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  • 101
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    Alfred-Wegener-Institut
    In:  Alfred-Wegener-Institut, List auf Sylt, Germany, 2 pp.
    Publication Date: 2019-02-04
    Description: Wochenbericht AL519-1 (28.01.-03.02.2019) [Alkor]
    Type: Report , NonPeerReviewed
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  • 102
    Publication Date: 2019-02-14
    Description: Extratropical volcanic eruptions are commonly thought to be less effective at driving large-scale surface cooling than tropical eruptions. However, recent minor extratropical eruptions have produced a measurable climate impact, and proxy records suggest that the most extreme Northern Hemisphere cold period of the Common Era was initiated by an extratropical eruption in 536 CE. Using ice-core-derived volcanic stratospheric sulfur injections and Northern Hemisphere summer temperature reconstructions from tree rings, we show here that in proportion to their estimated stratospheric sulfur injection, extratropical explosive eruptions since 750 CE have produced stronger hemispheric cooling than tropical eruptions. Stratospheric aerosol simulations demonstrate that for eruptions with a sulfur injection magnitude and height equal to that of the 1991 Mount Pinatubo eruption, extratropical eruptions produce time-integrated radiative forcing anomalies over the Northern Hemisphere extratropics up to 80% greater than tropical eruptions, as decreases in aerosol lifetime are overwhelmed by the enhanced radiative impact associated with the relative confinement of aerosol to a single hemisphere. The model results are consistent with the temperature reconstructions, and elucidate how the radiative forcing produced by extratropical eruptions is strongly dependent on the eruption season and sulfur injection height within the stratosphere.
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  • 103
    Publication Date: 2019-02-22
    Description: Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity in the last years. We investigated mating activity of Humboldt squid in the Gulf of California in 2013, 2014, and 2015 by quantifying spermatangia deposited in the tissue of the buccal area. In 2015, we encountered the smallest mean mantle length of mature specimens recorded to date in the Gulf of California. In all years, numerous males were encountered that had been mated by other males. Spermatangia in males were deposited on the tissue in similar numbers and in the same location as normally occurs in females (the buccal area), suggesting that male-to-male mating behaviour is similar to male-to-female. This behaviour is referred to as same-sex sexual behaviour and has been described for various taxa, including other cephalopods. Overall similarity in mating frequency between males and females and in body size of mated individuals (in 2015) suggests non-discriminative and brief encounters with body size being a cue for mating. This mating strategy may be beneficial for males, as Humboldt squid live in groups where competition for mates is likely high. The energetic costs of male-to-male mating events may be counterbalanced by the fitness profits of indiscriminate mating behaviour.
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  • 104
    Publication Date: 2019-04-11
    Description: Radiative forcing from volcanic aerosol impacts surface temperatures; however, the background climate state also affects the response. A key question thus concerns whether constraining forcing estimates is more important than constraining initial conditions for accurate simulation and attribution of posteruption climate anomalies. Here we test whether different realistic volcanic forcing magnitudes for the 1815 Tambora eruption yield distinguishable ensemble surface temperature responses. We perform a cluster analysis on a superensemble of climate simulations including three 30-member ensembles using the same set of initial conditions but different volcanic forcings based on uncertainty estimates. Results clarify how forcing uncertainties can overwhelm initial-condition spread in boreal summer due to strong direct radiative impact, while the effect of initial conditions predominate in winter, when dynamics contribute to large ensemble spread. In our setup, current uncertainties affecting reconstruction-simulation comparisons prevent conclusions about the magnitude of the Tambora eruption and its relation to the “year without summer.”
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  • 105
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    Copernicus Publications (EGU)
    In:  Atmospheric Chemistry and Physics, 19 (3). pp. 1819-1834.
    Publication Date: 2019-02-22
    Description: Eddy covariance measurements show gas transfer velocity suppression at medium to high wind speed. A wind-wave interaction described by the transformed Reynolds number is used to characterize environmental conditions favoring this suppression. We take the transformed Reynolds number parameterization to review the two most cited wind speed gas transfer velocity parameterizations: Nightingale et al. (2000) and Wanninkhof (1992, 2014). We propose an algorithm to adjust k values for the effect of gas transfer suppression and validate it with two directly measured dimethyl sulfide (DMS) gas transfer velocity data sets that experienced gas transfer suppression. We also show that the data set used in the Nightingale 2000 parameterization experienced gas transfer suppression. A compensation of the suppression effect leads to an average increase of 22% in the k vs. u relationship. Performing the same correction for Wanninkhof 2014 leads to an increase of 9.85 %. Additionally, we applied our gas transfer suppression algorithm to global air-sea flux climatologies of CO2 and DMS. The global application of gas transfer suppression leads to a decrease of 11% in DMS outgassing. We expect the magnitude of Reynolds suppression on any global air-sea gas exchange to be about 10%
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  • 106
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    In:  , 2 pp.
    Publication Date: 2019-02-27
    Description: 18/2/2019-24/2/2019
    Type: Report , NonPeerReviewed
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  • 107
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    In:  , 2 pp.
    Publication Date: 2019-02-25
    Description: 17.-25.02.2019
    Type: Report , NonPeerReviewed
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  • 108
    Publication Date: 2019-02-27
    Description: Predictive species distribution models are mostly based on statistical dependence between environmental and distributional data and therefore may fail to account for physiological limits and biological interactions that are fundamental when modelling species distributions under future climate conditions. Here, we developed a state-of-the-art method integrating biological theory with survey and experimental data in a way that allows us to explicitly model both physical tolerance limits of species and inherent natural variability in regional conditions and thereby improve the reliability of species distribution predictions under future climate conditions. By using a macroalga-herbivore association (Fucus vesiculosus - Idotea balthica) as a case study, we illustrated how salinity reduction and temperature increase under future climate conditions may significantly reduce the occurrence and biomass of these important coastal species. Moreover, we showed that the reduction of herbivore occurrence is linked to reduction of their host macroalgae. Spatial predictive modelling and experimental biology have been traditionally seen as separate fields but stronger interlinkages between these disciplines can improve species distribution projections under climate change. Experiments enable qualitative prior knowledge to be defined and identify cause-effect relationships, and thereby better foresee alterations in ecosystem structure and functioning under future climate conditions that are not necessarily seen in projections based on non-causal statistical relationships alone.
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  • 109
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    AtlantOS
    In:  AtlantOS Deliverable, D8.10 . AtlantOS, 11 pp.
    Publication Date: 2019-03-11
    Description: This task will use outputs from the Copernicus Marine Environment Monitoring Service (CMEMS) to develop a system for ship routing hazard mapping. Starting from knowledge of the environmental fields affecting vessel seakeeping, the system will estimate hazard and cost associated to known routes in the Atlantic Ocean. The system will employ model analysis or reanalysis of sea state (wave height, period, and direction), hydrodynamics (near surface ocean currents), and meteorological (wind) models. The system will produce an objective route hazard assessment, based on UNIBO experience in hazard mapping and probabilistic approaches. The investigated routes will be selected based on the most relevant ones, according to the AIS (Automatic Information System) density maps. In particular, the existing CMCC ship routing code (VISIR) will be first of all validated through inter-­comparison with analytical benchmarks and other published models. VISIR’s functionalities will then be extended for optimizing the operational costs (bunker) of large ocean-­going vessels sailing along routes compliant with IMO safety recommendations. The same approach will be extended to computation of vessel operational costs along the route. This information will build up a database, queried by the end-­user through a graphical interface for visualizing customized maps of route hazard and cost for user provided parameters [D8.10]. The fitness of AtlantOS for ship routing will be analyzed with a dedicated report [D8.14].
