.de/go/vito
    Type: Book chapter , NonPeerReviewed , info:eu-repo/semantics/bookPart
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  • 9
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    The European Ocean Observing System: urgent gaps and recommendations to implement during the UN Ocean Decade (2024)
    Frontiers
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    Publication Date: 2024-07-02
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 10
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    Submarine volcanism in the Sicilian Channel revisited (2024)
    Elsevier
    Details
    Publication Date: 2024-07-02
    Description: Highlights • New geophysical data and samples redefine submarine volcanism in Sicilian Channel. • Three dominant bands of volcanism are distinguished. • Ancient, eroded structures aligned at 120° are tied to faulted banks in the north. • Younger band of similarly aligned volcanism in the south is linked to grabens. • Youngest structures comprise small, dispersed volcanoes with distinct orientation. Abstract The origin and role of volcanism in continental rifts remains poorly understood in comparison to other volcano-tectonic settings. The Sicilian Channel (central Mediterranean Sea) is largely floored by continental crust and represents an area affected by pronounced crustal extension and strike-slip tectonism. It hosts a variety of volcanic landforms closely associated with faults, which can be used to better understand the nature and distribution of rift-related volcanism. A paucity of appropriate seafloor data in the Sicilian Channel has led to uncertainties regarding the location, volume, sources and timing of submarine volcanism. To improve on this situation, we use newly acquired geophysical data (multibeam echosounder and magnetic data, sub-bottom profiles) and dredged seafloor samples to: (i) re-assess the evidence for submarine volcanism in the Sicilian Channel and define its spatial pattern, (ii) infer the relative age and style of magmatism, and (iii) relate this to the dominant tectonic structures in the region. Quaternary rift-related volcanism has been focused at Pantelleria and Linosa, at the northwest boundaries of their respective NW-SE trending grabens. Subsidiary and older volcanic sites potentially occur at the Linosa III and Pantelleria SE seamounts, collectively representing the only sites of recent volcanism that can be directly related to the main rift process. These long-lived polygenetic volcanic landforms have been shaped by magmatism that is directly correlated with extensional faulting and buried igneous bodies. Older volcanic landforms, sharing a similar scale and alignment, occur to the north at Nameless Bank and Adventure Bank. These deeply eroded volcanoes have likely been inactive since the Pliocene and are probably related to earlier stages of crustal thinning and underlying feeder structures in the northern region of the Sicilian Channel. Along a similar alignment, Pinne Bank, SE Pinne Bank and Cimotoe in the northern Sicilian Channel lack a surface volcanic signature but are associated with intrusive bodies or deeply buried volcanic rock masses. Terrible Bank, in the same region, also shows evidence of ancient, polygenetic magmatism, but was subject to significant erosion and lacks a prominent alignment. The much younger volcanism at Graham Volcanic Field and along the northern Capo-Granitola-Sciacca Fault Zone differs markedly from that observed in the other study areas. Here, the low-volume and scattered volcanic activity is driven by shallow-water mafic magma eruptions, which gave rise to small individual cones. These sites are associated with large fault structures away from the main rift axis and may have a distinct magmatic origin. Dispersed active fluid venting occurs across both ancient and young volcanic sites in the region and is directly associated with shallow magmatic bodies within tectonically-controlled basins. Our study provides the foundation for an updated tectonic and magmatic framework for the Sicilian Channel, and for future detailed chronological and geochemical assessment of the sources and evolution of magmatic processes in the region.
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  • 11
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    Glimpsing the 2020 spring bloom in the Strait of Georgia (Canada) with autonomous ferry-based sensors (2024)
    Inter Research
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    Publication Date: 2024-07-02
    Description: Spatiotemporal observations are data rich and offer insights into links between ecological patterns and underlying processes. We present fine-scale autonomous observations from repeated ferry transects in the Strait of Georgia (British Columbia, Canada) during the 2020 spring bloom period using a FerryBox system (temperature, salinity, chlorophyll a fluorescence) and a digital inline holographic microscope. Despite instrument cleaning interruptions related to COVID-19 restrictions, 3 periods from late winter (February) to springtime (March and April) contained 14 days of high-quality holograms (〉70 000) capturing 〉10 500 identifiable micro- to mesoplankton using automatic object detection. The ferry set-up provided automatic data storage through Ocean Networks Canada, which also automatized data flagging and guaranteed remote access. The highest-quality holograms repeatedly covered the central and eastern Strait and showed aspects of bloom succession. Fast-growing diatoms (Skeletonema sp.) emerged first, followed by a diverse assemblage including Chaetoceros spp., Ditylum spp., and Eucampia spp., and by April, larger centric cells prevailed. The combined approach captured local suppression of chlorophyll a fluorescence and diatom concentrations in Fraser River plume waters during the freshet, suggesting fine-scale spatial patterns in seasonal planktonic community composition. This work is among the first of its kind to autonomously generate in situ imaging and physicochemical data with spatiotemporal resolution.
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  • 12
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    Reconstruction of the marine carbonate system at the Western Tropical Atlantic: trends and variabilities from 20 years of the PIRATA program (2024)
    Frontiers
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    Publication Date: 2024-07-02
    Description: The Western Tropical Atlantic Ocean (WTAO) is crucial for understanding CO2 dynamics due to inputs from major rivers (Amazon and Orinoco), substantial rainfall from the Intertropical Convergence Zone (ITCZ), and CO2-rich waters from equatorial upwelling. This study, spanning 1998 to 2018, utilized sea surface temperature (SST) and sea surface salinity (SSS) data from the PIRATA buoy at 8°N 38°W to reconstruct the surface marine carbonate system. Empirical models derived TA and DIC from SSS, with subsequent estimation of pH and fCO2 from TA, DIC, SSS, and SST data. Linear trend analysis showed statistically significant temporal trends: DIC and fCO2 increased and pH decreased, although DIC did not show any trend after data was de-seasoned. Rainfall analysis revealed distinct dry (July to December) and wet (January to June) seasons, aligning with lower and higher freshwater influence, respectively. TA, DIC, and pH correlated positively with SSS, exhibiting higher values during the dry season and lower values during the wet season. Conversely, fCO2 correlated positively with SST, showcasing higher values during the wet season and lower values during the dry season. This emphasizes the influential roles of SSS and SST variability in CO2 solubility within the region.
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  • 13
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    Assessing the impact of CO2-equilibrated ocean alkalinity enhancement on microbial metabolic rates in an oligotrophic system (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-07-02
    Description: Ocean alkalinity enhancement (OAE) is a negative emissions technology (NET) that shows significant potential for climate change mitigation. By increasing the bicarbonate ion concentration in ocean water, OAE could enhance long-term carbon storage and mitigate ocean acidification. However, the side effects and/or potential co-benefits of OAE on natural planktonic communities remain poorly understood. To address this knowledge gap, a mesocosm experiment was conducted in the oligotrophic waters of Gran Canaria. A CO2-equilibrated total alkalinity (TA) gradient was employed in increments of 300 µmol L−1, ranging from ∼ 2400 to ∼ 4800 µmol L−1. This study represents the first attempt to evaluate the potential impacts of OAE on planktonic communities under natural conditions. The results show that net community production (NCP), gross production (GP), community respiration (CR) rates, and the metabolic balance (GP:CR) did not exhibit a linear response to the whole alkalinity gradient. Instead, significant polynomial and linear regression models were observed for all rates up to ΔTA 1800 µmol L−1, in relation to the dissolved inorganic carbon (DIC) concentrations. Notably, the ΔTA 1500 and 1800 µmol L−1 treatments showed peaks in NCP shifting from a heterotrophic to an autotrophic state, with NCP values of 4 and 8 µmol O2 kg−1 d−1, respectively. These peaks and the optimum curve were also reflected in the nanoplankton abundance, size-fractionated chlorophyll a, and 14C uptake data. Furthermore, abiotic precipitation occurred in the highest treatment after day 21, but no impact on the measured parameters was detected. Overall, a damaging effect of CO2-equilibrated OAE in the range applied here on phytoplankton primary production, community metabolism, and composition could not be inferred. In fact, a potential co-benefit to OAE was observed in the form of the positive curvilinear response to the DIC gradient up to the ΔTA 1800 treatment. Further experimental research at this scale is key to gain a better understanding of the short- and long-term effects of OAE on planktonic communities.
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  • 14
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    Deep inflow transport and dispersion in the Gulf of St. Lawrence revealed by a tracer release experiment (2024)
    Nature Research
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    Publication Date: 2024-07-02
    Description: The Gulf of St. Lawrence is increasingly affected by bottom water hypoxia; however, the timescales and pathways of deep water transport remain unclear. Here, we present results from the Deep Tracer Release eXperiment (TReX Deep), during which an inert SF 5 CF 3 tracer was released inshore of Cabot Strait at 279 m depth to investigate deep inflow transport and mixing rates. Dispersion was also assessed via neutrally-buoyant Swish floats. Our findings indicate that the tracer moves inland at 0.5 cm s −1 , with an effective lateral diffusivity of 2 × 10 2 m 2 s −1 over 1 year. Simplified 1D simulations suggest inflow water should reach the estuary head in 1.7 years, with the bulk arriving after 4.7 years. Basin-wide effective vertical diffusivity is around 10 −5 m 2 s −1 over 1 year; however, vertical diffusivity increases near the basin slopes, suggesting that turbulent boundary processes influence mixing. These results are compared to Lagrangian simulations in a regional 3D model to evaluate the capacity to model dispersion in the Gulf.
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  • 15
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    Ensemble modelling to predict the distribution of vulnerable marine ecosystems indicator taxa on data‐limited seamounts of Cabo Verde (NW Africa) (2024)
    Wiley
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    Publication Date: 2024-07-02
    Description: Aim Seamounts are conspicuous geological features with an important ecological role and can be considered vulnerable marine ecosystems (VMEs). Since many deep‐sea regions remain largely unexplored, investigating the occurrence of VME taxa on seamounts is challenging. Our study aimed to predict the distribution of four cold‐water coral (CWC) taxa, indicators for VMEs, in a region where occurrence data are scarce. Location Seamounts around the Cabo Verde archipelago (NW Africa). Methods We used species presence–absence data obtained from remotely operated vehicle (ROV) footage collected during two research expeditions. Terrain variables calculated using a multiscale approach from a 100‐m‐resolution bathymetry grid, as well as physical oceanographical data from the VIKING20X model, at a native resolution of 1/20°, were used as environmental predictors. Two modelling techniques (generalized additive model and random forest) were employed and single‐model predictions were combined into a final weighted‐average ensemble model. Model performance was validated using different metrics through cross‐validation. Results Terrain orientation, at broad scale, presented one of the highest relative variable contributions to the distribution models of all CWC taxa, suggesting that hydrodynamic–topographic interactions on the seamounts could benefit CWCs by maximizing food supply. However, changes at finer scales in terrain morphology and bottom salinity were important for driving differences in the distribution of specific CWCs. The ensemble model predicted the presence of VME taxa on all seamounts and consistently achieved the highest performance metrics, outperforming individual models. Nonetheless, model extrapolation and uncertainty, measured as the coefficient of variation, were high, particularly, in least surveyed areas across seamounts, highlighting the need to collect more data in future surveys. Main Conclusions Our study shows how data‐poor areas may be assessed for the likelihood of VMEs and provides important information to guide future research in Cabo Verde, which is fundamental to advise ongoing conservation planning.
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  • 16
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    Volcanic flank collapse, secondary sediment failure and flow-transition: multi-stage landslide emplacement offshore Montserrat, Lesser Antilles (2024)
    AGU (American Geophysical Union) | Wiley
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    Publication Date: 2024-07-02
    Description: Volcanic flank collapses, especially those in island settings, have generated some of the most voluminous mass transport deposits on Earth and can trigger devastating tsunamis. Reliable tsunami hazard assessments for flank collapse-driven tsunamis require an understanding of the complex emplacement processes involved. The seafloor sequence southeast of Montserrat (Lesser Antilles) is a key site for the study of volcanic flank collapse emplacement processes that span subaerial to submarine environments. Here, we present new 2D and 3D seismic data as well as MeBo drill core data from one of the most extensive mass transport deposits offshore Montserrat, which exemplifies multi-phase landslide deposition from volcanic islands. The deposits reveal emplacement in multiple stages including two blocky volcanic debris avalanches, secondary seafloor failure and a late-stage erosive density current that carved channel-like incisions into the hummocky surface of the deposit about 15 km from the source region. The highly erosive density current potentially originated from downslope-acceleration of fine-grained material that was suspended in the water column earlier during the slide. Late-stage erosive turbidity currents may be a more common process following volcanic sector collapse than has been previously recognized, exerting a potentially important control on the observed deposit morphology as well as on the runout and the overall shape of the deposit. Key Points Landslide emplacement offshore Montserrat included volcanic flank collapses, sediment incorporation, and a late-stage erosive flow Highly erosive flows are likely to be common processes during volcanic flank collapse deposition Pre-existing topography plays a major role in shaping flank collapse-associated mass transport deposits Plain Language Summary Disintegration of volcanic islands can cause very large landslides and destructive tsunamis. To assess the tsunami hazard of such events, it is crucial to understand the processes that are involved in their formation. We present new insights from seismic data and drill cores from a landslide deposit offshore Montserrat, a volcanic island in the Lesser Antilles Arc in the Caribbean. Our analysis reveals the emplacement of landslide material in several stages, including multiple volcanic flank collapses, incorporation of seafloor sediments and an erosive flow that carved channels into the top of the deposit right after its emplacement. We suggest that highly erosive flows are a common process during volcanic flank collapse deposition and that they play a significant role in the shaping of the deposit's appearance.
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  • 17
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    Why are oceanic arc basalts Ca-rich and Ni-poor? Insights from olivine-hosted melt inclusions from Kibblewhite Volcano in the Kermadec arc (2024)
    Elsevier
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    Publication Date: 2024-07-02
    Description: Highlights • Ankaramites are Ca-rich and Ni-poor porphyritic basalts that are common in oceanic arcs. • Melt inclusions from Kibblewhite Volcano show similar compositions to ankaramites. • Ankaramite is a primary magma component in oceanic arcs. • Interaction between melt and mantle can produce ankaramitic melts. • Harzburgite formed by melt-mantle interactions is the source of high-Mg andesites. Abstract Ankaramites, which are clinopyroxene-rich basalts with primitive whole-rock compositions (Mg# 〉65), are common in oceanic arcs and are characterized by high whole-rock CaO/Al2O3 (〉1.0) ratios and olivine crystals with anomalously low nickel contents (〈0.2 wt% NiO). These geochemical characteristics cannot be explained by the melting of ordinary mantle peridotite. However, their origin is critical for understanding the formation of primary magmas in oceanic arcs. Here, we investigated olivine-hosted melt inclusions (MIs) from ankaramites and magnesian andesites of the Kibblewhite Volcano in the Kermadec arc. The MIs from the ankaramites have similar major and trace element characteristics to the host rocks, indicating that the ankaramites did not result from an accumulation of mafic minerals but rather represent the primary magma in the Kibblewhite Volcano. The MIs from the magnesian andesites were hosted in forsteritic olivine xenocrysts with a wide range of NiO contents (Fo90–92; 0.13–0.39 wt% NiO) and have similar major element compositions to the ankaramites but exhibit a wide range of CaO/Al2O3 (0.85–1.54). The trace element characteristics of the MIs from the magnesian andesites do not match those of the host rocks, indicating that they are not primary melts of the magnesian andesites but primitive basaltic melts generated before the magnesian andesites formed. Interestingly, the CaO/Al2O3 ratio of MIs from the magnesian andesites was negatively correlated with the NiO content of their host olivines. This correlation suggests that the composition of the primary basaltic magmas of the Kibblewhite Volcano changed continuously from peridotite-derived to ankaramitic. This correlation could not be explained by grain-scale process, crustal anatexis, or contribution of slab-derived carbonate-rich fluids. Instead, we propose that this correlation can be explained by the interaction of the ascending primary basaltic melts with the lithospheric mantle. During melt-mantle interaction, the assimilation of clinopyroxene and fractionation of olivine and orthopyroxene caused the CaO/Al2O3 ratio to increase in the melt and the Ni content to decrease. Furthermore, because the magnesian andesites have low CaO/Al2O3 ratios and could be derived from a clinopyroxene-poor mantle lithology, the interaction between the melt and mantle may also be closely related to the origin of the magnesian andesites at Kibblewhite Volcano. This interpretation provides a new perspective on the origin of the oceanic arc ankaramites and why primary andesitic and basaltic magmas coexist in the Kibblewhite Volcano.