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 110
    Publication Date: 2019-04-16
    Description: Atmospheric deposition can be an important source of nutrients and trace metals to oligotrophic alpine lakes, affecting their biogeochemistry. We measured trace metal concentrations and lead (Pb) isotope ratios in lake water, river water, ground water, and aerosol total suspended particles (TSP), as well as nutrient (NO 3 − , NH 4 + , PO 4 3− ) concentrations in TSP in the Tahoe Basin. The contribution of TSP deposition to the lake trace metal budget was assessed. Our results show seasonality in TSP and associated trace metal concentrations with higher concentrations during Oct – April. However, trace metal solubilities are higher during May – Sept, resulting in a higher contribution of soluble trace metals to the lake water. The source of most of the trace metals in TSP in the Lake Tahoe Basin is mineral dust; however, Zn, Cu, and Cd also have an anthropogenic origin. Among major nutrients, NO 3 − concentrations are slightly higher during Oct – April, while NH 4 + and soluble reactive phosphorus (SRP) are higher during May – Sept. The distributions of trace metal concentrations and Pb isotopic ratios are homogenous throughout the lake water column, suggesting that the residence time of the trace metals in the lake is longer than the lake water mixing time. The contribution of atmospheric TSP deposition to the upper 20 m of lake water trace metal inventory is low, ranging from 0.03% for V to 5.7% for Mn. A triple-isotopes plot of Pb indicates that riverine and groundwater inputs are the major Pb sources, but aerosols still contribute some Pb to the lake. This article is part of a special issue entitled: Conway GEOTRACES - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.
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  • 111
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    In:  [Poster] In: 79. Annual meeting of the German Geophysical Society (DGG), 04.-07.03.2019, Braunschweig, Germany .
    Publication Date: 2019-04-12
    Description: OBS data are exposed to additional noise sources like tilt and compliance. We show that the data can be enhanced prior to the usage of standardised land seismology techniques, such as ambient noise tomography. We do this by estimating group velocities before and after enhancing the signal. This project is part of AlpArray and aims to improve the understanding of the proposed subduction polarity change between the Alpine and Apennine subduction.
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  • 112
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    In:  , 2 pp.
    Publication Date: 2019-03-18
    Description: Dritter Wochenbericht der FS Poseidon Expedition POS 533 - AIMAC Atmosphäre-Ozean-Inseln-Biogeochemische Wechselwirkungen in den Makaronesischen Archipelen der Kap Verden, der Kanaren und Madeira (11.03.-17.03.2019) Mindelo (Kap Verden) - Las Palmas (Gran Canaria) - Funchal (Madeira) - Las Palmas
    Type: Report , NonPeerReviewed
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  • 113
    Publication Date: 2019-03-27
    Type: Thesis , NonPeerReviewed
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  • 114
    Publication Date: 2019-04-04
    Description: We quantify the oceanic sink for anthropogenic carbon dioxide (CO 2 ) over the period 1994 to 2007 by using observations from the global repeat hydrography program and contrasting them to observations from the 1990s. Using a linear regression–based method, we find a global increase in the anthropogenic CO 2 inventory of 34 ± 4 petagrams of carbon (Pg C) between 1994 and 2007. This is equivalent to an average uptake rate of 2.6 ± 0.3 Pg C year −1 and represents 31 ± 4% of the global anthropogenic CO 2 emissions over this period. Although this global ocean sink estimate is consistent with the expectation of the ocean uptake having increased in proportion to the rise in atmospheric CO 2 , substantial regional differences in storage rate are found, likely owing to climate variability–driven changes in ocean circulation.
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  • 115
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    Senckenberg am Meer
    In:  Senckenberg am Meer, Wilhelmshaven, Germany, 2 pp.
    Publication Date: 2019-04-01
    Description: (24.03. – 31.03.2019)
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  • 116
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    Society of Economic Geologists
    In:  Economic Geology, 114 (2). pp. 397-400.
    Publication Date: 2019-04-09
    Description: The transport and deposition of gold from colloidal suspensions in hydrothermal fluids has been a persistent theme in ore deposits research. Studies of active geothermal systems show that a complete model of gold transport must include both dissolved and particulate forms. However, samples of the hydrothermal fluids are commonly spiked with aqua regia after collection in order to put any solids back into solution, thus preventing a quantitative assessment of the particle load. Although attempts have been made to filter the solids, gold nanoparticles (Au NPs) will mostly pass the 0.2-µm filters that are in common use, and a simple technique for analyzing suspended particles in the liquids has been lacking. In this study, we demonstrate how time-resolved acquisition of mass 197 in a conventional inductively coupled plasma-mass spectrometer (ICP-MS) can be used to detect and measure Au NPs in the filtered liquids, with an example of well-characterized fluids from the Reykjanes geothermal field on Iceland. The technique allows for precise monitoring of the solution as it is introduced into the plasma with the capability of identifying individual particles carried in suspension. Results show that Au particles passing the 0.2-µm filters are abundant in the studied samples, and measurements of the individual particles can be used to determine their size. The experiment highlights the potential of emerging ICP-MS techniques, including very fast data acquisition and multielement analysis of single particles in timeof-flight mode, for characterization of NPs in hydrothermal fluids.
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  • 117
    Publication Date: 2019-04-02
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  • 118
    Publication Date: 2019-03-28
    Description: Highlights • Geochronology and provenance analysis from the Cosinas and Machiques Basins show a new tectono-sedimentological evolution. • Multiproxy analysis are required to understand tectono-sedimentological evolution in extensional basins. • Paleogeographic evolution shows a closer connection between Maya and Guajira blocks since the early Jurassic. Abstract Jurassic extensional basins developed along the northwestern margin of South America during the break-up of Pangea. Presently, these basins are dispersed in several tectonic blocks of the northern Andes and Mexico, hindering reconstruction of western equatorial Pangea before break-up. This is the case of the Cosinas Basin (Guajira block) and the Machiques Basin (Perijá Range), in northern Colombia, which are filled by Jurassic sedimentary and volcano-sedimentary successions. Autochthonous and para-autochthonous hypotheses on the origin of this basins have been proposed. The purpose of this research is to document the sedimentological evolution, depositional age (Sr-isotope + U-Pb geochronology), sediment provenance and paleogeography of the Cosinas and Machiques basins in order to constrain whether these basins formed within a single extensional margin or they formed as extensional basins in different tectonic blocks. Volcanic detrital zircon U-Pb ages documented in La Quinta Formation in the Machiques Basin and at the base of Rancho Grande Formation in the Cosinas Basin suggest that extensional basins were active in Early Jurassic time. However, a significant difference exists in their subsequent history. Whereas in the Machiques Basin dominates the accumulation of Lower and Middle Jurassic volcanoclastic deposits with abrupt lateral thickness changes, accumulation in the Cosinas Basin is dominantly of siliciclastic strata, with the record of two major marine incursions in Late Jurassic time. Integration of provenance results indicates that the Santander Massif supplied sediments to the Machiques Basin. In contrast, Middle to Upper Jurassic sandstones of the Cosinas Basin document unroofing of basement blocks that include metamorphic, sedimentary and plutonic rocks from the Guajira and Maya blocks. The similarity in age and composition of pre-Jurassic rocks in northwestern South America and the so-called peri-Gondwana blocks in the Mexican subcontinent (i.e., Maya and Oaxaquia blocks) challenge the use of detrital zircon population as an indicator of the autochthonous or para-autochthonous origin of the Guajira block. Large uncertainty of paleomagnetic results, and the lack of constraints for the time magnetization acquisition preclude estimating paleolatitudes for the Guajira block in Jurassic time but support previous interpretation of ca. 70°-90° clockwise rotation of the Guajira block relative to stable South America craton. Our preferred paleogeography considers that the Cosinas and Machiques basins were close to each other along the western continental margin of Pangea during the onset of extension in Early Jurassic time. The change from continental to marine depositional environments in Middle to Late Jurassic time along the Cosinas Basin, which have not been identified in the Machiques Basin or other autochthonous Jurassic basins in northwestern South America, allow us to propose that these blocks were separated during the Callovian - Tithonian interval, with the Cosinas Basin remaining closer to a conjugate Mexican margin, that we interpret as the Maya block. Collision of the Guajira block with the South American margin occurred near the Jurassic-Cretaceous boundary, as documented by deformation of Jurassic units previous to deposition of Berriasian strata in the Guajira block.
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  • 119
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    Pleiades Publishing, Springer
    In:  Lithology and Mineral Resources, 54 (2). pp. 79-92.
    Publication Date: 2019-04-02
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  • 120
    Publication Date: 2019-04-03
    Description: Sediments were sampled at nine stations on a transect across a 7–10 m thick Holocene mud layer in Aarhus Bay, Denmark, to investigate the linkages between CH4 dynamics and the rate and depth distribution of organic matter degradation. High-resolution sulfate reduction rates determined by tracer experiments (35S-SRR) decreased by several orders of magnitude down through the mud layer. The rates showed a power law dependency on sediment age: SRR (nmol cm−3 d−1) = 106.18 × Age−2.17. The rate data were used to independently quantify enhanced SO42− transport by bioirrigation. Field data (SO42–, TCO2, T13CO2, NH4+ and CH4 concentrations) could be simulated with a reaction-transport model using the derived bioirrigation rates and assuming that the power law was continuous into the methanogenic sediments below the sulfate-methane transition zone (SMTZ). The model predicted an increase in anaerobic organic carbon mineralization rates across the transect from 2410 to 3540 nmol C cm−2 d−1 caused by an increase in the sediment accumulation rate. Although methanogenesis accounted for only ∼1% of carbon mineralization, a large relative increase in methanogenesis along the transect led to a considerable shallowing of the SMTZ from 428 to 257 cm. Methane gas bubbles appeared once a threshold in the sedimentation accumulation rate was surpassed. The 35S-measured SRR data indicated active sulfate reduction throughout the SO42− zone whereas quasi-linear SO42− gradients over the same zone indicated insignificant sulfate reduction. This apparent inconsistency, observed at all stations, was reconciled by considering the transport of SO42− into the sediment by bioirrigation, which accounted for 94 ± 2% of the total SO42− flux across the sediment-water interface. The SRR determined from the quasi-linear SO42− gradients were two orders of magnitude lower than measured rates. We conclude that models solely based on SO42− concentration gradients will not capture high SRRs at the top of the sulfate reduction zone if they do not properly account for (i) SO42− influx by bioirrigation, and/or (ii) the continuity of organic matter reactivity with sediment depth or age.
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  • 121
    Publication Date: 2019-04-02
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  • 122
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    In:  , 2 pp.
    Publication Date: 2019-04-01
    Description: TRR181 Cruise Poseidon 533/2 25. March - 1. April 2019 1. Weekly report!
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  • 123
    Publication Date: 2019-04-03
    Description: Highlights • Novel approach to constrain past export production using Ba isotopes. • Ba isotopes improve reliability of the Ba accumulation productivity proxy. • Higher productivity during PETM recovery contributed to rapid carbon sequestration. Abstract The Paleocene–Eocene thermal maximum (PETM; ∼56 Ma) was a transient global warming event associated with a huge perturbation to the global carbon cycle. Changes in marine biological productivity may have contributed to the rapid recovery from this climate change event, by driving the burial of inorganic and organic carbon. Disagreement between proxy reconstructions, however, makes the response of biological productivity to climatic changes experienced during the PETM uncertain. Accumulation of non-detrital barium (Ba) in marine sediments is a commonly used proxy for export production. This proxy however can be compromised by artifacts resulting from dilution and changes in barite preservation, issues that have been debated for its application to sediments deposited during the PETM. Here we present a new approach to address these limitations, by combining non-detrital Ba accumulation with Ba isotope data for marine PETM sediments. Observed positive correlation between these variables is consistent with their control by local changes in export production. These results help resolve previous discrepancies between productivity reconstructions, and indicate export production at sites in the Southern Ocean and South Atlantic decreased or remained unchanged following the PETM onset, followed by an increase to maximum values in the PETM recovery period. This increase in export production coincides with elevated carbonate accumulation rates, representing an important mode of carbon sequestration. These new constraints therefore support the idea that increased production and export of calcifying nannoplankton, perhaps driven by changes in ocean stratification and/or terrestrial runoff, played an important role in rapid recovery from the PETM. This work also demonstrates the utility of sedimentary Ba isotope compositions for understanding past changes in the marine carbon cycle.
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  • 124
    Publication Date: 2019-04-03
    Description: Highlights • Exposure ages that constrain ice sheet thickness collated from an online database. • Thinning rates are reconstructed from 23 sites across Antarctica. • Palaeo-thinning rates are comparable to modern observations. • Wide-spread thinning during the Holocene, but after Meltwater Pulse 1A. Abstract Constraining Antarctic ice sheet evolution provides a way to validate numerical ice sheet models that aid predictions of sea-level rise. In this paper we collate cosmogenic exposure ages from exposed nunataks in Antarctica that have been used, or have the potential to be used, to constrain rates of thinning of the Antarctic Ice Sheets since the Last Glacial Maximum. We undertake quality control of the data and adopt a Bayesian approach to outlier detection. Past thinning rates are modelled by Monte Carlo linear regression analysis. We present thinning rates from 23 sites across Antarctica. The resulting data set is the first Antarctic-wide collation of past ice sheet thinning rates and provides an empirical starting point for future model-data comparisons. Palaeo-thinning rates are spatially variable with high rates appearing to correlate to areas of contemporary rapid changes. On centennial timescales past thinning rates are comparable to modern day observations implying that modern day thinning has the potential to persist for centuries in numerous parts of Antarctica. The onset of abrupt thinning from all sites post-dates Meltwater Pulse 1A suggesting that its source region(s) are distal to areas where exposure age constraints on ice surface geometry exist.
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  • 125
    Publication Date: 2019-04-03
    Description: Highlights • Robust increase in silt size at 5 ka reflects increased flow of Labrador Sea Water. • Ice-rafted debris likely affects on the Labrador Slope during the last deglacial. • End member modeling and corrections provide insight into deglacial sediments. Abstract The Labrador Sea is a vital region for the Atlantic Meridional Overturning Circulation (AMOC), where overflow waters from the Nordic Seas mix with locally produced Labrador Sea Water (LSW), before exiting to the interior of the Atlantic Ocean. The dynamical sedimentary proxy of mean sortable silt size ( ) can give information on past changes in deep water circulation speed and the strength of AMOC. We have produced records from two core sites at depths between 1500 and 2000 m on the continental slope east of Newfoundland, to reconstruct changes in intermediate depth water circulation speed, including Glacial North Atlantic Intermediate Water and Labrador Sea Water over the past 22,000 years. Increases in appear to coincide with much of the deglaciation as well as the mid-late Holocene. End-member modeling suggests that ice-rafted debris (IRD) is an important factor in interpreting during the deglaciation. We find that a robust increase in is likely unrelated to IRD during the past 5 ka, and probably reflects increased flow at intermediate depths due to local production of LSW strengthening as Nordic Seas overflows weakened at this depth. Our results highlight both the complications of producing records in IRD-rich, slope environments and the promise that this proxy nevertheless has for reconstructing dynamical changes in deep ocean currents.