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  • 18
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    Understanding the links between volcanic systems and epithermal ore formation: A case study from Conical Seamount, Papua New Guinea (2024)
    Elsevier
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    Publication Date: 2024-07-02
    Description: Highlights • Alkaline magmas of the TLTF island chain result from a subduction-modified mantle source and two-stage partial melting. • The role of mantle source and parental melt composition for high Cu-Au mineral potentials is important but limited. • A shallow crustal magma reservoir is key for epithermal ore formation. Abstract The Tabar-Lihir-Tanga-Feni (TLTF) island chain in northeastern Papua New Guinea formed by tectonic and alkaline to shoshonitic magmatic activity since the Pliocene. Several volcanic centers are Cusingle bondAu mineralized including the world-class Ladolam Au deposit and Conical Seamount south of Lihir. The latter has been recognized as a juvenile analogue to the Ladolam deposit located on-shore. Whereas the mineralization at Conical Seamount is reasonably well studied, the specific magmatic processes that promote epithermal mineralization at this seamount but not at others are poorly understood. Here, we present new petrological and geochemical data from Conical Seamount, and compare them with those from the barren (unmineralized) Edison, Tubaf and New World seamounts nearby. We focus on whole rock compositions and major and trace element analysis of melt inclusions and minerals including clinopyroxene, sulfide and magnetite. We combine our observations with modelled constraints on mantle source composition and partial melting as well as magma evolution. A first-stage melting leaves a residual mantle source enriched in Au. Second-stage melting of a previously subduction-metasomatized mantle generally promotes the transfer and concentration of metals and volatiles in the ascending melts. These magmas are unlikely to control ore formation as all seamounts show evidence for similar mantle sources and parental melt composition. However, the presence of a shallow crustal magma chamber is unique to Conical Seamount. It is characterized by frequent melt replenishments and extensive magma fractionation leading to sulfide and magmatic volatile saturation. These specific magma chamber processes lead to the pre-enrichment of the magma in chalcophile elements including Au, while sulfide saturation coeval with magmatic volatile exsolution provide the way for an effective Au transfer from the magmatic to the epithermal system.
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  • 19
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    Global Nitrous Oxide Budget 1980–2020 (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-07-02
    Description: Nitrous oxide (N2O) is a long-lived potent greenhouse gas and stratospheric ozone-depleting substance, which has been accumulating in the atmosphere since the pre-industrial period. The mole fraction of atmospheric N2O has increased by nearly 25 % from 270 parts per billion (ppb) in 1750 to 336 ppb in 2022, with the fastest annual growth rate since 1980 of more than 1.3 ppb yr-1 in both 2020 and 2021. As a core component of our global greenhouse gas assessments coordinated by the Global Carbon Project (GCP), we present a global N2O budget that incorporates both natural and anthropogenic sources and sinks, and accounts for the interactions between nitrogen additions and the biochemical processes that control N2O emissions. We use Bottom-Up (BU: inventory, statistical extrapolation of flux measurements, process-based land and ocean modelling) and Top-Down (TD: atmospheric measurement-based inversion) approaches. We provide a comprehensive quantification of global N2O sources and sinks in 21 natural and anthropogenic categories in 18 regions between 1980 and 2020. We estimate that total annual anthropogenic N2O emissions increased 40 % (or 1.9 Tg N yr-1) in the past four decades (1980–2020). Direct agricultural emissions in 2020, 3.9 Tg N yr−1 (best estimate) represent the large majority of anthropogenic emissions, followed by other direct anthropogenic sources (including ‘Fossil fuel and industry’, ‘Waste and wastewater’, and ‘Biomass burning’ (2.1 Tg N yr−1), and indirect anthropogenic sources (1.3 Tg N yr−1). For the year 2020, our best estimate of total BU emissions for natural and anthropogenic sources was 18.3 (lower-upper bounds: 10.5–27.0) Tg N yr-1, close to our TD estimate of 17.0 (16.6–17.4) Tg N yr-1. For the period 2010–2019, the annual BU decadal-average emissions for natural plus anthropogenic sources were 18.1 (10.4–25.9) Tg N yr-1 and TD emissions were 17.4 (15.8–19.20 Tg N yr-1. The once top emitter Europe has reduced its emissions since the 1980s by 31 % while those of emerging economies have grown, making China the top emitter since the 2010s. The observed atmospheric N2O concentrations in recent years have exceeded projected levels under all scenarios in the Coupled Model Intercomparison Project Phase 6 (CMIP6), underscoring the urgency to reduce anthropogenic N2O emissions. To evaluate mitigation efforts and contribute to the Global Stocktake of the United Nations Framework Convention on Climate Change, we propose establishing a global network for monitoring and modeling N2O from the surface through the stratosphere. The data presented in this work can be downloaded from https://doi.org/10.18160/RQ8P-2Z4R (Tian et al. 2023).
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    Patterns and dynamics of sedimentation and biogeochemical processes in the Skagerrak (2024)
    Details
    Publication Date: 2024-07-02
    Description: The North Sea represents a major sink for atmospheric carbon dioxide (CO2) from anthropogenic emissions. However, the North Sea sediment and carbon cycles have been heavily affected by human activities during the last century. In particular, frequent resuspension of sedimentary particulate organic carbon (POC) by bottom trawling, dredging or wind farm constructions might reduce POC burial and, consequently, reduce the CO2 sequestration potential of the North Sea. The Skagerrak serves as the largest depocenter for sediments and POC in the North Sea. Hence, Skagerrak deposits provide a historical record of how the North Sea ecosystem has changed over time. This thesis revisits sedimentation and biogeochemical processes in the Skagerrak based on a combination of solid phase and porewater geochemistry, in-situ measurements and modeling. Highly resolved temporal and spatial data are used to better characterize the benthic sediment, POC and biogenic silica (bSi) cycles in the Skagerrak and to track the impact of human and natural processes in the North Sea over the past ~100 years. A major finding of this thesis reveals that average sedimentation rates and POC burial fluxes substantially decreased from before to after the year 1963 in the Skagerrak. Possible explanations involve a shift in the North Sea circulation pattern and increasing POC settling in other depocenters of the North Sea, such as the Wadden Sea. Hence, deposition rates in the Skagerrak are likely dominated by these processes rather than by the effect of sediment resuspension caused by human activities on deposition rates in the Skagerrak. In order to assess the spatial variability of sedimentation processes in the Skagerrak, a machine learning model is used to upscale compiled datasets to areawide spatial distributions of porosities, mass accumulation rates (MAR) and lead-210 (210Pb) rain rates in the Skagerrak. The spatial distributions reveal areas of elevated 210Pb rain rates and MAR at intermediate water depths following the shape of the general water circulation pattern. A tentative North Sea sediment budget including the updated MAR estimate highlights the Skagerrak as the primary sink for material in the North Sea. The benthic cycles of POC and bSi show that roughly 50 % of the POC and bSi raining onto the seafloor are recycled during early diagenesis and reintroduced to bottom waters. The other half is permanently buried in the sediment. In a global context, comparably high POC and bSi burial efficiencies as well as low sedimentary bSi:POC ratios reflect the influence of the large lateral sediment input from the North Sea. The 210Pb and bSi rain rates are further used to estimate the contributions of locally produced and laterally transported POC to the total sedimentary POC pool. They are included in a compilation of different approaches, which show that 19±6 % of the deposited POC are derived from local primary production, whereas 81±6 % are transported laterally into the Skagerrak. The results of this thesis extend our knowledge of sedimentation and biogeochemical processes in the Skagerrak under changing environmental conditions. However, further work is recommended for a detailed understanding of how the Skagerrak and the North Sea have been affected by human activities. In particular, large-scale and temporally resolved particle transport models and provenance studies could help to identify the major drivers behind the decline in sedimentation rates and POC burial in the Skagerrak.
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  • 21
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    Risk governance (2024)
    In:  Elgar Encyclopedia of Interdisciplinarity and Transdisciplinarity
    Details
    Publication Date: 2024-07-02
    Description: The IRGC risk governance framework refers to an integrated concept on how to deal with a variety of physical, environmental and social risks characterized by complex, uncertain and ambiguous impacts. The framework has been informed by interdisciplinary research drawing from sociological and psychological research, including investigations about regulatory styles, institutional regimes and public participation. The notion of governance pertains to the many ways in which all relevant actors, individuals and institutions, public and private, deal with interventions that impact nature and human societies. It includes formal institutions and regimes as well as informal arrangements for including stakeholders and the public at large.
    Language: English
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  • 22
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    The many faces of uncertainty: a comment to Lofstedt and Bouder (2024)
    In:  Journal of risk research
    Details
    Publication Date: 2024-07-02
    Description: Risk and uncertainty communication of often directed towards addressing the relevance and meaning of probability distributions over negative outcomes and statistical confidence intervals. As much as a professional handling of complex mathematical operations is needed, this will cover only a fraction of what uncertainty communication needs to addres. In those cases where estimates of uncertainty come close to educated guesses, simple beliefs or even total ignorance, other important cues may be more important than formal expertise in risk assessments. These include trust in the risk management agencies or other influential actors, personal experience, indigenous or community-based knowledge, common sense and argumentative or persuasive power. Once the full range of uncertainty is in the focus of risk managemem and communication institutions, an interdisciplinary, inclusive and demand-driven communication strategy needs to be developed. As recommended in the paper by Lofstedt and Bouder, such a targeted approach to risk and uncertainty communication requires interdisciplinary expertise, competence in the social and natural sciences, and practical experience in designing public discourses.
    Language: English
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  • 23
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    Community resilience through bottom–up participation: when civil society drives urban transformation processes (2024)
    In:  Community Development Journal
    Details
    Publication Date: 2024-07-02
    Description: In recent years, bottom–up civil society initiatives have advanced urban transformation processes in Berlin. Following previous research suggesting that bottom–up participation could have a positive impact on community resilience (CR), we analyse the impact of engagement on Berlin–based civil society initiatives. Whilst a positive effect on resilience can be found, we identify governance processes that would be necessary to enable the full potential of bottom–up participation for CR. Resilience, understood as the capacity of a community to thrive in times of change and uncertainty, is becoming increasingly important for the functioning of (urban) communities; hence, finding ways of strengthening it is deemed necessary.
    Language: English
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  • 24
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    Curiosity-driven research (2024)
    In:  Elgar Encyclopedia of Interdisciplinarity and Transdisciplinarity
    Details
    Publication Date: 2024-07-02
    Description: In the light of the major global crises such as pandemics, war, climate change and inequality, scientific research faces new challenges and targets. Scientific studies are supposed to provide background knowledge, to facilitate the desired transformation towards a sustainable future and to offer assistance for resolving complex problems that accompany societies in transition. Concepts such as transformative, transdisciplinary or co-creative research elucidate the direction in which scientific research finds its new role(s). Based on the discussion of these concepts and their different roots, the entry analyzes a new modular concept for a transdisciplinary scientific approach combining and integrating classic curiosity-driven research with goal oriented (advocacy) knowledge and catalytic, process-oriented expertise. In particular it emphasizes the role and function of curiosity-driven research for a comprehensive design of transdisciplinarity and transformative research. There is no doubt that society needs better transformative knowledge to facilitate actions towards sustainability but such knowledge rests on evidence-based insights from disciplinary and interdisciplinary research efforts. The entry provides an orientation of how this classic research outcomes can effectively be integrated into a transdisciplinary context.
    Language: English
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  • 25
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    Towards a public policy of cities and human settlements in the 21st century (2024)
    In:  npj urban sustainability
    Details
    Publication Date: 2024-07-02
    Description: Cities and other human settlements are major contributors to climate change and are highly vulnerable to its impacts. They are also uniquely positioned to reduce greenhouse gas emissions and lead adaptation efforts. These compound challenges and opportunities require a comprehensive perspective on the public policy of human settlements. Drawing on core literature that has driven debate around cities and climate over recent decades, we put forward a set of boundary objects that can be applied to connect the knowledge of epistemic communities and support an integrated urbanism. We then use these boundary objects to develop the Goals-Intervention-Stakeholder-Enablers (GISE) framework for a public policy of human settlements that is both place-specific and provides insights and tools useful for climate action in cities and other human settlements worldwide. Using examples from Berlin, we apply this framework to show that climate mitigation and adaptation, public health, and well-being goals are closely linked and mutually supportive when a comprehensive approach to urban public policy is applied. © The Author(s) 2024.
    Language: English
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  • 26
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    Bergordnung für den Emmler (2024)
    Details
    Publication Date: 2024-07-01
    Description: Nach der Übernahme des Territoriums des Klosters Grünhain durch die Wettiner im Jahr 1536 und der Verwaltungsreform durch Kurfürst Moritz wurde für den Bergbau am Emmler eine neue Bergordnung notwendig. Diese erließ der Oberhauptmann des (erz)gebirgischen Kreises, Heinrich von Gersdorff, in seiner Amtszeit zwischen 1547 und 1554.
    Description: source
    Keywords: Kurfürst Moritz von Sachsen ; Heinrich von Gersdorf ; Kloster Grünhain ; Annaberg ; Eisenerzbergbau ; Bergordnung
    Language: German
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    Plume-influenced mid-ocean ridges -Insights into the geodynamics from the Foundation segment on the Pacific-Antarctic Ridge (2024)
    Frontiers
    Details
    Publication Date: 2024-07-01
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  • 28
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    BELUGA: An Integrated Marine Multi-Platform Infrastructure and Near Real-Time Ocean Data Visualization Tool (2023)
    Details
    Publication Date: 2024-07-01
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 29
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    Tellurium Transport and Enrichment in Volcanogenic Massive Sulfide Deposits: Numerical Simulations of Vent Fluids and Comparison to Modern Sea-Floor Sulfides (2024)
    Society of Economic Geologists (SEG)
    Details
    Publication Date: 2024-07-01
    Description: Volcanogenic massive sulfide deposits may represent a significant future source of Te, which is a critical element important for the green energy transition. Tellurium is enriched in these settings by up to 10,000 times over its crustal abundance, indicating that fluids in sea-floor hydrothermal systems may transport and precipitate Te. The major element composition of these hydrothermal fluids is controlled by fluid-rock interaction and is well documented based on experimental, modeling, and natural studies; however, controls on Te mobility are still unknown. To better understand Te enrichment in this deposit type, numerical simulations of the mafic-hosted Vienna Woods and the felsic-hosted Fenway sea-floor vents in the Manus basin were performed to predict Te mobility in modern sea-floor hydrothermal vent fluids and Te deposition during sulfide formation. These simulations demonstrate that the mobility of Te in sea-floor hydrothermal systems is primarily controlled by fluid redox and temperature. Tellurium mobility is low in reduced hydrothermal fluids, whereas mobility of this metal is high at oxidized conditions at temperatures above 250°C. Numerical simulations of the reduced vent fluids of the mafic-hosted Vienna Woods site at the back-arc spreading center in the Manus basin yielded Te concentrations as low as 0.2 ppt. In contrast, the more oxidized model fluids of the felsic-hosted Fenway site located on Pual Ridge in the eastern Manus basin contain 50 ppt Te. The models suggest that Te enrichment in these systems reflects rock-buffer control on oxygen fugacity, rather than an enriched source of Te. In fact, the mafic volcanic rocks probably contain more Te than felsic volcanic rocks. The association of elevated Te contents in the felsic-hosted Fenway system likely reflects magmatic volatile input resulting in lower pH and higher Eh of the fluids. More generally, analysis of sulfide samples collected from modern sea-floor vent sites confirms that redox buffering by the host rocks is a first-order control on Te mobility in hydrothermal fluids. The Te content of sulfides from sea-floor hydrothermal vents hosted by basalt-dominated host rocks is generally lower than those of sulfides from vents located in felsic volcanic successions. Literature review suggests that this relationship also holds true for volcanogenic massive sulfides hosted in ancient volcanic successions. Results from reactive transport simulations further suggest that Te deposition during sulfide formation is primarily temperature controlled. Modeling shows that tellurium minerals are coprecipitated with other sulfides at high temperatures (275°–350°C), whereas Te deposition is distinctly lower at intermediate (150°–275°C) and low temperatures (100°–150°C). These predictions agree with geochemical analyses of sea-floor sulfides as Te broadly correlates positively with Cu and Au enrichment in felsic-hosted systems. The findings of this study provide an important baseline for future studies on the behavior of Te in hydrothermal systems and the processes controlling enrichment of this critical mineral in polymetallic sulfide ores.