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  • 126
    Publication Date: 2019-04-03
    Description: Highlights • Volcanic activity of Harrat Uwayrid (NW Arabia) lasted from 8.2 to 0.3 Ma. • Alkali olivine basalts are followed by basanites, tephrites and tephriphonolites. • Sr-Nd-Pb isotopic ratios of all volcanic rocks suggest a PREMA source. • Different degrees of partial melting of amphibole-garnet-spinel lherzolite • Lithospheric mantle source rather than asthenosphere or plume-type mantle Abstract The volcanic field of Harrat ar Rahah-’Uwayrid (NW Saudi Arabia) consists of an older plateau basalt sequence that overlies Cambrian sandstone and younger cinder cones with smaller flows that are concentrated in the central part of this field. Petrographic and whole rock geochemical data indicate that the older plateau basalts are alkali olivine basalts, while the younger volcanic products are basanites and tephrites with some phonotephrites and tephriphonolites. KAr model ages on 22 bulk-rock samples were obtained for variable grain size fractions (125–250, 250–500 μm). These dates range from 8.2 to 0.34 Ma, whereby three phases of volcanic activity during the Upper Miocene, Pliocene and Quaternary can be distinguished. Sr-Nd-Pb isotopic ratios are similar for all age groups with 87Sr/86Sr = 0.70307–0.70324, 143Nd/144Nd = 0.512912–0.512957, 206Pb/204Pb = 19.360–19.717, 207Pb/204Pb = 15.603–15.633 and 208Pb/204Pb = 39.083–39.521 (present-day ratios are indistinguishable from calculated initial ratios) suggesting that chemical differences among the lavas were probably produced by different degrees of partial melting rather than by different source compositions. Trace element ratios indicate an origin of all volcanics by small degrees of partial melting of amphibole-spinel-garnet peridotite. Geochemical and isotopic data of the Harrat ar Rahah-’Uwayrid are similar to those from the small volcanic fields of Harrat Kura (about 200 km SSE of Harrat al ‘Uwayrid) and of Wadi Jizan in SW Saudi Arabia, but clearly more enriched than those of the volcanic fields that are located in the more central parts of the eastern shoulder of the Red Sea Rift. The lithospheric thickness underneath Harrat ar Rahah-’Uwayrid is estimated to about 60 km based on published results from seismic tomography. Our data support the model that the metasomatized lithospheric mantle was the primary source of the magmas, while the asthenospheric mantle or a plume-type component played an unsignificant role. The composition of the lithospheric mantle source was similar to prevalent mantle (PREMA). There is no need to postulate the participation of a HIMU component and/or enriched mantle components (EM-1, EM-2) in the source of the investigated magmas.
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  • 127
    Publication Date: 2019-04-04
    Description: Global warming is already affecting the oceans through changes in water temperature, acidification, oxygen content and sea level rise, amongst many others. These changes are having multiple effects on marine species worldwide, with subsequent impacts on marine fisheries, peoples' livelihoods and food security. This work presents a review of the recent literature on the current and projected impacts of climate change on Canada's Pacific marine ecosystem. We find that there is an increasing number of studies in British Columbia focusing on changes in ocean conditions and marine species responses under climate change, including an emerging literature on the socio-economic impacts of these changes considered to be a knowledge gap. According to the literature, it is well established that ocean temperatures are increasing over the long-term, especially, in southern areas of British Columbia. Warming trends are increasing in the spring and are strongest in summer. However, there are important uncertainties regarding other climate drivers, such as oxygen concentration and acidification, stemming mainly from the insufficiency of data. Pacific salmon, elasmobranchs, invertebrates and rockfishes are amongst the most vulnerable species groups to climate change in British Columbia. Also, shifts in stock distribution and fish abundance under climate change may have a significant impact on fish supply affecting the livelihoods and food security of some British Columbians. The magnitude of these impacts is likely to vary according to a latitudinal gradient, with southern coastal areas being more affected than northern and central areas; challenging multiple areas of governance, such as equity and fishing access amongst First Nations; and institutional arrangements for transboundary stocks between the U.S. and Canada.
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  • 128
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    In:  , 2 pp.
    Publication Date: 2019-04-17
    Description: Mindelo-Point a Pitre 03.-07.04.2019
    Type: Report , NonPeerReviewed
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  • 129
    Publication Date: 2019-03-29
    Description: Marine transform faults and associated fracture zones (MTFFZs) cover vast stretches of the ocean floor, where they play a key role in plate tectonics, accommodating the lateral movement of tectonic plates and allowing connections between ridges and trenches. Together with the continental counterparts of MTFFZs, these structures also pose a risk to human societies as they can generate high magnitude earthquakes and trigger tsunamis. Historical examples are the Sumatra-Wharton Basin Earthquake in 2012 (M8.6) and the Atlantic Gloria Fault Earthquake in 1941 (M8.4). Earthquakes at MTFFZs furthermore open and sustain pathways for fluid flow triggering reactions with the host rocks that may permanently change the rheological properties of the oceanic lithosphere. In fact, they may act as conduits mediating vertical fluid flow and leading to elemental exchanges between Earth’s mantle and overlying sediments. Chemicals transported upward in MTFFZs include energy substrates, such as H2 and volatile hydrocarbons, which then sustain chemosynthetic, microbial ecosystems at and below the seafloor. Moreover, up- or downwelling of fluids within the complex system of fractures and seismogenic faults along MTFFZs could modify earthquake cycles and/or serve as “detectors” for changes in the stress state during interseismic phases. Despite their likely global importance, the large areas where transform faults and fracture zones occur are still underexplored, as are the coupling mechanisms between seismic activity, fluid flow, and life. This manuscript provides an interdisciplinary review and synthesis of scientific progress at or related to MTFFZs and specifies approaches and strategies to deepen the understanding of processes that trigger, maintain, and control fluid flow at MTFFZs.
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  • 130
    Publication Date: 2019-04-11
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 131
    Publication Date: 2019-04-16
    Description: Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Husbandry strategies to reduce biofouling can involve avoidance, prevention, and treatment. In this way, the type of rope used to collect spat or grow bivalves may prevent or reduce fouling by particularly harmful species but remains largely untested. Further, while a range of eco-friendly control methods exist, their effect on widespread, common biofoulers is poorly known. We tested biofouling accumulation and spat collection for seven commercially used ropes, and evaluated treatments of ambient and heated seawater, acetic and citric acid, and combinations of both applied across a range of exposure times to two commercially grown shellfish (Mytilus galloprovincialis and Ostrea angasi) and three biofouling species (Ectopleura crocea, Ciona intestinalis and Styela clava). Rope types differed significantly in terms of fouling rates and spat collection, with specific rope types clearly advantageous, despite not being used commercially in our study area. Treatments proved variably successful, with E. crocea highly susceptible to all treatments, Ciona intestinalis moderately susceptible, and Styela clava relatively resistant. Excluding S. clava, efficacious treatments were attainable that did not adversely affect shellfish. Combining heat and acid treatments were more successful than individual treatments and provide a useful avenue for further trials. This study provides baseline evidence for treatment efficacy that will tailor longer-term, field trials to validate and streamline biofouling treatments in shellfish aquaculture.
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  • 132
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    In:  , 2 pp.
    Publication Date: 2019-04-15
    Description: 7‐13. April 2019
    Type: Report , NonPeerReviewed
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  • 133
    Publication Date: 2019-04-15
    Description: Genetic data have great potential for improving fisheries management by identifying the fundamental management units—that is, the biological populations—and their mixing. However, so far, the number of practical cases of marine fisheries management using genetics has been limited. Here, we used Atlantic cod in the Baltic Sea to demonstrate the applicability of genetics to a complex management scenario involving mixing of two genetically divergent populations. Specifically, we addressed several assumptions used in the current assessment of the two populations. Through analysis of 483 single nucleotide polymorphisms (SNPs) distributed across the Atlantic cod genome, we confirmed that a model of mechanical mixing, rather than hybridization and introgression, best explained the pattern of genetic differentiation. Thus, the fishery is best monitored as a mixed-stock fishery. Next, we developed a targeted panel of 39 SNPs with high statistical power for identifying population of origin and analyzed more than 2,000 tissue samples collected between 2011 and 2015 as well as 260 otoliths collected in 2003/2004. These data provided high spatial resolution and allowed us to investigate geographical trends in mixing, to compare patterns for different life stages and to investigate temporal trends in mixing. We found similar geographical trends for the two time points represented by tissue and otolith samples and that a recently implemented geographical management separation of the two populations provided a relatively close match to their distributions. In contrast to the current assumption, we found that patterns of mixing differed between juveniles and adults, a signal likely linked to the different reproductive dynamics of the two populations. Collectively, our data confirm that genetics is an operational tool for complex fisheries management applications. We recommend focussing on developing population assessment models and fisheries management frameworks to capitalize fully on the additional information offered by genetically assisted fisheries monitoring.