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  • 30
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    4. Wochenbericht M201 VebVolc (2024)
    GEOMAR Helmholtz Centre for Ocean Research
    Details
    Publication Date: 2024-07-01
    Description: FS METEOR Expedition M201 VebVolc, 09.06. – 18.07.2024 | Reykjavik – Praia da Vitoria
    Type: Report , NonPeerReviewed
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    Report on modifications of ocean carbon cycle feedbacks under ocean alkalinization (2022)
    OceanNETs
    Details
    Publication Date: 2024-07-01
    Description: Ocean Alkalinization deliberately modifies the chemistry of the surface ocean to enhance the uptake of atmospheric CO2. Here we quantify, using idealized Earth system model (ESM) simulations, changes in carbon cycle feedbacks and in the seasonal cycle of the surface ocean carbonate system due to ocean alkalinization. We find that both, carbon-concentration and carbon climate feedback, are enhanced due to the increased sensitivity of the carbonate system to changes in atmospheric CO2 and changes in temperature. While the temperature effect, which decreases ocean carbon uptake, remains small in our model, the carbon concentration feedback enhances the uptake of carbon due to alkalinization by more than 20%. The seasonal cycle of air-sea CO2 fluxes is strongly enhanced due to an increased buffer capacity in an alkalinized ocean. This is independent of the seasonal cycle of pCO2, which is only slightly enhanced. The most significant change in the seasonality of the surface ocean carbonate system is an increased seasonal cycle of the aragonite saturation state, which has the potential to adversely affect ecosystem health.
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  • 32
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    Influence of Hydrodynamics on the Composition and Reactivity of Particulate Organic Matter in a Large River Influenced Ocean Margin (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-07-01
    Description: Marginal seas influenced by large rivers are characterized by complex hydrodynamic and organic matter cycling processes. However, the impacts of hydrodynamics on the composition and reactivity of particulate organic matter (POM) remain unclear. Here we conducted a comprehensive study on the bulk, molecular and biological properties of suspended POM in the Changjiang Estuary and adjacent area subjected to strong currents, eddies as well as typhoons during spring and autumn. D/L‐enantiomers of particulate amino acids (PAA) were analyzed to evaluate the bioreactivity of POM and quantify bacterial‐derived organic carbon. We found that POM bioavailability as indicated by carbon‐normalized yields of PAA (PAA‐C%) reflected the ecosystem productivity. Relatively high PAA‐C% values (20−35%) were observed in productive areas influenced by Changjiang River plume, cyclonic eddies and typhoons, likely related to the enhanced nutrient availability arising from hydrodynamic processes. In contrast, the oligotrophic Taiwan Warm Current‐influenced regions featured relatively low POM bioavailability (PAA‐C% 〈 10%) despite typhoons facilitating water mixing. The PAA‐C% values showed a significant positive correlation with extracellular enzyme activity, indicating that bioavailable POM can rapidly stimulate heterotrophic transformation. Hot spots of elevated bioavailable POM showed high contributions of bacterial organic carbon. A large portion (∼2/3) of bacterial organic carbon was present in the form of bacterial detritus, suggesting that patches of these biological hot spots represent important sites of carbon sequestration. Together, our findings indicate that fresh POM production is largely controlled by nutrient supply driven by hydrodynamic processes, with important implications for carbon sequestration in the dynamic ocean margins. Plain Language Summary Marginal seas are subject to complex hydrodynamic processes and play an important role in carbon sequestration. Disentangling the linkages between hydrodynamics and organic carbon reactivity and composition is crucial to understanding the regional carbon cycle. Here we collected suspended particulate organic matter (POM) in the Changjiang Estuary and adjacent coastal areas. Based on the biomarker D/L‐amino acids, we assessed the bioavailability of POM and quantified the organic carbon originating from bacteria. We found that high bioactivity of POM occurred in productive Changjiang River plume, cyclonic eddy, and typhoon influenced areas. These hydrodynamic processes appear to increase nutrient availability, therefore promoting phytoplankton growth. Bioavailable POM can rapidly stimulate heterotrophic activity and facilitate the transformation of algal‐derived organic carbon to bacterial detritus, thus contributing to carbon sequestration. Our findings suggest that the production of bioavailable POM is largely controlled by hydrodynamically driven nutrient supply. Key Points We use D/L‐amino acids to assess the bioreactivity and bacterial origins of particulate organic matter (POM) in the dynamic Changjiang Estuary and adjacent area High bioavailability of POM occurs in productive regions affected by Changjiang River plume, cyclonic eddies and typhoons Hot spots of bioavailable POM represent important sites for carbon sequestration
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    First release of the Pelagic Size Structure database: global datasets of marine size spectra obtained from plankton imaging devices (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-07-01
    Description: In marine ecosystems, most physiological, ecological, or physical processes are size dependent. These include metabolic rates, the uptake of carbon and other nutrients, swimming and sinking velocities, and trophic interactions, which eventually determine the stocks of commercial species, as well as biogeochemical cycles and carbon sequestration. As such, broad-scale observations of plankton size distribution are important indicators of the general functioning and state of pelagic ecosystems under anthropogenic pressures. Here, we present the first global datasets of the Pelagic Size Structure database (PSSdb), generated from plankton imaging devices. This release includes the bulk particle normalized biovolume size spectrum (NBSS) and the bulk particle size distribution (PSD), along with their related parameters (slope, intercept, and R2) measured within the epipelagic layer (0–200 m) by three imaging sensors: the Imaging FlowCytobot (IFCB), the Underwater Vision Profiler (UVP), and benchtop scanners. Collectively, these instruments effectively image organisms and detrital material in the 7–10 000 µm size range. A total of 92 472 IFCB samples, 3068 UVP profiles, and 2411 scans passed our quality control and were standardized to produce consistent instrument-specific size spectra averaged to 1° × 1° latitude and longitude and by year and month. Our instrument-specific datasets span most major ocean basins, except for the IFCB datasets we have ingested, which were exclusively collected in northern latitudes, and cover decadal time periods (2013–2022 for IFCB, 2008–2021 for UVP, and 1996–2022 for scanners), allowing for a further assessment of the pelagic size spectrum in space and time. The datasets that constitute PSSdb's first release are available at https://doi.org/10.5281/zenodo.11050013 (Dugenne et al., 2024b). In addition, future updates to these data products can be accessed at https://doi.org/10.5281/zenodo.7998799.
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    Temporal Variability of Ventilation in the Eurasian Arctic Ocean (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-07-01
    Description: The Arctic Ocean plays an important role in the regulation of the earth's climate system, for instance by storing large amounts of carbon dioxide within its interior. It also plays a critical role in the global thermohaline circulation, transporting water entering from the Atlantic Ocean to the interior and initializing the southward transport of deep waters. Currently, the Arctic Ocean is undergoing rapid changes due to climate warming. The resulting consequences on ventilation patterns, however, are scarce. In this study we present transient tracer (CFC-12 and SF6) measurements, in conjunction with dissolved oxygen concentrations, to asses ventilation and circulation changes in the Eurasian Arctic Ocean over three decades (1991–2021). We constrained transit time distributions of water masses in different areas and quantified temporal variability in ventilation. Specifically, mean ages of intermediate water layers in the Eurasian Arctic Ocean were evaluated, revealing a decrease in ventilation in each of the designated areas from 2005 to 2021. This intermediate layer (250–1,500 m) is dominated by Atlantic Water entering from the Nordic Seas. We also identify a variability in ventilation during the observation period in most regions, as the data from 1991 shows mean ages comparable to those from 2021. Only in the northern Amundsen Basin, where the Arctic Ocean Boundary Current is present at intermediate depths, the ventilation in 1991 is congruent to the one in 2005, increasing thereafter until 2021. This suggests a reduced ventilation and decrease in the strength of the Boundary Current during the last 16 years. Key Points Temporal variability of ventilation in the Eurasian Arctic Ocean during the past 30 years is estimated by observations of transient tracers We found a slow down of the ventilation between 2005 and 2021 in the intermediate waters Evidence of multidecadal variability of ventilation in the intermediate waters of the Eurasian Arctic Ocean is present Plain Language Summary The Eurasian Arctic Ocean, the region of the Arctic Ocean connected to the European and Asian continents, is an important pathway for recently ventilated water from the Nordic Seas. These waters are exported back to the North Atlantic following their travel through the Arctic Ocean. Ventilation describes the process of surface waters being transported into the interior ocean due to increasing density, which affects the underlying water masses. In this study we investigate how the ventilation patterns have evolved in the Eurasian Arctic Ocean over the past three decades, using transient tracer (CFC-12 and SF6) measurements. We observed a significant change in the intermediate layer (250–1,500 m) with older waters found in measurements in 1991 and 2021 compared to 2005 and 2015. Moreover, our data suggest a slowdown in ventilation throughout the three decades in the northern Amundsen Basin, implying a decrease in the circulation time-scale of the Arctic Ocean Boundary Current over the past 16 years. This has potentially important implications for the transport of, for example, heat, salt or oxygen from the Atlantic Ocean around the Arctic Ocean, and back.
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  • 35
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    Provenance of clay-sized detrital sediments in the North Sea and the Skagerrak region based on radiogenic Nd-Sr-Hf isotopes and clay mineral compositions: Assessing the impact of coastal and seabed erosion (2024)
    Frontiers
    Details
    Publication Date: 2024-07-01
    Description: The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition centre for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood.To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured.The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes related to this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea.With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea.
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    Assessing the availability of trace metals and rare earth elements in deep ocean waters of the Clarion-Clipperton Zone, NE Pacific: Application of an in situ DGT passive sampling method (2022)
    Elsevier
    Details
    Publication Date: 2024-07-01
    Description: Highlights • First successful in situ DGT application in the deep ocean. • DGT-lability of dissolved (〈0.2 μm) Cu, Ni, Cd, Mn, As, V, REY differs depending on chemical speciation. • REY in deep ocean water can be almost quantitatively assessed with DGT. • Low Cu availability reflects dominating organic speciation. Abstract Geochemical behaviour and bio-availability of trace metals are closely related to their physical fractionation and chemical speciation. The DGT speciation technique allows the challenging assessment of labile concentrations of Mn, Cd, Cu, Ni, V, As, and REY in ocean waters. In this first deep-water in situ study of DGT-lability, we demonstrate the approach in bottom waters of the Clarion-Clipperton Zone in the central NE Pacific. In the dissolved fraction (〈0.2 μm), 70% to 100% of Cd, Ni, V, and REY, but only 25% of Cu and less than 50% of As were determined, reflecting their prevailing dominance of organic vs. inorganic complexation. This study demonstrates the applicability and sensitivity of DGT-passive samplers for trace metals as a suitable technique in monitoring of anthropogenic activities, such as deep seabed mining, as well as for natural process studies in abyssal environments.
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    Modulation of Equatorial Currents and Tropical Instability Waves During the 2021 Atlantic Niño (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-06-30
    Description: In the boreal summer of 2021, the equatorial Atlantic experienced the strongest warm event, that is, Atlantic Niño, since the beginning of satellite observations in the 1970s. Such events have far‐reaching impacts on large‐scale wind patterns and rainfall over the surrounding continents. Yet, developing a paradigm of how Atlantic Niño interacts with the upper‐ocean currents and intraseasonal waves remains elusive. Here we show that the equatorial Kelvin wave associated with the onset of the 2021 Atlantic Niño modulated both the background flow and the eddy flux of the equatorial upper‐ocean circulation, causing an extremely weak and delayed tropical instability wave (TIW) season. TIW‐induced variations of sea surface temperature (SST), sea surface salinity, sea surface height, and eddy temperature advection were exceptionally weak during May to July, the climatological peak of TIW activity, but rebounded in August when higher than normal variability was observed. Moored velocity data at 23°W show that during the peak of the 2021 Atlantic Niño from June to August, the Equatorial Undercurrent was deeper and stronger than usual. An anomalously weak eddy momentum flux strongly suppressed barotropic energy conversion north of the equator from May to July, likely contributing to low TIW activity. Reduced baroclinic energy conversion also might have played a role, as the meridional gradient of SST was sharply reduced during the Atlantic Niño. Despite extremely weak TIW velocities, modest intraseasonal variability of chlorophyll‐a (Chl‐ a ) was observed during the Atlantic Niño, due to pronounced meridional Chl‐ a gradients that partly compensated for the weak TIWs. Plain Language Summary Every few years the eastern equatorial Atlantic Ocean is significantly warmer than usual during boreal summer. Such warm events are referred to as Atlantic Niño events, and share similarities with El Niño events in the Pacific. In 2021, the strongest Atlantic Niño in at least four decades was observed in the equatorial Atlantic. This study is the first that investigates the complex interaction between Atlantic Niño, tropical Atlantic upper‐ocean currents, and equatorial waves based on various observational data sets. We show that the developing 2021 Atlantic Niño weakened both the background flow and the variability of near‐surface currents in May, which in turn largely reduced the strength of intraseasonal (20–50 days) waves that are usually generated by instability of the upper‐ocean zonal currents. As a consequence, the cooling effect that these waves usually have north of the equator and the warming effect along the equator vanished from May to July 2021. Interestingly, variability of chlorophyll concentration was enhanced, suggesting that enhanced meridional chlorophyll gradients compensated for reduced wave activity. Key Points The developing 2021 Atlantic Niño led to weaker equatorial surface currents and reduced vertical shear of upper‐ocean horizontal velocity Strong reduction of the surface flow, eddy flux, and meridional temperature gradient in May caused extremely weak and delayed tropical instability wave (TIW) season Reduced meridional TIW advection contributed to sharpen the north equatorial Chl‐ a front resulting in modest intraseasonal Chl‐ a variability
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    Divergence between sea urchins and their microbiota following speciation (2024)
    Springer
    Details
    Publication Date: 2024-06-28
    Description: Animals have a deep evolutionary relationship with microbial symbionts, such that individual microbes or an entire microbial community can diverge alongside the host. Here, we explore these host-microbe relationships in Echinometra, a sea urchin genus that speciated with the Isthmus of Panama and throughout the Indo-West Pacific. We find that the eggs from five Echinometra species generally associate with a species-specific bacterial community and that the relatedness of these communities is largely congruent with host phylogeny. Microbiome divergence per million years was higher in more recent speciation events than in older ones. We, however, did not find any bacterial groups that displayed co-phylogeny with Echinometra. Together, these findings suggest that the evolutionary relationship between Echinometra and their microbiota operates at the community level. We find no evidence suggesting that the associated microbiota is the evolutionary driver of Echinometra speciation. Instead, divergence between Echinometra and their microbiota is likely the byproduct of ecological, geographic, and reproductive isolations.
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    The ocean-continent transition in the Western Central Red Sea (2023)
    Elsevier
    Details
    Publication Date: 2024-06-28
    Description: The Red Sea is an important example of a continental rift transitioning slowly to an oceanic basin. However, structures that can inform us of how that transition occurred have been poorly reported because deep seismic reflection data capable of imaging basement under the rift sediments are generally lacking publicly. Three lines of multichannel seismic reflection data have recently been published revealing structures on the Nubian side of the central part of the basin. In this study, we reassess these data in the light of recent studies of the central Red Sea. Over continental crust, the data reveal reflection sequences likely due to strata at or near the base of the evaporites, in two cases with varied dips suggesting the presence of syn-rift growth stratigraphy. Almost all of those reflections dip downwards towards the rift axis, not away as would be expected from tilted fault blocks of bookshelf faulting types. That observation, and low relief of basement, confirm inferences made earlier based on gravity anomalies that this part of the Red Sea lacks large-relief fault escarpments and is most likely a syn-rift sag basin. In the transition to oceanic crust, an abnormally broad magnetic anomaly of estimated Chron 5 age is found not to be associated with structures such as sills, so it likely arises from deeper sources. One of the seismic lines traverses a ridge in Bouguer gravity anomalies that runs across the axis. This feature has previously been interpreted as a volcanic ridge similar to those observed at other ultra-slow spreading ridges. The seismic data reveal diffuse basement reflections and confirm that the record immediately above basement lacks reflections typical of sedimentary strata. Both observations are consistent with the presence of oceanic crust. Modelling of gravity anomalies suggests the ridge is likely underlain by igneous intrusive rocks displacing mantle rocks, as expected for a volcanic ridge. The seismic data, combined with recently updated multibeam and high-resolution sparker seismic results, further suggest how the evaporite movements have been modulated by basement topography. These results add to our knowledge of the evaporite movements and continent-ocean transition structures in the central Red Sea.
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    Cross-shelf transport of high chlorophyll-a coastal waters by frontal eddies in the south of Java sea (2024)
    Elsevier
    Details
    Publication Date: 2024-06-28
    Description: Highlights: • A cyclonic frontal eddy emerged near the South Java Coast (SJC) in 2019. • The cyclonic eddy induces filaments of Chl-a, cold water, and nutrients. • Anti-cyclonic eddies distribute the filaments further offshore. • The role of wind can't be ignored in distributing filaments in the SJC. • We propose a three-stage mechanism for Chl-a distribution in the offshore SJC. Intense mesoscale eddy activity has been observed off the southern Java coast (SJC), yet its impact on local ecosystems remains largely unknown. To investigate this, we examined remotely sensed altimetry, chlorophyll-a (Chl-a), and sea surface temperature (SST) data, focusing on their response to eddies in the region. Our eddy detection and tracking analysis revealed a unique cyclonic frontal eddy near the SJC coast and a large anticyclonic eddy offshore, active from July to September 2019. The cyclonic frontal eddy induced water transport through eddy filaments, upwelled subsurface cold water, and enhanced Chl-a concentrations by horizontally entraining Chl-a-rich shelf water offshore. The anticyclonic eddy then contributed to further distributing this enriched water southward. The mean cross-shelf transport associated with the frontal eddy was estimated at 1.80–2.33 Sv offshore, exporting approximately 1.87–2.40 × 103 tons of Chl-a to the Indian Ocean during its lifetime. Additionally, the spatial cross-correlation analysis of zonal and meridional wind stress with Chl-a revealed relatively high correlation values (0.6–1) and short lag times (〈5 days) in offshore areas, indicating that the role of wind in the Chl-a advection cannot be ignored. We propose a three-stage mechanism to explain the presence of high Chl-a offshore:1) Wind-driven upwelling intensifies coastal nutrients, elevating Chl-a concentrations in coastal waters, 2) Frontal cyclonic eddy facilitates the retention and offshore export of these upwelling-enriched waters. and 3) Anticyclonic eddy advects these nutrient-rich waters further south. The combination of enhanced coastal upwelling and eddies can explain nutrient-rich coastal waters in offshore regions
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    Dual clumped isotopes from Mid-Eocene bivalve shell reveal a hot and summer wet climate of the Paris Basin (2024)
    Nature Research
    Details
    Publication Date: 2024-06-28
    Description: Accurate reconstruction of seasonal atmospheric patterns of the past is essential for reliable prediction of how climate will evolve due to anthropogenic CO2 forcing. The Eocene ‘hot house’ climate, as the warmest epoch during the Cenozoic, is considered as a potential analogue for ‘high-CO2’ future climate scenarios. In this context, the reconstruction of variations in seasonality are as important as changes in mean annual conditions. Here we combine stable oxygen (δ18O) and dual clumped isotope (Δ47 + Δ48) measurements of a bivalve shell to determine sub-annual variations in sea surface temperatures and oceanic freshening in the Paris Basin during the Mid-Eocene Climate Optimum, 40 million years ago. Our reconstruction indicates to high mean annual temperatures with a small seasonal amplitude (33.3 °C ± 4.4 °C) and an enhanced fresh water input during the summer period. Our results implying a substantially warmer climate state with different hydrological conditions for Western Europe during the Eocene than previously suggested by proxy data or climate modelling.
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    Seismic evidence for possible entrainment of rising plumes by subducting slab induced flow in three subduction zones surrounding the Caribbean Plate (2024)
    Elsevier
    Details
    Publication Date: 2024-06-28
    Description: The dynamic processes associated with subducting tectonic plates and rising plumes of hot material are typically treated separately in dynamical models and seismological studies. However, various types of observations and related models indicate these processes overlap spatially. Here we use precursors to PP and SS reflecting off mantle transition zone discontinuities to map deflections of these discontinuities near three subduction zones surrounding the Caribbean Plate: 1) Lesser Antilles, 2) Middle America and 3) northern South American subduction zones. In all three regions slow seismic anomalies are present behind the sinking slab within the transition zone in tomographic images. Using array methods, we identify precursors and verify their in-plane propagation for MW ≥ 5.8 events occurring between the years 2000 and 2020 by generating a large number of source receiver combinations with reflection points in the area, including crossing ray paths. The measured time lag between PP/SS arrivals and their corresponding precursors on robust stacks are used to measure the depth of the mantle transition zone discontinuities. In all three areas we find evidence for upward deflection of the 660 discontinuity behind the sinking slab, consistent with the presence of hot plume material (average temperature anomalies of 180 to 620 K), while there is not a corresponding downward deflection of the 410 km discontinuity. One interpretation of these disparate observations is suggested based on comparison to existing models of mantle convection and subduction: plume material rising across 660 km discontinuity could be entrained by lateral flow in the transition zone induced by the nearby sinking slab, and thus delaying the rise of hot material across the 410 km discontinuity.
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    Advances in New Zealand's Tephrochronostratigraphy Using Marine Drill Sites: The Neogene (2023)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-06-28
    Description: Three volcanic arcs have been the source of New Zealand's volcanic activity since the Neogene: Northland arc, Coromandel Volcanic Zone (CVZ) and Taupō Volcanic Zone (TVZ). The eruption chronology for the Quaternary, sourced by the TVZ, is well studied and established, whereas the volcanic evolution of the precursor arc systems, like the CVZ (central activity c. 18 to 2 Ma), is poorly known due to limited accessibility to, or identification of, onshore volcanic deposits and their sources. Here, we investigate the marine tephra record of the Neogene, mostly sourced by the CVZ, of cores from IODP Exp. 375 (Sites U1520 and U1526), ODP Leg 181 (Sites 1123, 1124 and 1125), IODP Leg 329 (Site U1371) and DSDP Leg 90 (Site 594) offshore of New Zealand. In total, we identify 306 primary tephra layers in the marine sediments. Multi-approach age models (e.g. biostratigraphy, zircon ages) are used in combination with geochemical fingerprinting (major and trace element compositions) and the stratigraphic context of each marine tephra layer to establish 168 tie-lines between marine tephra layers from different holes and sites. Following this approach, we identify 208 explosive volcanic events in the Neogene between c. 17.5 and 2.6 Ma. This is the first comprehensive study of New Zealand's Neogene explosive volcanism established from tephrochronostratigraphic studies, which reveals continuous volcanic activity between c. 12 and 2.6 Ma with an abrupt compositional change at c. 4.5 Ma, potentially associated with the transition from CVZ to TVZ. Key Points New Zealand's Neogene explosive volcanism based on the marine tephra record Geochemical fingerprinting of marine tephra layers across the study area to establish volcanic events Insights into geochemical variations with time, repose times and spatiotemporal distribution
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    Global census of the significance of giant mesopelagic protists to the marine carbon and silicon cycles (2024)
    Nature Research
    Details
    Publication Date: 2024-06-28
    Description: Thriving in both epipelagic and mesopelagic layers, Rhizaria are biomineralizing protists, mixotrophs or flux-feeders, often reaching gigantic sizes. In situ imaging showed their contribution to oceanic carbon stock, but left their contribution to element cycling unquantified. Here, we compile a global dataset of 167,551 Underwater Vision Profiler 5 Rhizaria images, and apply machine learning models to predict their organic carbon and biogenic silica biomasses in the uppermost 1000 m. We estimate that Rhizaria represent up to 1.7% of mesozooplankton carbon biomass in the top 500 m. Rhizaria biomass, dominated by Phaeodaria, is more than twice as high in the mesopelagic than in the epipelagic layer. Globally, the carbon demand of mesopelagic, flux-feeding Phaeodaria reaches 0.46 Pg C y −1 , representing 3.8 to 9.2% of gravitational carbon export. Furthermore, we show that Rhizaria are a unique source of biogenic silica production in the mesopelagic layer, where no other silicifiers are present. Our global census further highlights the importance of Rhizaria for ocean biogeochemistry.
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    Variations in Volcanism and Tectonics Along the Hotspot‐Influenced Reykjanes Ridge (2023)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-06-28
    Description: Mapping and sampling four sections of the slow-spreading Reykjanes Ridge provide insight into how tectonic and volcanic activity varies with distance from the Iceland plume. The studied areas are characterized by significant variations in water depth, lava chemistry, crustal thickness, thermal structure, and ridge morphology. For each study area, fault pattern and dimension, tectonic strain, seamount morphology, and density are inferred from 15 m-resolution bathymetry. These observations are combined with geochemical analysis from glass samples and sediment thickness estimations along Remotely Operated Vehicle-dive videos. They reveal that (a) tectonic and volcanic activity along the Reykjanes Ridge, do not systematically vary with distance from the plume center. (b) The tectonic geometry appears directly related to the deepening of the brittle/ductile transition and the maximum change in tectonic strain related to the rapid change in crustal thickness and the transition between axial-high and axial valley (∼59.5°N). (c) Across-axis variations in the fault density and sediment thickness provide similar widths for the neo-volcanic zone except in regions of increased seamount emplacement. (d) The variations in seamount density (especially strong for flat-topped seamounts) are not related to the distance from the plume but appear to be correlated with the interaction between the V-shape ridges (VSR) flanking the ridge and the ridge axis. These observations are more compatible with the buoyant upwelling melting instability hypothesis for VSR formation and suggest that buoyant melting instabilities create many small magma batches which by-pass the normal subaxial magmatic plumbing system, erupting over a wider-than-normal area. Key Points The distance from the plume center is not the only factor controlling tectonic and volcanic activity along the Reykjanes Ridge Fault dimensions are primarily controlled by the variation of crustal thermal structure with distance from the hotspot Flat-topped seamount abundances peak where a V-shaped ridge intersects the axis, consistent with a buoyant upwelling melting instability
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    A sustainability and governance index for assessing the EU’s green hydrogen import options (2024)
    In:  Environmental research letters
    Details
    Publication Date: 2024-06-28
    Description: The European Commission's REPowerEU plan set the target of importing 10 million tonnes of 'green' hydrogen into the European Union (EU) by 2030. Against this backdrop, this paper sets out to assess a central question: which countries can be identified as suitable partners for European green hydrogen imports? Using Germany as a reference case, the article develops a quantitative sustainability and governance index (SGI), assessing five dimensions identified as central to ranking external partners: (i) the political will to scale up a green hydrogen sector; (ii) a country's integration with the EU/Germany; (iii) its commitment to international engagement and climate targets and policies; (iv) environmental regulatory effectiveness; and, (v) its governance performance. With this, the SGI offers a novel way of thinking about potential EU green hydrogen partnerships. Rather than focusing on the geography of renewables or cost structures underpinning a country's export potential, the present index captures the extent to which countries may be suitable for green hydrogen partnerships if judged by political and environmental factors. The empirical analysis suggests significant differences between a total of 113 assessed countries as per their overall index ranking, but also the individual dimensions composing the index. This allows drawing conclusions on the policy focus of potential partnerships, taking choices when facing trade-offs regarding individual dimensions, and prioritizing among the latter.
    Language: English
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    Living smaller: acceptance, effects and structural factors in the EU (2024)
    In:  Buildings & cities
    Details
    Publication Date: 2024-06-28
    Description: This article examines limits to per capita living space (i.e. living smaller and/or sharing living space) as a measure for achieving sufficiency in housing. It studies the acceptance, motivation and side-effects of voluntarily reducing living space in five European Union countries: Germany, Hungary, Latvia, Spain and Sweden. Insights are derived from an extensive collection of qualitative empirical material collected from citizen and stakeholder ‘thinking labs’ across the five case countries. Overall, the data reveal an initial reluctance among citizens to reduce living space voluntarily. They also point to some major structural barriers: the housing market and its regulatory framework, social inequality, or dominant societal norms regarding ‘the ideal home’. Enhanced community amenities can compensate for reduced private living space, though contingent upon a clear allocation of rights and responsibilities. Participants also reported positive effects to living smaller, including increased time for leisure activities and proximity to services. This was often coupled with urbanization, which may also be part of living smaller in the future.
    Language: English
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    From grey to green? Tipping a coal region incrementally (2024)
    In:  Global environmental change: human and policy dimensions
    Details
    Publication Date: 2024-06-28
    Description: A rapid and full decarbonisation of both energy and industry is essential to meet the targets in the Paris agreement, which brings coal- and carbon-intensive regions under significant pressure. Some regions have advanced in their transition and can provide insights in the system change processes. In this paper, we investigate the socio-economic transition processes of Essen and Duisburg as part of the wider structural change in the Ruhr Region/ Germany. We explore causes and effects of their trajectories in the last 30 + years and identify differences in outcome as a function of the interventions and/or contextual differences, while investigating whether either city crossed a tipping point in their transition process (yet). Therefore, we specifically evaluate the cities’ development trajectories by seeking evidence for “no”, “incremental” or “radical or tipping” changes in sets of qualitative and quantitative indicators. Our analysis shows that both cities experienced incremental changes in their demographic, economic and political trajectories but we found no evidence for either city to have crossed a tipping point in their transition process yet. However, distinct developments in the cities’ policy narratives and visions indicate qualitative changes while putting them on different development trajectories potentially leading to tipping points in the future. Our study shows that the sequence of interventions and timing are important factors for the trajectory of a region determining the quality of societal change. It also suggests that radical change and tipping are the exception rather than the rule, especially in the highly complex social systems of cities.
    Language: English
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    The role of social capital in managing risks: a bibliometric analysis and literature review (2024)
    In:  Journal of risk research
    Details
    Publication Date: 2024-06-28
    Description: Disasters and crises affect more people around the world than reported in official documents by national or international agencies. Meanwhile, climate change, the COVID-19 pandemic, several wars worldwide and other crises expose a large proportion of the entire population to substantial risks, as well as profoundly affecting human health globally. Many of these impacts remain unnoticed by governance authorities, since many coping strategies are based on bottom-up activities rather than top-down policies. This raises the question: how can we be adequately prepared for a next pandemic or other unforeseen extreme events? Social capital could provide some clues for resilient responses that could be integrated in risk planning and management practice. In this paper, a comprehensive review is provided based on bibliometric analysis. A total number of 2872 published articles were documented and classified. In addition, the geographic locations and the institutional affiliations were assessed and visualized. Four salient research themes were identified as follows: (1) Knowledge sources of the research domain; (2) Individual social capital and risky behaviors; (3) Disaster management and resilience building; and (4) Health issues in the COVID-19 Era. This study offered some practical insights for mobilizing and developing social capital in different phases of risk management. Nevertheless, more inter- and transdisciplinary research across domains is needed to articulate a more comprehensive view of the development of social capital in various risk situations.