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  • 134
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    In:  , 2 pp.
    Publication Date: 2019-04-17
    Description: Mindelo - Point a Pitre 08.-14.04.2019
    Type: Report , NonPeerReviewed
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  • 135
    Publication Date: 2019-04-26
    Description: An interactive (multi-access) global identification key (OncIdent) has been developed for the pelagic marine microcopepod family Oncaeidae and made accessible online. Details of the general approach and development of the key are given in Bottger-Schnack and Schnack (J Nat Hist 49:2727-2741, 2015). After beta-testing, new additions include illustrations for all species and feature attributes considered, plus a textual summary of each species' feature states in the key. Additional taxonomic notes are given where required, highlighting morphological or molecular genetic peculiarities or problems, with links to large data bases leading directly to more comprehensive information about each species. The present paper briefly reviews the taxonomic background for key construction, summarizes the opportunities and limitations of the current online version OncIdent2.0, and provides guidance for its practical use.
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  • 136
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    Baltic Gender Coordination Office
    In:  Baltic Gender Deliverable, D2.3 . Baltic Gender Coordination Office, Kiel, Germany, 14 pp.
    Publication Date: 2019-04-26
    Description: The report compiles a checklist that will help to maintain contacts with the individuals taking family breaks and for employees returning to regular working conditions afterwards. Binding procedures will be recommended to guarantee a successful career continuation with continuous institutional support.
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 137
    Publication Date: 2019-04-29
    Description: Sponges are one of the most dominant organisms in marine ecosystems. One reason for their success is their association with microorganisms that are besides the host itself responsible for the chemical defence. Sponge abundances have been increasing on coral reefs in the Western Indian Ocean (WIO) and are predicted to increase further with rising anthropogenic impacts on coral reefs. However, there is a paucity of information on chemical ecology of sponges from the WIO and their prokaryotic community composition. We used a combination of Illumina sequencing and a predictive metagenomic analysis to (i) assess the prokaryotic community composition of sponges from Zanzibar, (ii) predict the presence of KEGG metabolic pathways responsible for bioactive compound production and (iii) relate their presence to the degree of observed chemical defence in their respective sponge host. We found that sponges from Zanzibar host diverse prokaryotic communities that are host species-specific. Sponge-species and respective specimens that showed strong chemical defences in previous studies were also predicted to be highly enriched in various pathways responsible for secondary metabolite production. Hence, the combined sequencing and predictive metagenomic approach proved to be a useful indicator for the metabolic potential of sponge holobionts
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  • 138
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    In:  , 4 pp.
    Publication Date: 2019-04-29
    Description: 21.‐27. April 2019
    Type: Report , NonPeerReviewed
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  • 139
    Publication Date: 2019-05-02
    Description: Highlights • New experiments with melt inclusions in olivine at 1200 °C and 300 MPa. • Coupled behavior H2O and SiO2 in inclusions during re-hydration and dehydration. • SiO2 mobility results from formation/destruction of metal vacant olivine. • SiO2-undersaturated arc melt inclusions may originate by dehydration. • New method to assess initial H2O in dehydrated inclusions. Abstract Primary subduction-related magmas build up modern continental crust and counterbalance massive recycling of crustal material into the deep mantle occurring at this tectonic setting. Melt inclusions in Mg-rich olivine are believed to be the best probes of primary subduction-related melts. However, unexpectedly, most of such inclusions are SiO2-undersaturated, in contrast to predominantly SiO2-saturated island-arc rocks. The origin of these melts has been explained by melting of amphibole-bearing pyroxenites in the lower crust or upper mantle. The current models fail, however, to explain the high abundance of SiO2-undersaturated melts as well as their compositional difference with host rocks for the major elements but not for incompatible trace elements. Here we report results from the investigation of rocks and melt inclusions in olivine from Klyuchevskoy volcano in Kamchatka. We show that experimental re-hydration of SiO2-undersaturated melt inclusions in olivine Fo85−90 at 300 MPa pressure and 1200 °C causes a concomitant enrichment of melt in H2O and SiO2 so that re-hydrated inclusions (4–5 wt% H2O) become as silica-saturated as primitive Klyuchevskoy rocks. An experimental dehydration of previously re-hydrated inclusions also resulted in coupled depletion of melt in H2O and SiO2. The estimated stoichiometry of SiO2 and H2O gain/loss is consistent with dissolution/crystallization of metal-defect olivine on inclusion walls. The migration mechanism of water is controlled by hydrogen diffusion in the octahedral metal (Mg, Fe) vacancies through olivine structure as confirmed by FTIR spectroscopy. We conclude that the previously reported SiO2-undersaturated composition of many melt inclusions from hypersthene-normative island-arc rocks can be explained by the coupled loss of up to several weight percent of H2O and SiO2 from the initially trapped primitive SiO2-saturated hydrous melts. Thus, SiO2-undersaturated melt inclusions may not be representative of primitive island-arc magmas. The discovery of the coupled SiO2 and H2O loss from inclusions allowed us to propose a method for reconstruction of the initial water content even for completely dehydrated inclusions. The results of this study may indicate that the majority of primitive island-arc inclusions have not preserved their initial H2O content, and that primary arc melts contain on average ≥4 wt% H2O. The higher H2O concentration in primary arc melts implies the existence of a ‘crustal filter’ controlling the water content, which can be preserved in melt inclusions, and also the lower mantle melting temperatures and higher output H2O fluxes in subduction zones than previously estimated based on direct determination of H2O in potentially dehydrated melt inclusions.
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  • 140
    Publication Date: 2019-05-03
    Description: Over recent decades, the neophyte Fucus evanescens has extended eastwards along the salinity gradient within the Baltic Sea, indicating gradual adaptation to low salinity conditions. To find out whether F. evanescens can migrate further into the Baltic Sea and potentially become a competitor to the native F. vesiculosus, the acclimation potentials of different F. evanescens and F. vesiculosus populations were investigated with respect to habitat salinity. For both species, pigmentation, water content, and photosynthetic rate were measured under laboratory and field conditions. The instantaneous measurement data and incubation experiment did not show clear differences in the measured photosynthetic parameters between different salinity levels (6–20), or between species. Maximum likelihood phylogenetic analyses of the nuclear marker PDI (a putative protein disulfide isomerase) separated F. vesiculosus and F. evanescens into well-defined groups supporting the hypothesis that the two very similar species do not represent different morphotypes of the same species/gene pool. These findings indicate that – at least for the vegetative stage of F. evanescens – salinity may not be a limiting factor for a further spread into the Baltic Sea.
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  • 141
    Publication Date: 2019-05-02
    Description: To model tracer spreading in the ocean, Lagrangian simulations in an offline framework are a practical and efficient alternative to solving the advective–diffusive tracer equations online. Differences in both approaches raise the question of whether both methods are comparable. Lagrangian simulations usually use model output averaged in time, and trajectories are not subject to parameterized subgrid diffusion, which is included in the advection–diffusion equations of ocean models. Previous studies focused on diffusivity estimates in idealized models but could show that both methods yield similar results as long as the deformations-scale dynamics are resolved and a sufficient amount of Lagrangian particles is used. This study compares spreading of an Eulerian tracer simulated online and a cloud of Lagrangian particles simulated offline with velocities from the same ocean model. We use a global, eddy-resolving ocean model featuring 1/20° horizontal resolution in the Agulhas region around South Africa. Tracer and particles were released at one time step in the Cape Basin and below the mixed layer and integrated for 3 years. Large-scale diagnostics, like mean pathways of floats and tracer, are almost identical and 1D horizontal distributions show no significant differences. Differences in vertical distributions, seen in a reduced vertical spreading and downward displacement of particles, are due to the combined effect of unresolved subdaily variability of the vertical velocities and the spatial variation of vertical diffusivity. This, in turn, has a small impact on the horizontal spreading behavior. The estimates of eddy diffusivity from particles and tracer yield comparable results of about 4000 m2 s−1 in the Cape Basin.