    Language: English
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    Status of Concentrated Solar Power Plants Installed Worldwide: Past and Present Data (2024)
    In:  Clean Technologies
    Details
    Publication Date: 2024-06-28
    Description: Solar energy is not only the most abundant energy on earth but it is also renewable. The use of this energy is expanding very rapidly mainly through photovoltaic technology. However, electricity storage remains a bottleneck in tackling solar resource variability. Thus, solar thermal energy becomes of particular interest when energy storage is required, as thermal energy storage is much cheaper than electricity storage. The objective of this paper is to make a short update on the CSP (Concentrated Solar Power) market as of the year 2023. It is based on the CSP-GURU database, which lists information on CSP power plants all over the world. Although this database is open, it is not easy to find UpToDate analysis. An overview of this expanding technology is presented and offers readable figures with the most important information. This includes the evolution of installed capacities worldwide along with upcoming projects (under construction) and technological trends. The evolution of storage capacities and operating temperatures is discussed. Investment costs and levelized cost of electricity are also provided to obtain reliable data for comparison with other energy technologies. Specific land requirements are highlighted, along with overall efficiency. Relevant examples are discussed in this paper. Eventually, it outlines the evolution of the CSP landscape with useful information for scientific and educational purposes.
    Language: English
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    Perceived carbon pricing effectiveness impacts its perceived fairness – Applying and extending a theoretical framework (2024)
    In:  Journal of environmental psychology
    Details
    Publication Date: 2024-06-28
    Description: Based on a theoretical framework inspired by the Greed-Efficiency-Fairness-Hypothesis (GEF), it is argued that perceived effectiveness of climate policies, in addition to other policy beliefs (i.e. perceived personal and distributional consequences), influences perceived overall policy fairness and acceptance. However, links between these policy beliefs and perceived overall fairness as well as whether perceived overall fairness might mediate effects of these beliefs on acceptance remains understudied. This study addresses these gaps and extends the GEF-inspired framework: We add procedural fairness to the list of fairness-relevant beliefs and analyze whether perceived overall carbon pricing fairness integrates and mediates their effect on acceptance, using survey data representative of Germany (n = 4646). Additionally, we test whether adherence to the polluter-pays principle (a general fairness principle) moderates the effects of perceived distributional consequences and effectiveness on perceived overall fairness. Results showed that perceived personal consequences, distributional consequences, procedural fairness, as well as perceived effectiveness, all impact perceived overall fairness, and that the latter (partially) mediates their effects on carbon pricing acceptance. We also find weak evidence that the impact of perceived effectiveness and negative distributional consequences on perceived overall fairness is greater for polluter-pays adherents than for non-adherents. These results suggest that, additionally to perceived personal and distributional consequences as well as fair procedures, perceiving a policy to be effective increases its perceived overall fairness.
    Language: English
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    Shared pooled mobility: expert review from nine disciplines and implications for an emerging transdisciplinary research agenda (2024)
    In:  Environmental research letters
    Details
    Publication Date: 2024-06-28
    Description: Shared pooled mobility has been hailed as a sustainable mobility solution that uses digital innovation to efficiently bundle rides. Multiple disciplines have started investigating and analyzing shared pooled mobility systems. However, there is a lack of cross-community communication making it hard to build upon knowledge from other fields or know which open questions may be of interest to other fields. Here, we identify and review 9 perspectives: transdisciplinary social sciences, social physics, transport simulations, urban and energy economics, psychology, climate change solutions, and the Global South research and provide a common terminology. We identify more than 25 000 papers, with more than 100 fold variation in terms of literature count between research perspectives. Our review demonstrates the intellectual attractivity of this as a novel perceived mode of transportation, but also highlights that real world economics may limit its viability, if not supported with concordant incentives and regulation. We then sketch out cross-disciplinary open questions centered around (1) optimal configuration of ride-pooling systems, (2) empirical studies, and (3) market drivers and implications for the economics of ride-pooling. We call for researchers of different disciplines to actively exchange results and views to advance a transdisciplinary research agenda.
    Language: English
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    Selling CBAM: Die Diplomatie um den CO2-Grenzausgleichsmechanismus der Europäischen Union (2024)
    Potsdam Institute for Climate Impact Research
    In:  Ariadne-Analyse
    Details
    Publication Date: 2024-06-28
    Description: Die Kommunikation zur Einführung des CO2-Grenzausgleichsmechanismus lief zwischen der Europäischen Union und Drittländern rigide und wenig koordiniert ab, so das Ergebnis einer neuen Ariadne-Analyse. Forschende untersuchten, wie die EU ihre Diplomatie dabei organisiert hat, um möglichem handelspolitischem Protest schon während der Entwicklung des CO2-Grenzausgleiches zu begegnen. Die eher reaktive diplomatische Begleitung hat den Ariadne-Forschenden zufolge möglicherweise dazu beigetragen, dem Widerstand von Handelspartnern weniger Angriffsfläche zu bieten und die Akzeptanz des Mechanismus als Ausdruck des Führungsanspruchs der EU bei ambitionierter Klimapolitik zu erhöhen.
    Language: German
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    Selling CBAM: Diplomacy for the European Union’s Carbon Border Adjustment Mechanism (2024)
    Potsdam Institute for Climate Impact Research
    In:  Ariadne-Analyse
    Details
    Publication Date: 2024-06-28
    Description: The European Union’s outreach to third countries during the introduction of the Carbon Border Adjustment Mechanism was rigid and uncoordinated, new Ariadne analysis has found. Researchers investigated how the EU organized its diplomacy to counter trade concerns during the development of the Carbon Border Adjustment Mechanism. According to the Ariadne researchers, the fact that the EU’s diplomatic outreach was rather reactive may have helped to provide less of a target for opposition from trading partners and to increase acceptance of the mechanism as an expression of the EU’s claim to leadership in ambitious climate policy.
    Language: English
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    Für das Meer ist es schon fünf nach zwölf (2024)
    Details
    Publication Date: 2024-06-27
    Description: Neues Konzept soll den Meeresschutz in Kiel voranbringen - Expertin Nicole Walter erläutert die Grundzüge - Mitmach-Angebot am Samstag
    Type: Newspaper report , NonPeerReviewed
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    Wo kommt ihr denn plötzlich her? (2024)
    Details
    Publication Date: 2024-06-27
    Description: Ob Delfine, Seepferdchen oder Schildkröten - in Nord- und Ostsee tummeln sich außergewöhnliche Meeresgäste
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    Die Zukunft der Ozeanforschung (2024)
    Details
    Publication Date: 2024-06-27
    Description: 20 Jahre nach der ersten Planungsidee: Geomar-'- Neubau am Seefischmarkt in Wellingdorf eingeweiht
    Type: Newspaper report , NonPeerReviewed
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    Reassessing the need for carbon dioxide removal: moral implications of alternative climate target pathways (2024)
    Cambridge University Press
    Details
    Publication Date: 2024-06-27
    Description: Non-technical summary Scenarios compatible with the Paris agreement's temperature goal of 1.5 °C involve carbon dioxide removal measures - measures that actively remove CO2 from the atmosphere - on a massive scale. Such large-scale implementations raise significant ethical problems. Van Vuuren et al. (2018), as well as the current IPCC scenarios, show that reduction in energy and or food demand could reduce the need for such activities. There is some reluctance to discuss such societal changes. However, we argue that policy measures enabling societal changes are not necessarily ethically problematic. Therefore, they should be discussed alongside techno-optimistic approaches in any kind of discussions about how to respond to climate change. Technical summary The 1.5 °C goal has given impetus to carbon dioxide removal (CDR) measures, such as bioenergy combined with carbon capture and storage, or afforestation. However, land-based CDR options compete with food production and biodiversity protection. Van Vuuren et al. (2018) looked at alternative pathways including lifestyle changes, low-population projections, or non-CO2 greenhouse gas mitigation, to reach the 1.5 °C temperature objective. Underlined by the recently published IPCC AR6 WGIII report, they show that demand-side management measures are likely to reduce the need for CDR. Yet, policy measures entailed in these scenarios could be associated with ethical problems themselves. In this paper, we therefore investigate ethical implications of four alternative pathways as proposed by Van Vuuren et al. (2018). We find that emission reduction options such as lifestyle changes and reducing population, which are typically perceived as ethically problematic, might be less so on further inspection. In contrast, options associated with less societal transformation and more techno-optimistic approaches turn out to be in need of further scrutiny. The vast majority of emission reduction options considered are not intrinsically ethically problematic; rather everything rests on the precise implementation. Explicitly addressing ethical considerations when developing, advancing, and using integrated assessment scenarios could reignite debates about previously overlooked topics and thereby support necessary societal discourse. Social media summary Policy measures enabling societal changes are not necessarily as ethically problematic as commonly presumed and reduce the need for large-scale CDR
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    Nitrogen loss processes in response to upwelling in a Peruvian coastal setting dominated by denitrification – a mesocosm approach (2021)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-27
    Description: Upwelling of nutrient-rich deep waters make eastern boundary upwelling systems (EBUSs), such as the Humboldt Current system, hot spots of marine productivity. Associated settling of organic matter to depth and consecutive aerobic decomposition results in large subsurface water volumes being oxygen depleted. Under these circumstances, organic matter remineralisation can continue via denitrification, which represents a major loss pathway for bioavailable nitrogen. Additionally, anaerobic ammonium oxidation can remove significant amounts of nitrogen in these areas. Here we assess the interplay of suboxic water upwelling and nitrogen cycling in a manipulative offshore mesocosm experiment. Measured denitrification rates in incubations with water from the oxygen-depleted bottom layer of the mesocosms (via 15N label incubations) mostly ranged between 5.5 and 20 nmol N2 L−1 h−1 (interquartile range), reaching up to 80 nmol N2 L−1 h−1. However, actual in situ rates in the mesocosms, estimated via Michaelis–Menten kinetic scaling, did most likely not exceed 0.2–4.2 nmol N2 L−1 h−1 (interquartile range) due to substrate limitation. In the surrounding Pacific, measured denitrification rates were similar, although indications of substrate limitation were detected only once. In contrast, anammox (anaerobic ammonium oxidation) made only a minor contribution to the overall nitrogen loss when encountered in both the mesocosms and the Pacific Ocean. This was potentially related to organic matter C / N stoichiometry and/or process-specific oxygen and hydrogen sulfide sensitivities. Over the first 38 d of the experiment, total nitrogen loss calculated from in situ rates of denitrification and anammox was comparable to estimates from a full nitrogen budget in the mesocosms and ranged between ∼ 1 and 5.5 µmol N L−1. This represents up to ∼  20 % of the initially bioavailable inorganic and organic nitrogen standing stocks. Interestingly, this loss is comparable to the total amount of particulate organic nitrogen that was exported into the sediment traps at the bottom of the mesocosms at about 20 m depth. Altogether, this suggests that a significant portion, if not the majority of nitrogen that could be exported to depth, is already lost, i.e. converted to N2 in a relatively shallow layer of the surface ocean, provided that there are oxygen-deficient conditions like those during coastal upwelling in our study. Published data for primary productivity and nitrogen loss in all EBUSs reinforce such conclusion.
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    Responses of microbial metabolic rates to non-equilibrated silicate vs calcium-based ocean alkalinity enhancement (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-27
    Description: This study contributes to the inaugural exploration of non-equilibrated Ocean Alkalinity Enhancement (OAE). The manipulation of Total Alkalinity (TA), involving silicate and calcium-based ∆TA gradients ranging from 0 to 600 µmol · L-1, was conducted without prior CO2 sequestration, under natural conditions and at a mesocosm scale (~60 m3). The resulting impact included an increase in pH and a decrease in pCO2, sustained across the experiment, as full natural equilibration via sea-gas exchange did not occur. Implemented in a neritic system under post-bloom conditions, a midway mixing event was simulated. Following an inorganic nutrient addition, discernible delays in bloom formation, as indicated by the Gross Production (GP) and Net Community Production (NCP) rates, as well as by the chlorophyll-a (Chla) concentrations, in relation to the ∆TA gradient, were observed. Notably, the delay was more pronounced for the calcium treatment set compared to the silicate one, where low TA treatments exhibited earlier responses than high TA ones. This delay is likely attributed to the previously documented, species-specific negative relationships between high pH/lowCO2 levels and phytoplankton growth rates. This study underscores the need for further investigation into the implications of this response pattern in terms of trophic transfer and seasonal suitability. Further, it is anticipated that a wider delay in bloom formation would be evident with a larger non equilibrated TA gradient. Thus, highlighting the importance of exploring variations in TA limits for a comprehensive understanding of the OAE’s impacts.
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    Competing effects of wind and buoyancy forcing on recent ocean oxygen trends (2024)
    Details
    Publication Date: 2024-06-27
    Description: Ocean deoxygenation is becoming a major stressor for marine ecosystems. Climate change affects ocean oxygen by altering wind fields and air-sea heat and freshwater fluxes. However, the quantitative contribution of these drivers to ocean deoxygenation remains uncertain. Here, we use a global ocean biogeochemistry model run under historical atmospheric forcing to show that deoxygenation since the late 1960s has been driven mainly by changing air-sea heat and freshwater fluxes and associated changes in solubility and ocean circulation. However, ~60% of this deoxygenation was offset by a wind-driven increase in ventilation and interior oxygen supply, mainly in the Southern Ocean. In the coming decades, the projected slowdown in wind stress intensification, combined with continued ocean warming, could greatly accelerate ocean deoxygenation. While ocean biogeochemistry models under historical atmospheric forcing struggle to reproduce the observed deoxygenation after 2000, fully coupled Earth system models capture the trend, indicating systematic problems in hindcast simulations.
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    Distribution of polysaccharidic and proteinaceous gel−like particles in three cyclonic eddies in the Eastern Tropical North Atlantic (2024)
    Frontiers
    Details
    Publication Date: 2024-06-27
    Description: Transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), two prominent classes of gel−like particles in the ocean primarily produced by phytoplankton, play crucial roles in ecological and biogeochemical processes, influencing microbial nutrition, growth, and particle aggregation. The distribution of these particles is intricately linked to the spatiotemporal dynamics of phytoplankton. Mesoscale cyclonic eddies (CEs) are known to stimulate phytoplankton growth and influence particle transport, but their effects on TEP and CSP remain to be determined. In the Eastern Tropical North Atlantic (ETNA), we examined three CEs: one off the Mauritanian coast during summer (Mau), one offshore during winter (Sal), and another near Brava island during winter. Mau and Brava CEs were in their intensification/maturity phase, while the Sal CE was in its decay phase. Both TEP and CSP concentrations correlated with primary productivity, but TEP increased with chlorophyll−a concentration, whereas elevated CSP coincided also with the highest abundance of pico−nanophytoplankton (〈20 µm), mainly Synechococcus. Both gels exhibited a positive correlation with bacterial biomass production, indicating their consumption by heterotrophic bacteria. TEP total area in the epipelagic waters of all CEs (Mau, Brava, and Sal) was elevated compared to surrounding waters, with on average 4, 2.5, and 1.6−fold higher values, respectively. However, no significant difference in TEP size distribution was observed within any CEs and their surroundings. Similarly, CSP total area increased in the epipelagic waters of Mau and Brava CEs, with on average 5 and 2.4−fold higher values, respectively, compared to surrounding waters. CSP particles were notably larger in these two eddies, while the Sal CE showed no significant difference from surrounding waters in CSP abundance and size. Overall, TEP and CSP exhibited distinct responses to CEs, with increased concentrations during their intensification/maturation stage and remineralization dominating during their decaying stage.
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    Uncovering the role of oxygen on organic carbon cycling: Insights from a continuous culture study with a facultative anaerobic bacterioplankton species (Shewanella baltica) (2024)
    Frontiers
    Details
    Publication Date: 2024-06-26
    Description: Deoxygenation is tied to organic carbon (Corg) supply and utilization in marine systems. Under oxygen-depletion, bacteria maintain respiration using alternative electron acceptors such as nitrate. Since anaerobic respiration's energy yield is lower, Corg remineralization may be reduced and its residence time increased. We investigated the influence of oxygen and alternative electron acceptors' availability on Corg cycling by heterotrophic bacteria during a continuous culture experiment with Shewanella baltica, a facultative anaerobic γ-Proteobacteria in the Baltic Sea. We tested six different oxygen levels, from suboxic (〈5 µmol L-1 ) to fully oxic conditions, using media (salinity=14 g L-1 ) supplied with high (HighN) or low (LowN) inorganic nitrogen concentrations relative to glucose as labile Corg source. Our results show that suboxia limited DOC (glucose) uptake and cell growth only under LowN, while higher availability of alternative electron acceptors seemingly compensated oxygen limitation under HighN. N-loss was observed under suboxia in both nitrogen treatments. Under HighN, N-loss was highest and a C:N loss ratio of ~2.0 indicated that Corg was remineralized via denitrification. Under LowN, the C:N loss ratio under suboxia was higher (~5.5), suggesting dominance of other anaerobic respiration pathways, such as dissimilatory nitrate reduction to ammonium (DNRA). Bacterial growth efficiency was independent of oxygen concentration but higher under LowN (34±3.0%) than HighN (26±1.6%). Oxygen concentration also affected dissolved organic matter (DOM) cycling. Under oxic conditions, the release of dissolved combined carbohydrates was enhanced, and the amino acid-based degradation index (DI) pointed to more diagenetically altered DOM. Our results suggest bacterial Corg uptake in low-oxygen systems dominated by S. baltica can be limited by oxygen but compensated by high nitrate availability. Hence, suboxia diminishes Corg remineralisation only when alternative electron acceptors are lacking. Under high nitrate:Corg supply, denitrification leads to a higher N:C loss ratio, potentially counteracting eutrophication in the long run. Low nitrate:Corg supply may favour other anaerobic respiration pathways like DNRA, which sustains labile nitrogen in the system, potentially intensifying the cycle of eutrophication. Going forward, it will be crucial to establish the validity of our findings for S. baltica in natural systems with diverse organic substrates and microbial consortia.
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    The riddle of eastern tropical Pacific Ocean oxygen levels: the role of the supply by intermediate-depth waters (2021)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-26
    Description: Observed oxygen minimum zones (OMZs) in the tropical Pacific Ocean are located above intermediate-depth waters (IDWs), defined here as the 500–1500 m water layer. Typical climate models do not represent IDW properties well and are characterized by OMZs that are too deep-reaching. We analyze the role of the IDW in the misrepresentation of oxygen levels in a heterogeneous subset of ocean models characterized by a horizontal resolution ranging from 0.1 to 2.8∘. First, we show that forcing the extratropical boundaries (30∘ S and N) to observed oxygen values results in a significant increase in oxygen levels in the intermediate eastern tropical region. Second, we highlight the fact that the Equatorial Intermediate Current System (EICS) is a key feature connecting the western and eastern part of the basin. Typical climate models lack in representing crucial aspects of this supply at intermediate depth, as the EICS is basically absent in models characterized by a resolution lower than 0.25∘. These two aspects add up to a “cascade of biases” that hampers the correct representation of oxygen levels at intermediate depth in the eastern tropical Pacific Ocean and potentially future OMZ projections.
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    The First Network of Ocean Bottom Seismometers in the Red Sea to Investigate the Zabargad Fracture Zone (2024)
    McGill Library
    Details
    Publication Date: 2024-06-26
    Description: In the last decades, the slow-spreading Red Sea rift has been the objective of several geophysical investigations to study the extension of the oceanic crust, the thickness of the sedimentary cover, and the formation of transform faults. However, local seismology datasets are still lacking despite their potential to contribute to the understanding of the tectonic evolution of the Red Sea. The Zabargad Fracture Zone is located in the Northern Red Sea and significantly offsets the rift axis to the East. Thus, it is considered a key tectonic element to understand better the formation of the Red Sea rift. To fill the gap in the dataset availability, we deployed the first passive seismic network in the Red Sea, within the Zabargad Fracture Zone. This network included 12 Lobster OBSs from the DEPAS pool, 2 OBS developed and deployed by Fugro, and 4 portable seismic land stations deployed on islands and onshore on the Saudi Arabian coast. Our data-quality analysis confirms that the head-buoy cable free to strum, as well as other additional elements of the DEPAS OBSs, generate seismic noise at frequencies $〉$ 10 Hz. However, the Fugro OBSs show high-frequency disturbances even if they lack vibrating elements. Comparison between land and OBS stations reveals that noise between 1 and 10 Hz is due to ocean-generated seismic noise, and not due to resonance of the OBS elements. We also found that waveforms of teleseismic earthquakes recorded by the Fugro OBSs, islands, and onshore stations have comparable signal-to-noise ratios. Instead, differences in signal-to-noise ratio for local earthquakes are affected more by site and path effects than instrument settings.
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    Magmatic processes within the plumbing system of the ultraslow-spreading southwest Indian ridge: constraints from olivine, plagioclase and melt inclusions (2024)
    Springer
    Details
    Publication Date: 2024-06-26
    Description: Processes taking place within the magma plumbing system can exert an important control on the composition of mid-ocean ridge basalts (MORB). Plagioclase ultraphyric basalts (PUBs) found at magma-poor mid-ocean ridges exhibit diverse disequilibrium characteristics, which can provide vital insights for distinguishing the complex effects of melt transport from those of source heterogeneity on the compositions of MORBs. Here, we present new insights into magmatic processes using integrated petrologic and geochemical studies of the PUBs from two zones (~ 50° and ~ 64°E longitude) along the ultraslow-spreading southwest Indian ridge (SWIR). The studied PUBs have complex mineral morphologies, including skeletal and acicular crystals, glomerocrysts with open and closed structure, reverse and normally zoned crystals and external and internal resorption even in single samples. Both low- and high-Fo olivine and An plagioclase crystals are in disequilibrium with their matrix glasses. Some plagioclase phenocrysts have repeated oscillatory zoning (An77–86) going from their core to rim and an abrupt decrease in An content toward the rim. Disequilibrium Sr isotopic compositions are present at several scales: between cores and rims of plagioclase crystals, between different plagioclase crystals and between plagioclase and their host lavas. Inferred pressures of magma storage range from 0.3 to 11.3 kbar. The textural and compositional diversity of crystals together with the variability in melt compositions reflect the combined influences of source heterogeneity and magmatic processes (e.g. crystallization, assimilation and magma mixing processes) taking place within crystal mushes. Our data combined with previous studies suggest that the magmatic processes within the SWIR magma plumbing system involve formation, disaggregation and juxtaposition of crystal-rich mush zones.
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    Ostsee aus der Schnorchelsicht (2024)
    Details
    Publication Date: 2024-06-25
    Description: Meeresschutz in nächster Nähe: Ein Pilotprojekt soll Schulklassen für ihre Umwelt sensibilisieren
    Type: Newspaper report , NonPeerReviewed
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    Zeitbomben am Meeresgrund (2024)
    Details
    Publication Date: 2024-06-25
    Description: Forscher von Geomar untersuchen Weltkriegsmunition in der Ostsee - Sie ist vielfältiger als gedacht
    Type: Newspaper report , NonPeerReviewed
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    Visual 3D Reconstruction in the Deep Sea : from Geometric and Radiometric Perspectives (2024)
    Details
    Publication Date: 2024-06-25
    Description: Underwater vision systems have become popular in ocean research. However, imaging in the deep sea poses significant challenges. Firstly, cameras enclosed in waterproof housings must withstand extreme water pressure, while light undergoes refraction as it traverses multiple media layers. Secondly, light absorption and scattering in water degrade image quality. Additionally, artificial illumination in the deep sea creates unique visual effects. All these factors collectively contribute to the complexity and difficulty of visual 3D reconstruction in the deep sea. This dissertation provides comprehensive solutions to the challenges encountered in deep sea visual 3D reconstruction, encompassing both hardware and software components. To address geometric refraction effects, it thoroughly analyzes dome refractive geometry and proposes mechanical adjustments for centering cameras inside domes to mitigate refraction effects. Additionally, recognizing the wide use of flat port interfaces, the dissertation explores effective methods to correct flat refraction effects for underwater photogrammetry. Furthermore, the dissertation delves into radiometric issues arising from light absorption and scattering in water, especially concerning artificial illumination in deep-sea imaging. It explores physical models of underwater image formation and develops a general model suitable for restoring various types of underwater image, especially in environments with complex artificial illumination. This model enables the simultaneous removal of artificial lighting patterns and the restoration of true colors. Moreover, the dissertation demonstrates several successful applications of the techniques developed within its scope. It showcases their efficacy in various camera system designs, underwater 3D reconstruction, and improving complex illumination configurations within imaging systems.
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    3. Wochenbericht MSM129/2 (2024)
    GEOMAR
    Details
    Publication Date: 2024-06-25
    Description: FS Maria S Merian – MSM129/2 07.06.2024 – 06.07.2024 St. John’s (Kanada) – Reykjavik (Island) 3. Wochenbericht (17.06. – 23.06.2024)
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    Long-term culture system for deep-sea mussels Gigantidas childressi (2024)
    ASLO (Association for the Sciences of Limnology and Oceanography) | Wiley
    Details
    Publication Date: 2024-06-24
    Description: The simulation of deep-sea conditions in laboratories is technically challenging but necessary for experiments that aim at a deeper understanding of physiological mechanisms or host-symbiont interactions of deep-sea organisms. In a proof-of-concept study, we designed a recirculating system for long-term culture (〉2 yr) of deep-sea mussels Gigantidas childressi (previously Bathymodiolus childressi). Mussels were automatically (and safely) supplied with a maximum stable level of ~60 μmol L−1 methane in seawater using a novel methane–air mixing system. Experimental animals also received daily doses of live microalgae. Condition indices of cultured G. childressi remained high over the years, and low shell growth rates could be detected, too, which is indicative of positive energy budgets. Using stable isotope data, we demonstrate that G. childressi in our culture system gained energy, both, from the digestion of methane-oxidizing endosymbionts and from digesting particulate food (microalgae). Limitations of the system, as well as opportunities for future experimental approaches involving deep-sea mussels, are discussed.
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    Introduction to special issue on seabed prospecting technology (2024)
    Wiley
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    Publication Date: 2024-06-24
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    Zooplankton seasonal vertical migration in an optimality-based plankton ecosystem model (2024)
    Oxford University Press
    Details
    Publication Date: 2024-06-24
    Description: Several species from various zooplankton taxa perform seasonal vertical migrations (SVM) of typically several hundred meters between the surface layer and overwintering depths, particularly in high-latitude regions. We use OPtimality-based PLAnkton (OPPLA) ecosystem model) to simulate SVM behavior in zooplankton in the Labrador Sea. Zooplankton in OPPLA is a generic functional group without life cycle, which facilitates analyzing SVM evolutionary stability and interactions between SVM and the plankton ecosystem. A sensitivity analysis of SVM-related parameters reveals that SVM can amplify the seasonal variations of phytoplankton and zooplankton and enhance the reduction of summer surface nutrient concentrations. SVM is often explained as a strategy to reduce exposure to visual predators during winter. We find that species doing SVM can persist and even dominate the summer-time zooplankton community, even in the presence of Stayers, which have the same traits as the migrators, but do not perform SVM. The advantage of SVM depends strongly on the timing of the seasonal migrations, particularly the day of ascent. The presence of higher (visual) predators tends to suppress the Stayers in our simulations, whereas the SVM strategy can persist in the presence of non-migrating species even without higher predators.
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    Regional Variation in Extratropical North Atlantic Air‐Sea Interaction 1960–2020 (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-06-24
    Description: Air-sea interaction in late boreal winter is studied over the extratropical North Atlantic (NA) during 1960–2020 by examining the relationship between sea-surface temperature (SST) and total turbulent heat flux (THF). The two quantities are positively correlated on interannual timescales over the central-midlatitude and subpolar NA, suggesting the atmosphere on average drives SST and THF variability is independent of SST. On decadal timescales and over the central-midlatitude NA the correlation is negative, suggesting ocean processes on average drive SST and THF variability is sensitive to SST. The correlation is positive over the subpolar NA. There, interannual and decadal THF variability is governed by the North Atlantic Oscillation (NAO). During the major late 20th and early 21st century SST increase in the subpolar NA diminishing oceanic heat loss associated with a weakening NAO was observed. This study suggests that the atmosphere is more sensitive to SST over the central-midlatitude than subpolar NA. Key Points: - Regional variation in the nature of air-sea interaction over the extratropical North Atlantic (NA) north of 35°N - Timescale dependence in relationship between sea-surface temperature (SST) and turbulent heat flux over the central-midlatitude NA - The atmosphere is more sensitive to SST variability over the central-midlatitude than subpolar NA
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    Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-24
    Description: The addition of carbonate minerals to seawater through an artificial ocean alkalinity enhancement (OAE) process increases the concentrations of hydroxide, bicarbonate, and carbonate ions. This leads to changes in the pH and the buffering capacity of the seawater. Consequently, OAE could have relevant effects on marine organisms and in the speciation and concentration of trace metals that are essential for their physiology. During September and October 2021, a mesocosm experiment was carried out in the coastal waters of Gran Canaria (Spain), consisting on the controlled variation of total alkalinity (TA). Different concentrations of carbonate salts (NaHCO3 and Na2CO3) previously homogenized were added to each mesocosm to achieve an alkalinity gradient between Δ0 to Δ2400 µmol L−1. The lowest point of the gradient was 2400 µmol kg−1, being the natural alkalinity of the medium, and the highest point was 4800 µmol kg−1. Iron (Fe) speciation was monitored during this experiment to analyse total dissolved iron (TdFe, unfiltered samples), dissolved iron (dFe, filtered through a 0.2 µm pore size filter), soluble iron (sFe, filtered through a 0.02 µm pore size filter), dissolved labile iron (dFe′), iron-binding ligands (LFe), and their conditional stability constants () because of change due to OAE and the experimental conditions in each mesocosm. Observed iron concentrations were within the expected range for coastal waters, with no significant increases due to OAE. However, there were variations in Fe size fractionation during the experiment. This could potentially be due to chemical changes caused by OAE, but such an effect is masked by the stronger biological interactions. In terms of size fractionation, sFe was below 1.0 nmol L−1, dFe concentrations were within 0.5–4.0 nmol L−1, and TdFe was within 1.5–7.5 nmol L−1. Our results show that over 99 % of Fe was complexed, mainly by L1 and L2 ligands with ranging between 10.92 ± 0.11 and 12.68 ± 0.32, with LFe ranging from 1.51 ± 0.18 to 12.3 ± 1.8 nmol L−1. Our data on iron size fractionation, concentration, and iron-binding ligands substantiate that the introduction of sodium salts in this mesocosm experiment did not modify iron dynamics. As a consequence, phytoplankton remained unaffected by alterations in this crucial element.