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  • 142
    Publication Date: 2019-05-06
    Description: Highlights • Present original 2D/3D seismic data to reveal the geologic setting of a potential gas hydrate prospect off SW Taiwan. • Active fluid flow processes are studied by analyzing water column and seismic data. • A conceptual model is proposed for the gas hydrate system of Pointer Ridge by detailed seismic attribute analysis. • Potential gas hydrate reservoirs that might be targets for future exploration are identified. Abstract Pointer Ridge is a gas hydrate prospect on the South China Sea continental slope offshore SW Taiwan. It is characterized by densely distributed bottom simulating reflections (BSRs), active gas seepage, and potential sandy gas hydrate reservoirs. To understand how the fluids have migrated toward the seafloor, and the role of geological processes in the gas hydrate system, we have collected and analyzed high-quality 2D and 3D reflection seismic data. We first mapped the spatial distribution of the BSRs, and interpreted a major normal fault, Pointer Ridge Fault (PR Fault). The NE-SW trending fault dips to the east, and separates the erosional regime to the west from the depositional regime to the east. One active vent site was identified directly above the PR Fault, while another is located on a topographic high to the west of the fault. On the hanging block of the fault we found at least one major unconformity. The seismic data indicate refilled channels with coarser-grained sediments in the hanging wall of the normal fault. Seismic attribute analysis shows subsurface fluid conduits and potential gas hydrate reservoirs. We propose two types of gas chimneys, which are separated by the fault. Gas plumes derived from hydroacoustic data are mostly from the footwall block of the fault. We infer that fluid flow is more active in the erosional environment compared to the depositional one, and that this is the result of reduced overburden. The methane-bearing fluids migrate upward along the PR Fault and chimneys and form hydrates above the base of the gas hydrate stability zone. Based on seismic interpretation and seismic attribute analysis, we postulate that the channel infill constitutes the most promising hydrate reservoirs in this geological setting. In the surveyed area of Pointer Ridge these channels occur mainly below the gas hydrate stability zone.
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  • 143
    Publication Date: 2019-05-06
    Description: Silicon (Si) isotopes are useful tracers for the modern and ancient Si cycle, but their interpretation is limited by inadequate understanding of Si isotope exchange kinetics and fractionation factors at low temperature. This study investigated Si isotope exchange and fractionation between aqueous and amorphous Si at circumneutral pH and room temperature through a series of 29Si-spiked isotope-exchange experiments. Four different amorphous Si solids with varied surface areas were reacted with aqueous Si solutions of high ionic strength similar to seawater, or low ionic strength typical of freshwater, under conditions close to chemical equilibrium with respect to amorphous Si solubility. In contrast to the common perception of negligible Si isotope exchange at low temperature, ∼50–85% isotope exchange was achieved between aqueous and amorphous Si within ∼60 days. Larger solid surface areas and higher aqueous ionic strength generally promoted Si isotope exchange. Drying/aging of Si gel, however, impedes Si isotope exchange between amorphous and aqueous Si relative to freshly prepared Si gels. Excluding the experiments that used the aged Si gel, temporal trajectories of Si isotope evolution of the two phases from all other experiments showed significant curvature in three-isotope space (29Si/28Si and 30Si/28Si). These results can be best explained by a model that comprises two Si isotope exchange processes with different exchange rates and fractionation factors during the interactions between aqueous and amorphous Si towards isotope equilibrium. The faster exchange is associated with surface sites, and slower exchange occurs between exterior and interior Si atoms of the solid. Exchange with surface sites tends to partition heavy Si isotopes in the aqueous phase relative to the solid surface, whereas exchange between surface and interior sites in the solid tends to enrich heavy Si isotopes in the interior. Two experiments that achieved 〉80% isotope exchange provided the best estimates of equilibrium Si isotope fractionation factors between bulk amorphous Si solid and aqueous monomeric silicic acid H4SiO4 (Δ30Siamorphous–aqueous) at 23 °C: +0.52‰ (±0.15‰, 1sd) at seawater ionic strength, and −0.98‰ (±0.12‰) at freshwater ionic strength. The observed “salt effect” on Si isotope exchange kinetics and fractionation factor is interpreted to reflect an influence of cations on Si speciation of solid surfaces. This work highlights the value of three-isotope method in studying both reaction kinetics and isotope fractionation mechanisms. The observed Si isotope exchange between amorphous and aqueous Si at low temperature implies that Si isotope re-equilibration, a previously neglected process, may be important in controlling Si isotope compositions of natural samples.
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  • 144
    Publication Date: 2019-05-06
    Description: The Pb isotope compositions of galena in hydrothermal deposits obtained by drillings from two hydrothermal fields in the middle Okinawa Trough were studied. One of the study fields was the Iheya North field located on a volcanic complex and the other was the Izena field located in the sediment-filled caldera structure. LA-MC-ICP-MS was applied to directly measure Pb isotope compositions in individual galena grains which highlighted variations not only in regional scale, but also in microscopic scale so that changes of Pb isotope compositions within a galena grain can be tracked. Homogeneous Pb isotope compositions were found within the same hydrothermal site, irrespective of the mineral assemblage, texture and sampling depth beneath the seafloor. In contrast, the isotope compositions varied significantly between the two hydrothermal fields. The Pb isotope composition from the Iheya North field was isotopically close to the volcanic rocks of the Okinawa Trough, whereas that from the Izena field was more radiogenic with values intermediate between sediments and volcanic rocks of the Okinawa Trough. Within the Iheya North field, intra-field variation of Pb isotope compositions was recognized between two active sites 2.5 km apart from each other. The intra-field variation was recognized also in the Izena field. The sub-seafloor massive sulfide layer has a more sediment-like Pb isotope composition, compared to the inactive sulfide mound. These results illustrate that the Pb-mineralizing hydrothermal fluids originate from their local host rocks with/without sediment and that the isotope compositions of the galena grains reflect their metal sources; either the volcanic rocks and/or the sediments via water-rock interactions.
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  • 145
    Publication Date: 2019-05-06
    Description: A simple and general relation between the solubility of quartz and the density of solution is derived rigorously. Based on this relation and the pressure-volume-temperature-composition model of Mao et al. (2010), an accurate density-based model is developed for the solubility of quartz in aqueous NaCl and/or CO2 solution up to 1273 K and 20,000 bar. The model parameters are regressed with carefully assessed experimental data. Compared to a large number of experimental data, the average absolute deviations of calculated quartz solubilities in water, aqueous NaCl solution and aqueous CO2 solution are 5.50%, 5.24% and 7.55%, respectively, which are within experimental uncertainties, and are much better than the most competitive models in literature. Particularly, this model can predict the experimental solubility of quartz in aqueous NaCl and CO2 solution without using any additional parameter. This model can be incorporated in software for accurate geochemical modeling. The strategy of this model should be promising for the solubilities of other minerals in water or multicomponent aqueous solutions.
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  • 146
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    Unknown
    In:  , 3 pp.