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    1. Wochenbericht M201 VebVolc (2024)
    GEOMAR Helmholtz Centre for Ocean Research
    Details
    Publication Date: 2024-06-24
    Description: FS METEOR Expedition M201 VebVolc, 09.06. – 18.07.2024 | Reykjavik – Praia da Vitoria
    Type: Report , NonPeerReviewed
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    Hazardous explosive eruptions of a recharging multi-cyclic island arc caldera (2024)
    Nature Research
    Details
    Publication Date: 2024-06-24
    Description: Caldera-forming eruptions of silicic volcanic systems are among the most devastating events on Earth. By contrast, post-collapse volcanic activity initiating new caldera cycles is generally considered less hazardous. Formed after Santorini’s latest caldera-forming eruption of ~1600 bce , the Kameni Volcano in the southern Aegean Sea enables the eruptive evolution of a recharging multi-cyclic caldera to be reconstructed. Kameni’s eruptive record has been documented by onshore products and historical descriptions of mainly effusive eruptions dating back to 197 bce . Here we combine high-resolution seismic reflection data with cored lithologies from International Ocean Discovery Program Expedition 398 at four sites to determine the submarine architecture and volcanic history of intra-caldera deposits from Kameni. Our shore-crossing analysis reveals the deposits of a submarine explosive eruption that produced up to 3.1 km 3 of pumice and ash, which we relate to a historical eruption in 726 ce . The estimated volcanic explosivity index of magnitude 5 exceeds previously considered worst-case eruptive scenarios for Santorini. Our finding that the Santorini caldera is capable of producing large explosive eruptions at an early stage in the caldera cycle implies an elevated hazard potential for the eastern Mediterranean region, and potentially for other recharging silicic calderas.
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  • 78
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    Early arrival of spring‐spawning Atlantic herring Clupea harengus at their spawning ground in the Kiel Fjord, western Baltic, relates to increasing winter seawater temperature (2024)
    Wiley
    Details
    Publication Date: 2024-06-24
    Description: The disturbance of marine organism phenology due to climate change and the subsequent effects on recruitment success are still poorly understood, especially in migratory fish species, such as the Atlantic herring (Clupea harengus; Clupeidae). Here we used the commercial catch data from a local fisher over a 50-year period (1971–2020) to estimate western Baltic spring-spawning (WBSS) herring mean arrival time Q50 (i.e., the week when 50% of the total fish catches had been made) at their spawning ground within the Kiel Fjord, southwest Baltic Sea, and the duration of the spawning season for each year. The relationship between the seawater temperature in the Kiel Bight and other environmental parameters (such as water salinity, North Atlantic and Atlantic multidecadal oscillations) and Q50 was evaluated using a general linear model to test the hypothesis that fish arrived earlier after warm than cold winters. We also estimated the accumulated thermal time to Q50 during gonadal development to estimate the effects of seawater temperature on the variations of Q50. The results of this study revealed a dramatic decrease in herring catches within the Kiel Fjord since the mid-1990s, as documented for the whole southwestern Baltic Sea. Warmer winter seawater temperature was the only factor related to an earlier arrival (1 week for one January seawater temperature degree increase) of herring at their spawning ground. The relationship was found for the first time on week 52 of the year prior to spawning and was the strongest (50% of the variability explained) from the fourth week of January (8 weeks before the mean Q50 among the studied years). A thermal constant to Q50 (~316°C day) was found when temperatures were integrated from the 49th week of the year prior to spawning. These results indicate that seawater temperature enhanced the speed of gonadal maturation during the latest phases of gametogenesis, leading to an early fish arrival under warm conditions. The duration of the spawning season was elongated during warmer years, therefore potentially mitigating the effects of trophic mismatch when fish spawn early. The results of this study highlight the altering effects of climate change on the spawning activity of a migratory fish species in the Baltic Sea where fast global changes presage that in other coastal areas worldwide
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  • 79
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    Recycled materials and secondary processes controlled the chemical and isotopic compositions of bubbling gases discharged from two adjacent geothermal springs in the Northern Luzon Arc (2024)
    Elsevier
    Details
    Publication Date: 2024-06-24
    Description: Highlights • Statistically different gas geochemistry was observed in two adjacent springs. • About 74% of helium was contributed by the mantle. • Excess N2 relative to Ar was attributed to subducted materials and seawater mixing. • Magmatic CO2 has been largely removed by calcite precipitation in the reaction zone. • The residual CO2 may also be supplied by microbial oxidation of alkanes. Gas emissions from hydrothermal systems can serve as indicators of subsurface activity. In addition to gas sources, hydrothermal gas geochemistry is strongly influenced by secondary processes that occur during/after hydrothermal circulation. Here, we observed statistically significant differences in the geochemical characteristics (except for helium isotopes) of bubbling gases discharged from two adjacent vents in the Northern Luzon Arc. Helium (3He/4He = 4.25–7.09 Ra) in both vents was controlled by mixing between mantle and crustal components, where about 74% of helium was contributed by the mantle. Differences in N2/Ar ratios (∼ 300–330) of the two neighboring springs are attributed to subducted materials and seawater mixing (contributing ∼2.5% N2 and Ar), rather than phase separation in the reaction zone. Specifically, Ar was mainly supplied by atmospheric components that dissolved in the percolated seawater with only 8%–9% contributed by the excess radiogenic 40Ar. Excess N2 relative to Ar was mainly supplied by the decomposition of subducted materials (83%–92%) of the South China Sea plate beneath the Philippine Sea Plate. The Lutao gases showed low CO2 concentrations (0.07–22.2 mmol/mol), despite the high 3He/4He ratios indicating a significant contribution of magmatic components. Magmatic CO2 may have been largely consumed by the high Ca Lutao vent fluids via carbonate precipitation in the reaction zone. Alternatively, stable carbon isotope compositions (δ13C) indicate that Lutao CO2 may be supplied by microbial oxidation of alkanes (e.g., CH4 with concentrations of 14.6–173 mmol/mol in the samples), with fractionation factor ΔCO2–CH4 ranging from −15‰ to −25‰ and conversion rates of 〈10%. Up to 65% of the CO2 in the 2016 samples experienced secondary calcite precipitation in the discharge zone. Our results indicate that recycled subducted materials could potentially affect the geochemical characteristics of gases discharged from arc-volcanic systems. In addition, the influence of secondary processes needs to be considered before tracing the sources of hydrothermal fluids and/or gases, especially in shallow-water hydrothermal systems.
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  • 80
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    3. Wochenbericht M201 VebVolc (2024)
    GEOMAR Helmholtz Centre for Ocean Research
    Details
    Publication Date: 2024-06-24
    Description: FS METEOR Expedition M201 VebVolc, 09.06. – 18.07.2024 | Reykjavik – Praia da Vitoria
    Type: Report , NonPeerReviewed
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  • 81
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    A comparison of the atmospheric response to the Weddell Sea Polynya in atmospheric general circulation models (AGCMs) of varying resolutions (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-24
    Description: The Weddell Sea Polynya (WSP) is a large opening within the sea ice cover of the Weddell Sea sector. It has been a rare event in the satellite period, appearing between 1973 and 1976 and again in 2016/2017. Coupled modelling studies have suggested that there may be a large-scale atmospheric response to the WSP. Here, the direct atmospheric response to the WSP is estimated from atmosphere-only numerical experiments. Three different models, the HadGEM3 UK Met Office model, the ECHAM5 Max Planck Institute model, and the OpenIFS ECMWF model, each at two different resolutions, are used to test the robustness of our results. The use of large ensembles reduces the weather variability and isolates the atmospheric response. Results show a large (∼100-200 Wm-2) turbulent air-sea flux anomaly above the polynya. The response to the WSP is local and of short duration (barely outlasting the WSP) with a similar magnitude and spatial pattern of lower-tropospheric warming and increase in precipitation in all six configurations. All models show a weak decrease in surface pressure over the WSP, but this response is small (∼2 hPa) in comparison to internal variability. The dynamic response is inconsistent between models and resolutions above the boundary layer, suggesting a weak or null response that is covered by internal variability aloft. The higher resolution does not alter the pattern of the response but increases its magnitude by up ∼50% in two of the three models. The response is influenced by natural variability in the westerly jet. The models perform well against ERA5 reanalysis data for the 1974 WSP in spatial response and magnitude, showing a turbulent heat flux of approximately 150 W m-2.
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  • 82
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    Tropospheric sulfate from Cumbre Vieja (La Palma) observed over Cabo Verde contrasted with background conditions: a lidar case study of aerosol extinction, backscatter, depolarization and lidar ratio profiles at 355, 532 and 1064 nm (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-24
    Description: In September 2021, volcanic aerosol (mainly freshly formed sulfate plumes) originating from the eruption of Cumbre Vieja on La Palma, Canary Islands, Spain, crossed Cabo Verde at altitudes below 2 km. On 24 September 2021, an extraordinary large aerosol optical depth (AOD) close to 1 (daily mean at 500 nm) was observed at Mindelo, Cabo Verde. This event provided favorable conditions to obtain lidar-derived profiles of extinction and backscatter coefficients, lidar ratio, and depolarization ratio at 355, 532 and 1064 nm in the sulfate aerosol plume. A novel feature of the lidar system operated at Mindelo is the availability of extinction, lidar ratio and depolarization measurements at 1064 nm in addition to the standard wavelengths of 355 and 532 nm. Having measurements of these parameters at all three wavelengths is a major advantage for the aerosol characterization and in aerosol typing efforts as the lidar ratio and the particle linear depolarization ratio are key parameters for this purpose. In this article, we present the key results of the lidar observations obtained on one specific day, namely on 24 September 2021 at 04:38-05:57 UTC, including the first ever measurements of the particle extinction coefficient, the lidar ratio and the depolarization ratio at 1064 nm for volcanic sulfate, and discuss the findings in terms of aerosol optical properties and mass concentrations by comparison with a reference observation (16 September 2021) representing the typical background conditions before the start of the eruptions. We found an unusual high particle extinction coefficient of 721 +/- 51, 549 +/- 38 and 178 +/- 13 Mm - 1 , as well as an enhanced lidar ratio of 66.9 +/- 10.1, 60.2 +/- 9.2 and 30.8 +/- 8.7 sr at 355, 532 and 1064 nm, respectively, in the sulfate-dominated planetary boundary layer (PBL). The particle linear depolarization ratio was 〈= 0.9 % at all respective wavelengths. It is the first time that lidar-derived intensive aerosol optical properties could be derived for volcanic sulfate at all three wavelengths, and thus it is a highly valuable data set for global aerosol characterization. The lidar analysis also revealed a sulfate-related AOD of about 0.35 +/- 0.03 at 532 nm of the total PBL-related AOD of 0.43. The rest of the AOD contribution was caused by a lofted Saharan dust layer extending from 1.4 to 5 km and leading to a total AOD of 0.79 at 532 nm. Volcanic ash contribution to the observed aerosol plumes could be mostly excluded based on trajectory analysis and the observed optical properties. Peak mass concentration was 178.5 +/- 44.6 mu g m - 3 in the volcanic-influenced and sulfate-dominated polluted PBL, showing the hazardous potential of such sulfate plumes to significantly worsen local air quality even at remote locations.
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  • 83
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    Investigating the effect of silicate- and calcium-based ocean alkalinity enhancement on diatom silicification (2024)
    Coper
    Details
    Publication Date: 2024-06-24
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  • 84
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    Late-Pleistocene rejuvenated volcanism and flank collapse deposits on a Cretaceous seamount near El Hierro, Canary Archipelago (2024)
    Elsevier
    Details
    Publication Date: 2024-06-24
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 85
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    Marine habitat mapping (2024)
    European Marine Board
    Details
    Publication Date: 2024-06-24
    Description: EMB Future Science Brief No. 11 ‘Marine habitat mapping’ presents science and policy needs and recommendations to advance next-generation marine habitat mapping. It highlights current methods and future trends in the acquisition of data from the seabed and water column via remote sensing and direct, in situ techniques. It discusses combining data to produce maps using modelling approaches and presents recommendations for adopting fit-for-purpose habitat classification schemes. It also provides an overview of what has been mapped and where within the European sea-basins, highlights the need to increase the quality and resolution of marine habitat maps. It identifies critical gaps in habitat types and geographic extent, including the coastal areas, the deep sea, Natura 2000 sites and other Marine Protected Areas across all regional seas. Finally, it describes the need to improve the assessment and communication of uncertainty and confidence in maps, and to make maps more easily accessible to a variety of stakeholders to increase their value for end-users and to the public for Ocean literacy.
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  • 86
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    Convolution of individual and group identity: self-reliance increases polarisation in basic opinion model (2024)
    In:  Humanities and Social Sciences Communications
    Details
    Publication Date: 2024-06-21
    Description: Opinion formation within society follows complex dynamics. Towards its understanding, axiomatic theory can complement data analysis. To this end we propose an axiomatic model of opinion formation that aims to capture the interaction of individual conviction with social influence in a minimalist fashion. Despite only representing that (1) agents have an initial conviction with respect to a topic and are (2) influenced by their neighbours, the model shows emergence of opinion clusters from an initially unstructured state. Here, we show that increasing individual self-reliance makes agents more likely to align their socially influenced opinion with their inner conviction which concomitantly leads to increased polarisation. The opinion drift observed with increasing self-reliance may be a plausible analogue of polarisation trends in the real world. Modelling the basic traits of striving for individual versus group identity, we find a trade-off between individual fulfilment and societal cohesion. This finding from fundamental assumptions can serve as a building block to explain opinion polarisation.
    Language: English
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  • 87
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    Kohlenstoffarmer Wasserstoff in der Europäischen Union: Ein kohärenter regulatorischer Rahmen. - Deutschsprachige Zusammenfassung. Originalstudie in englischer Version erhältlich (2024)
    Potsdam Institute for Climate Impact Research
    In:  Ariadne-Analyse
    Details
    Publication Date: 2024-06-21
    Description: Wasserstoff wird eine entscheidende Rolle bei der Dekarbonisierung von schwer elektrifizierbaren Sektoren spielen, doch die Produktion von erneuerbarem Wasserstoff steckt noch in der Anfangsphase. Aus diesem Grund wird die Nutzung von kohlenstoffarmem Wasserstoff aus nicht-erneuerbaren Quellen als Übergangslösung auf dem Weg zu einer erneuerbaren Wasserstoffwirtschaft diskutiert. Kohlenstoffarmer Wasserstoff umfasst unterschiedliche Produktionsmethoden, wie die Herstellung aus fossilen Brennstoffen mit nachfolgender Kohlenstoffabscheidung und -speicherung (CCS) oder -nutzung (CCU), sowie die Elektrolyse mit Strom aus Kernenergie. Um eine positive Klimaschutzwirkung durch den Einsatz von kohlenstoffarmem Wasserstoff sicherzustellen, müssen signifikante Reduzierungen von Treibhausgasemissionen (THG) erzielt werden. Dies sollte durch einen kohärenten regulatorischen Rahmen für die Produktion und den Import von kohlenstoffarmem Wasserstoff auf EU-Ebene gewährleistet werden. Diese Analyse gibt demnach Einblicke in den aktuellen Stand der EU-Gesetzgebung zur Produktion und zum Import von kohlenstoffarmem Wasserstoff und untersucht, ob die verbundenen Risiken und Herausforderungen für einen wirksamen Klimaschutz durch den Rechtsrahmen abgedeckt sind. Da jede Produktionsmethode durch unterschiedliche Herausforderungen charakterisiert ist, untersucht die Analyse die jeweiligen Regelungen gasbasierter Wasserstoffproduktion mit CCS, gasbasierter Wasserstoffproduktion mit CCU, sowie die Wasserstoffproduktion mit Kernenergie im Einzelnen. Auf dieser Grundlage werden Empfehlungen für die Entwicklung des regulatorischen Rahmens für innereuropäisch produzierten und importierten kohlenstoffarmem Wasserstoff formuliert.
    Language: German
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  • 88
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    Low carbon hydrogen in the European Union: A coherent regulatory framework (2024)
    Potsdam Institute for Climate Impact Research
    In:  Ariadne-Analyse
    Details
    Publication Date: 2024-06-21
    Description: Renewable hydrogen is necessary for the decarbonization of sectors that are difficult to electrify, such as industry and aviation, and as a storage medium for surplus electricity from renewable sources.