    Publication Date: 2019-05-07
    Description: 28. April - 4. Mai 2019
    Type: Report , NonPeerReviewed
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  • 147
    Publication Date: 2019-05-07
    Description: Emplacement of Large Igneous Provinces (LIPs) had a major effect on global climate, ocean chemistries as traced in sedimentary records and biotic turnovers. The linkage between LIPs and oceanic anoxic events has been documented with the Cenomanian/Turonian boundary event and Oceanic Anoxic Event 2 (OAE2). The Caribbean LIP and High Arctic Large Igneous Province (HALIP) are regarded as possible triggers. The pericratonic Arctic Sverdrup Basin is the partial location of the HALIP, where little is known about sedimentary, geochemical and biotic responses to the HALIP phases. Sedimentary strata at Glacier Fiord, Axel Heiberg Island, exhibit a dynamic Cretaceous polar carbon burial history within the lower to middle Cenomanian Bastion Ridge Formation and upper Cenomanian to Turonian part of the Kanguk Formation. We present the first initial 187Os/188Os (Osi) composition profile for a polar Cenomanian/Turonian boundary interval (∼100–93.9 Ma) linked to recently dated magmatic phases of the Strand Fiord Formation, part of the HALIP. The carbon isotope record coupled with the Osi profile show two events in the upper Cenomanian interval marked by positive carbon perturbations and shifts to more non-radiogenic Osi compositions. The earlier short-lived event is interpreted as result of weathering of the surrounding Strand Fiord volcanics causing a local non-radiogenic Osi signal. Coinciding transgressive shorelines let to an increase in marine and terrestrially derived organic matter. Subsequently, injection of mantle-derived basalts into organic rich sediments is credited with causing the release of methane documented in a distinct negative carbon isotope excursion. We speculate that the methane release of the HALIP was an important contribution for rapid global warming caused by increasing atmospheric CO2 levels associated with the OAE2 event likewise recognized in the Sverdrup Basin. As climate cooled in the middle and late Turonian, carbon burial decreased under increasingly oxygenated benthic conditions. Epifaunal foraminiferal species, adapted to low oxygen conditions, persisted during the OAE2. Our Cenomanian to Turonian multiproxy record of the Sverdrup Basin distinguishes between local and global signals within a restricted High Arctic basin. Our results demonstrate the interplay between basin tectonism and sea-level change, increased weathering during transgressive phases, seafloor processes such as hydrothermal activity and methane release and biotic response to a complex paleoceanography. With future reliable dated frameworks this unique polar record will facilitate correlations to other polar basins and records of lower paleolatitudes.
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  • 148
    Publication Date: 2019-05-07
    Description: Oceanic carbonate chemistry during the Cenozoic has affected the climatology, ecology, and marine geology of our planet; yet, we have limited means to know the evolution of that chemistry, due to a lack of preserved and unaltered seawater samples and a continuing paucity of proxies. Modeling is often used to address this problem; here, we offer a simple, data-driven, secular timescale, inverse model for the mean, Cenozoic, carbonate chemistry of the oceans. Inputs for the model include carbonate compensation depth (CCD), CaCO3 burial, seawater temperature, atmospheric CO2 and carbonate ion records, as well as a simple set of original, but justified, assumptions. The model retrodicts the total dissolved inorganic carbon (DIC), carbonate alkalinity (CAlk), and pH of the surface and deep waters of the ocean. The retrodicted DIC and CAlk records do not indicate any unusually elevated values in the early Cenozoic, as found in some past studies. If the CCD record from Lyle et al. (2008) is employed, the changes in DIC and CAlk appear entirely related to changes in the alkalinity input to the pelagic oceans and atmospheric CO2; however, with the CCD from Pälike et al. (2012), the increases in DIC and CAlk during the last 15 Ma reflect the effects of ocean cooling. Using either CCD-record, our model provides consistent retrodictions of the available pH record. Our results are not consistent with many past modeling assumptions, such as constancy of alkalinity in surface waters, or the ratio of shallow and deep carbonate ion concentrations. Finally, we use our results to provide new estimates of atmospheric CO2 based on Boron isotopes and find significantly lower CO2 values in the early Cenozoic than previous values.
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  • 149
    Publication Date: 2019-05-07
    Description: Sulfur (S) isotope compositions of pyrites in the sedimentary record have played an important part in our understanding of biogeochemical cycling in the geologic record. However, the kinetics of pyritization are complex and depend strongly on the reactivity and mineralogy of available iron. As a second major sink for sulfide in anoxic sediments, organic matter (OM) provides essential context for reconstructing the distribution and isotopic composition of environmental sulfide. To first order, roughly parallel pyrite and OM δ34S profiles reflect changes in sulfide, while independent patterns require alternative explanations, including changes in iron availability or OM characteristics. We apply this framework to Ocean Anoxic Event 2 (OAE-2, 94 Mya), a period of enhanced reduced C and S burial (in OM and pyrite) that was associated with expanded marine anoxia. We present paired S-isotope records for pyrite and OM along with profiles of OM S:C ratio and S redox speciation from four well-characterized lithologic sections (Pont d’Issole, Cismon, Tarfaya Basin, and Demerara Rise) to reconstruct both local redox structure and global mechanisms impacting the C, S and Fe cycles around OAE-2. OM sulfurization appears to be a major control on OM preservation at all four sites. Similar to modern anoxic environments, there is a positive correlation between OM S:C ratios and OM concentrations for sites with more reducing conditions, implying a link between OM sulfurization and burial. At consistently anoxic sites like Tarfaya Basin and Demerara Rise, strongly sulfurized OM with a consistent S redox speciation and S-isotope composition most likely formed rapidly in sinking particles before, during, and after OAE-2. Particle-hosted OM sulfurization may therefore have been a central mechanism facilitating the massive burial of OM in anoxic environments during this and other periods of enhanced global carbon burial. At the same time, a nearly 25‰ negative shift in the δ34S values of pyrite – but not OM – occurs at multiple, globally distributed sites near the onset of OAE-2, indicating slower pyritization reactions that likely reflect changes in iron delivery due to expanding regional or global anoxia. The combination of pyrite and organic S isotopes thus provides novel constraints on the interwoven cycles of carbon, iron, and sulfur across a major carbon cycle perturbation.
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  • 150
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    Society of Exploration Geophysicists
    In:  Geophysics, 84 (1). B75-B94.
    Publication Date: 2019-05-06
    Description: High-resolution 4D (HR4D) seismic data have the potential for improving the current state-of-the-art in detecting shallow (≤500−1000  m below seafloor) subsurface changes on a very fine scale (approximately 3–6 m). Time-lapse seismic investigations commonly use conventional broadband seismic data, considered low to moderate resolution in our context. We have developed the first comprehensive time -lapse analysis of high-resolution seismic data by assessing the repeatability of P-cable 3D seismic data (approximately 30–350 Hz) with short offsets and a high density of receivers. P-cable 3D seismic data sets have for decades been used to investigate shallow fluid flow and gas-hydrate systems. We analyze P-cable high-resolution 4D (HR4D) seismic data from three different geologic settings in the Arctic Circle. The first two are test sites with no evidence of shallow subsurface fluid flow, and the third is an active seepage site. Using these sites, we evaluate the reliability of the P-cable 3D seismic technology as a time-lapse tool and establish a 4D acquisition and processing workflow. Weather, waves, tide, and acquisition-parameters such as residual shot noise are factors affecting seismic repeatability. We achieve reasonable quantitative repeatability measures in stratified marine sediments at two test locations. However, repeatability is limited in areas that have poor penetration of seismic energy through the seafloor, such as glacial moraines or rough surface topography. The 4D anomalies in the active seepage site are spatially restricted to areas of focused fluid flow and might likely indicate changes in fluid flow. This approach can thus be applied to detect migration of fluids in active leakage structures, such as gas chimneys.
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  • 151
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    In:  , 2 pp.
    Publication Date: 2019-05-07
    Description: to Goldeneye, North Sea (1.05.-29.05.2019)
    Type: Report , NonPeerReviewed
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  • 152
    Publication Date: 2019-05-07
    Description: The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the unknown patterns of divergence and their impact on the ocean heat budget near the Equator, monitoring of the emerging Arctic up to 82.5$(\circ)$N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a state-of-the-art nadir beam comparable to the Poseidon-4 instrument on Sentinel 6. The well proven Doppler pulse-pair technique will give a surface drift velocity representative of the top two meters of the ocean, after subtracting a large wave-induced contribution. Horizontal velocity components will be obtained with an accuracy better than 7 cm/s for horizontal wavelengths larger than 80~km and time resolutions larger than 15 days, with a mean revisit time of 4 days for of 99\% of the global oceans. This will provide unique and innovative measurements that will further our understanding of the transports in the upper ocean layer, permanently distributing heat, carbon, plankton, and plastics. SKIM will also benefit from co-located measurements of water vapor, rain rate, sea ice concentration, and wind vectors provided by the European operational satellite MetOp-SG(B), allowing many joint analyses. SKIM is one of the two candidate satellite missions under development for ESA Earth Explorer 9. The other candidate is the Far infrared Radiation Understanding and Monitoring (FORUM). The final selection will be announced by September 2019, for a launch in the coming decade.