    Language: English
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  • 89
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    Systementwicklung – Wasserstoff, Infrastrukturplanung und der geltende Rechtsrahmen (2024)
    Potsdam Institute for Climate Impact Research
    In:  Ariadne-Analyse
    Details
    Publication Date: 2024-06-21
    Description: Wasserstoff ist durch seine vielfältigen Nutzungsmöglichkeiten ein Schlüsselelement der Sektorenkopplung auf dem Weg zur Klimaneutralität. Damit Wasserstoff aber für unterschiedliche, momentan noch nicht abschließend definierte Anwendungsbereiche genutzt werden kann, sind entsprechende technologische Infrastrukturen notwendig. Diese umfassen die Produktion, die Speicherung und den Transport von Wasserstoff. Während bei der Bereitstellung von Wasserstoff konkrete Ziele formuliert wurden und auch hinsichtlich der Anwendungsbereiche deutliche, wenn auch konkurrierende Vorstellungen bestehen, sind bei der Wasserstoffinfrastruktur viele grundsätzliche Fragen offen. Vor diesem Hintergrund diskutiert diese Analyse, unbeschadet der Tatsache, dass bislang weder eine Systementwicklungsplanung noch ein abgeschlossenes Wasserstoffwirtschaftsrecht in Deutschland bestehen, wie viel „System“ und „Planung“ bereits jetzt durch Stakeholder und den einschlägigen Rechtsrahmen mit Blick auf Wasserstoff mitgedacht werden. Dabei orientiert sich die Analyse an folgenden Fragen: Erfolgt die Regulierung in Sachen Wasserstoff bereits jetzt aus der Sicht eines geschlossenen Energiesystems? Sehen die Stakeholder Wasserstoff bereits systemisch und interpretieren sie den bestehenden Rechtsrahmen zur Planung der Infrastrukturen entsprechend? Folgen die Vorstellungen der Wasserstoffinfrastruktur schon jetzt systemischen Ansätzen oder stellen sie vielmehr eine weitere sektorale Infrastruktur und Planung dar? Die vorliegende Analyse zeigt, dass Stakeholder nicht grundsätzlich einen systemischen Blick auf Wasserstoff haben und gerade bei wirtschaftlichen Akteuren teilweise eine sektorale Betrachtung überwiegt. Hier sollte beobachtet werden, in welcher Weise bei der Realisierung des seit dem Sommer 2023 vorliegenden Vorschlag des Wasserstoffkernnetzes (FNB Gas 2023), Nutzerbedarfe in die Planungsprozesse einbezogen werden. Noch weniger berücksichtigen einschlägige Rechtsvorschriften die systemische Bedeutung von Wasserstoff. Beachtenswert ist dabei unter anderem, dass die bestehenden nationalen Vorschriften zur Einführung einer Wasserstoffnetzplanung wenig bis gar keine Bezugnahme zur systemischen Funktionsweise von Wasserstoff aufweisen. Im europäischen Recht entfaltet die Erneuerbare-Energien-Richtlinie durch das Kriterium der Zusätzlichkeit bei neu in Betrieb genommenen Anlagen hingegen durchaus eine vorgelagerte systemische Entscheidungswirkung. In der deutschen Planungspraxis könnte der systemische Aspekt dadurch gestärkt werden, dass Strom- und Wasserstoffnetzplanungen über Einzelaspekte wie Power-to-Gas-Anlagen in Zukunft von vornherein integriert angelegt werden.
    Language: German
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  • 90
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    Calcium Isotope Ratios in Serum: A Novel Biomarker of Bone and Vessel Calcium Balance in Patients on Dialysis: TH-OR38 (2023)
    American Society of Nephrology
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    Publication Date: 2024-06-21
    Type: Article , NonPeerReviewed
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  • 91
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    Controls on mesophotic carbonate facies and sediment distribution across the Maltese shelf, central Mediterranean Sea (2024)
    Details
    Publication Date: 2024-06-21
    Description: Although ~20% of global carbonate occurs on extra-tropical shelves, our understanding of these depositional environments still lags far behind that of tropical carbonate platforms. The Maltese shelf in the central Mediterranean offers an opportunity to study in situ facies distribution in a light-dominated extra-tropical carbonate platform and the factors controlling them. The Maltese shelf visually exhibits three main facies: seagrass meadows; sand flats/bedforms and maerl. While visually distinctive, the allochem composition of the sediment does not offer a clear differentiation of all three but rather a gradient. This gradient is marked by increasing grain size with depth, a transition from green to red calcareous algae and an increase in the fraction of low Mg calcite. While some of these features could be explained by changes in light availability, other factors are also in play. Internal waves, currents and baffling by seafloor vegetation appear to play important roles in governing the sedimentary texture and composition across the Maltese shelf. The role of vegetated substrate is of greater importance in Mediterranean C-type carbonate factories and could be an important marker to identify them in the geological record.
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  • 92
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    Exploring the Deep Sea: Combining a Bistable Mechanism with Origami-Inspired Soft Actuators (2024)
    IEEE
    Details
    Publication Date: 2024-06-21
    Description: Sediment sampling is a prevalent approach for ex- ploring and understanding the ocean and its change over time. Unfortunately, the sampling process can be very costly due to the logistics that involve the transportation and deployment of the Remotely Operative Vehicle (ROV), specifically designed for this task. In a collaboration of marine scientists and engineers, this work focuses on developing a lightweight, modular and cost efficient actuation system for deep-sea suction-sampling. We propose a binary actuation system to manipulate the sampling tube directly instead of the tube being guided by a traditional manipulator. The core of the actuation system are bistable actuators that combine origami-inspired soft actuators with a bistable mechanism to form a lightweight but still robust system. This concept aims to lower the cost of deep-sea sediment sampling by offering the option to replace the currently used hydraulic titanium manipulator, that is traditionally used for deep-sea research. We present the design, manufacturing and proof of concept for the combination of a origami-inspired soft actuator with a bistable mechanism.
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  • 93
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    From Symmetric Rifting to Asymmetric Spreading - Insights into Back-Arc Formation in the Central Mariana Trough (2024)
    Details
    Publication Date: 2024-06-21
    Description: The Mariana Trough is the youngest back-arc basin in a series of basins and arcs that developed behind the Mariana subduction zone in the western Pacific. Active seafloor spreading is ongoing at a spreading axis close the Mariana Arc resulting in a pronounced asymmetric configuration (double rate to the west 2:1) at 17° N. The formation of back-arc basins is controlled by the subducting slab, which regulates the temporal development of mantle flow, entrainment of fluids and hydrous melts together with the magma generation. To better understand the formation process of back-arc basins and the asymmetry of the central Mariana Trough, we combined 2-D P-wave traveltime tomography results together with high-resolution bathymetric data. Here, we show that the crust in the central Mariana Trough is 6.5-9.5 km thick, which is unusual for oceanic crust. The lower crust exhibits average seismic velocities of 6.5-7.2 km/s. High-velocity anomalies (7.4-7.9 km/s) in the lower crust at the margins of the Mariana Trough indicate that magmatic accretion process was affected by hydrous melting during rifting. While the Mariana Trough developed from a rather symmetric rifting (0.89:1) to a strongly asymmetric seafloor spreading stage (5.33:1), the contribution of hydrous melts declined and the opening direction changed. The asymmetric plate motions and the temporal change of the slab component influenced strongly the formation of the back-arc basin.
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  • 94
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    Calcium Isotopes: A Novel Biomarker of Bone Mineralization in CKD: TH-OR16 (2020)
    American Society of Nephrology
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    Publication Date: 2024-06-21
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  • 95
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    The Gas Hydrate System of the Western Black Sea Basin (2024)
    Details
    Publication Date: 2024-06-21
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  • 96
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    Unravelling instrumental mass fractionation of MC-ICP-MS using neodymium isotopes (2024)
    Elsevier
    Details
    Publication Date: 2024-06-20
    Description: Since the initial discovery of the non-exponential mass fractionation (non-EMF) of Nd isotopes analysis in 2002, similar deviations from an EMF pattern have been reported for measurements of a number of isotope systems (e.g., Si, Ge, Sr, Sn, Ba, Yb, W, Os, Hg and Pb) with MC-ICP-MS. However, the previous controversial reports on the magnitude of the deviations from EMF suggest that instrumental mass bias behaviour of MC-ICP-MS is neither fully understood nor well-characterised. Consequently, the standard approach of using a mass dependent fractionation (MDF) correction model (e.g., exponential law) may lead to both inaccurate and imprecise results. In this study, we systematically characterise the instrumental mass fractionation of MC-ICP-MS using Nd isotope measurements carried out under different plasma conditions, quantified using the normalised argon index (NAI) as an estimate of plasma temperature. Our results indicate that the mass bias of MC-ICP-MS is not always a simple exponential function of mass but shows systematic deviations from an EMF behaviour, which are closely associated with decreased NAIs. As a result, the conventional exponential correction yields a 143Nd/144Nd value of 0.512257 for the reference material BHVO-2 when the NAI is low, which is 722 ppm lower than the reported value of 0.512979. By tuning the plasma to higher NAIs (higher plasma temperatures), the deviations from the EMF array are systematically attenuated and the exponential correction is able to correct for the instrumental mass bias under high NAIs. In contrast, a regression correction model for Nd isotopes is developed to account for the observed mass fractionation behaviour that does not follow EMF under low NAIs, given that the regression correction relies on the observed loglinear fractionation of different isotope pairs and does not require both isotope ratios to undergo EMF. We expect that the analytical protocol and fundamental insights gained in this study are applicable to a wide range of other isotope measurements with MC-ICP-MS.
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    Nitrous oxide (N 2 O) in Macquarie Harbour, Tasmania (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-20
    Description: Fjord-like estuaries are hotspots of biogeochemical cycling due to steep physicochemical gradients. The spatiotemporal distribution of nitrous oxide (N2O) within many of these systems is poorly described, especially in the southern hemisphere. The goal of this study is to describe the spatiotemporal distribution of N2O within a southern hemisphere fjord-like estuary, describe the main environmental drivers of this distribution, the air/sea flux of N2O, and the main drivers of N2O production. Cruises were undertaken in Macquarie Harbour, Tasmania to capture N2O concentrations and water column physicochemical profiles in winter (July 2022), spring (October 2022), summer (February 2023), and autumn (April 2023). N2O samples were collected at one depth at system end members, and at 5 depths at 4 stations within the harbour. Results indicate that N2O is consistently supersaturated (reaching 170 % saturation) below the system’s freshwater lens where oxygen concentrations are often hypoxic, but infrequently anoxic. In the surface lens, levels of N2O saturation vary with estimated river flow and with proximity to the system’s main freshwater endmember. The linear relationship between AOU and ΔN2O saturation indicates that nitrification is the process generating N2O in the system. When river flow was high (July and October 2022), surface water N2O was undersaturated (as low as 70 %) throughout most of the harbour. When river flow was low (February and April 2023) N2O was observed to be supersaturated at most stations. Calculated air/sea fluxes of N2O indicated that the system is generally a source of N2O to the atmosphere under weak river flow conditions and a sink during strong river flow conditions. The diapycnal flux was a minor contributor to surface water N2O concentrations, and subhalocline N2O is intercepted by the riverine surface lens and transported out of the system to the ocean during strong river flow conditions. In a changing climate, Western Tasmania is expected to receive higher winter rainfall and lower summer rainfall which may augment the source and sink dynamics of this system by enhancing the summer / autumn efflux of N2O to the atmosphere. This study is the first to report observations of N2O distribution, generation processes, and estimated diapycnal / surface N2O fluxes from this system.
    Type: Article , NonPeerReviewed
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  • 98
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    Benchmarking the accuracy of higher-order particle methods in geodynamic models of transient flow (2024)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-06-20
    Description: Numerical models are a powerful tool for investigating the dynamic processes in the interior of the Earth and other planets, but the reliability and predictive power of these discretized models depends on the numerical method as well as an accurate representation of material properties in space and time. In the specific context of geodynamic models, particle methods have been applied extensively because of their suitability for advection-dominated processes and have been used in applications such as tracking the composition of solid rock and melt in the Earth's mantle, fluids in lithospheric- and crustal-scale models, light elements in the liquid core, and deformation properties like accumulated finite strain or mineral grain size, along with many applications outside the Earth sciences.There have been significant benchmarking efforts to measure the accuracy and convergence behavior of particle methods, but these efforts have largely been limited to instantaneous solutions, or time-dependent models without analytical solutions. As a consequence, there is little understanding about the interplay of particle advection errors and errors introduced in the solution of the underlying transient, nonlinear flow equations. To address these limitations, we present two new dynamic benchmarks for transient Stokes flow with analytical solutions that allow us to quantify the accuracy of various advection methods in nonlinear flow. We use these benchmarks to measure the accuracy of our particle algorithm as implemented in the ASPECT geodynamic modeling software against commonly employed field methods and analytical solutions. In particular, we quantify if an algorithm that is higher-order accurate in time will allow for better overall model accuracy and verify that our algorithm reaches its intended optimal convergence rate. We then document that the observed increased accuracy of higher-order algorithms matters for geodynamic applications with an example of modeling small-scale convection underneath an oceanic plate and show that the predicted place and time of onset of small-scale convection depends significantly on the chosen particle advection method.Descriptions and implementations of our benchmarks are openly available and can be used to verify other advection algorithms. The availability of accurate, scalable, and efficient particle methods as part of the widely used open-source code ASPECT will allow geodynamicists to investigate complex time-dependent geodynamic processes such as elastic deformation, anisotropic fabric development, melt generation and migration, and grain damage.
    Type: Article , PeerReviewed
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  • 99
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    Comprehensive molecular‐isotopic characterization of archaeal lipids in the Black Sea water column and underlying sediments (2024)
    Wiley
    Details
    Publication Date: 2024-06-20
    Description: The Black Sea is a permanently anoxic, marine basin serving as model system for the deposition of organic-rich sediments in a highly stratified ocean. In such systems, archaeal lipids are widely used as paleoceanographic and biogeochemical proxies; however, the diverse planktonic and benthic sources as well as their potentially distinct diagenetic fate may complicate their application. To track the flux of archaeal lipids and to constrain their sources and turnover, we quantitatively examined the distributions and stable carbon isotopic compositions (delta 13C) of intact polar lipids (IPLs) and core lipids (CLs) from the upper oxic water column into the underlying sediments, reaching deposits from the last glacial. The distribution of IPLs responded more sensitively to the geochemical zonation than the CLs, with the latter being governed by the deposition from the chemocline. The isotopic composition of archaeal lipids indicates CLs and IPLs in the deep anoxic water column have negligible influence on the sedimentary pool. Archaeol substitutes tetraether lipids as the most abundant IPL in the deep anoxic water column and the lacustrine methanic zone. Its elevated IPL/CL ratios and negative delta 13C values indicate active methane metabolism. Sedimentary CL- and IPL-crenarchaeol were exclusively derived from the water column, as indicated by non-variable delta 13C values that are identical to those in the chemocline and by the low BIT (branched isoprenoid tetraether index). By contrast, in situ production accounts on average for 22% of the sedimentary IPL-GDGT-0 (glycerol dibiphytanyl glycerol tetraether) based on isotopic mass balance using the fermentation product lactate as an endmember for the dissolved substrate pool. Despite the structural similarity, glycosidic crenarchaeol appears to be more recalcitrant in comparison to its non-cycloalkylated counterpart GDGT-0, as indicated by its consistently higher IPL/CL ratio in sediments. The higher TEX86, CCaT, and GDGT-2/-3 values in glacial sediments could plausibly result from selective turnover of archaeal lipids and/or an archaeal ecology shift during the transition from the glacial lacustrine to the Holocene marine setting. Our in-depth molecular-isotopic examination of archaeal core and intact polar lipids provided new constraints on the sources and fate of archaeal lipids and their applicability in paleoceanographic and biogeochemical studies.
    Type: Article , PeerReviewed
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  • 100
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    Extending the Sustainable Development Goals to 2050 — a road map [comment] (2024)
    In:  Nature
    Details
    Publication Date: 2024-06-20
    Description: The world should redouble its efforts on the SDGs, not abandon them. Here’s how to progress the United Nations’ agenda towards 2050.
    Language: English
    Type: info:eu-repo/semantics/article
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