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  • 153
    Publication Date: 2019-03-13
    Description: In this study, an idealized eddy-resolving model is employed to examine the interplay between the downwelling, ocean convection and mesoscale eddies in the Labrador Sea and the spreading of dense water masses. The model output demonstrates a good agreement with observations with regard to the eddy field and convection characteristics. It also displays a basin mean net downwelling of 3.0 Sv. Our analysis confirms that the downwelling occurs near the west Greenland coast and that the eddies spawned from the boundary current play a major role in controlling the dynamics of the downwelling. The magnitude of the downwelling is positively correlated to the magnitude of the applied surface heat loss. However, we argue that this connection is indirect: the heat fluxes affect the convection properties as well as the eddy field, while the latter governs the Eulerian downwelling. With a passive tracer analysis we show that dense water is transported from the interior towards the boundary, predominantly towards the Labrador coast in shallow layers and towards the Greenland coast in deeper layers. The latter transport is steered by the presence of the eddy field. The outcome that the characteristics of the downwelling in a marginal sea like the Labrador Sea depend crucially on the properties of the eddy field emphasizes that it is essential to resolve the eddies to properly represent the downwelling and overturning in the North Atlantic Ocean, and its response to changing environmental conditions.
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  • 154
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    Academic Press
    In:  In: Ecological issues and environmental impacts. , ed. by Sheppard, C. World seas: an environmental evaluation, 3 . Academic Press, London, pp. 163-171. 2. ISBN 978-0-12-805052-1
    Publication Date: 2019-03-14
    Description: This chapter reviews the blooms of the moon jellyfish Aurelia, the most common jellyfish worldwide. Blooms of the moon jellyfish Aurelia have been reported in many coastal areas, including in Asia, Europe, Australia, and the United States. Multiple environmental factors, such as overfishing, coastal eutrophication, global warming, translocation, and habitat modification, are possible causes for blooms of the moon jellyfish Aurelia. The blooms of Aurelia spp. have negative impacts on the socioeconomics of coastal areas, that is, clogging the cooling intakes of coastal power plants and interfering with fisheries, aquaculture, and tourism. The eradication methods for controlling Aurelia spp. are also reviewed in this chapter.
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  • 155
    Publication Date: 2019-03-14
    Description: Transgenerational effects of multiple stressors on marine organisms are emerging environmental themes. We thus experimentally tested for transgenerational effects of seawater acidification and hypoxia on the early development traits of the mussel Mytilus edulis. Fertilization rate, embryo deformity rate, and larval shell length were negatively impacted by acidification, while hypoxia had little effect except for increasing deformity rates under control pH conditions. Offspring from low pH/O2 parents were less negatively affected by low pH/O2 conditions than offspring from control parents; however, low pH/O2 conditions still negatively affected developmental traits in offspring from acclimated parents compared to control seawater conditions. Our results demonstrate that experimental seawater acidification and hypoxia can adversely affect early developmental traits of M. edulis and that parental exposure can only partially alleviate these impacts. If experimental observations hold true in nature, it is unlikely that parental exposure will confer larval tolerance to ocean acidification for M. edulis.
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  • 156
    Publication Date: 2019-04-02
    Description: Highlights • Accounting for systematic bias is required for a realistic analytical uncertainty • Gas segmented flow techniques achieved a combined uncertainties of 1-4 % • Lab-on-Chip nitrate + nitrite analysers achieved a combined uncertainties 〈 5% Abstract Accurate and precise measurements of marine macronutrient concentrations are fundamental to our understanding of biogeochemical cycles in the ocean. Quantifying the measurement uncertainty associated with macronutrient measurements remains a challenge. Large systematic biases (up to 10 %) have been identified between datasets, restricting the ability of marine biogeochemists to distinguish between the effects of environmental processes and analytical uncertainty. In this study we combine the routine analyses of certified reference materials (CRMs) with the application of a simple statistical technique to quantify the combined (random + systematic) measurement uncertainty associated with marine macronutrient measurements using gas segmented flow techniques. We demonstrate that it is realistic to achieve combined uncertainties of ~1-4 % for nitrate + nitrite (ΣNOx), phosphate (PO43-) and silicic acid (Si(OH)4) measurements. This approach requires only the routine analyses of CRMs (i.e. it does not require inter-comparison exercises). As CRMs for marine macronutrients are now commercially available, it is advocated that this simple approach can improve the comparability of marine macronutrient datasets and therefore should be adopted as ‘best practice’. Novel autonomous Lab-on-Chip (LoC) technology is currently maturing to a point where it will soon become part of the marine chemist’s standard analytical toolkit used to determine marine macronutrient concentrations. Therefore, it is critical that a complete understanding of the measurement uncertainty of data produced by LoC analysers is achieved. In this study we analysed CRMs using 7 different LoC ΣNOx analysers to estimate a combined measurement uncertainty of 〈 5%. This demonstrates that with high quality manufacturing and laboratory practices, LoC analysers routinely produce high quality measurements of marine macronutrient concentrations.
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  • 157
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    In:  , 3 pp.
    Publication Date: 2019-03-11
    Description: 04.-11.03.2019
    Type: Report , NonPeerReviewed
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  • 158
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    In:  , 2 pp.
    Publication Date: 2019-03-11
    Description: Zweiter Wochenbericht der FS Poseidon Expedition POS 533 - AIMAC Atmosphäre-Ozean-Inseln-Biogeochemische Wechselwirkungen in den Makaronesischen Archipelen der Kap Verden, der Kanaren und Madeira (04.03.-10.03.2019) Mindelo (Kap Verden) - Las Palmas (Gran Canaria) - Funchal (Madeira) - Las Palmas
    Type: Report , NonPeerReviewed
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  • 159
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    AtlantOS
    In:  AtlantOS Deliverable, D2.7 . AtlantOS, 34 pp.
    Publication Date: 2019-03-13
    Description: Report on Tracers, Carbon and ADCPs: Report on transient tracer, carbonate system variables and ADCP data from hydrographic sections and a system to sustain these observations past AtlantOS on key hydrographic sections
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 160
    Publication Date: 2019-03-18
    Description: Rapid anthropogenic climate change is a major threat to ocean biodiversity, increasing the challenge for marine conservation. Strategic conservation planning, and more recently marine spatial planning (MSP) are among the most promising management tools to operationalize and enforce marine conservation. As yet, climate change is seldom incorporated into these plans, potentially curtailing the effectiveness of designated conservation areas under novel environmental conditions. Reliable assessment of current and future climate change threats requires the ability to map climate-driven eco-evolutionary changes and the identification of vulnerable and resistant populations. Here we explore the heretofore largely unrecognized value of information gained from physiological, ecological and evolutionary studies to MSP under ongoing climate change. For example, we explore how climate threats do not necessarily follow latitudinal gradients, such that both risk hotspots and refugia occur in mosaic distributions along species ranges - patterns that may be undetectable without knowledge of biological vulnerabilities at regional and local scales. Because co-occurring species can exhibit markedly different vulnerabilities to the same environmental changes, making ecological predictions requires, when possible, measuring the fundamental niches of key species (e.g., with the use of thermotolerance experiments). Forecasting also requires development of tools to identify the likelihood of community-level thresholds or tipping points (e.g., with the use of near-real world mesocosms), and assessment of the potential of populations for adaptation (e.g., with common garden experiments). Such research will facilitate better predictive models for the fate of populations, species, ecosystems and their functions. Ultimately, unfolding the complexity of the processes underlying climate change impacts will facilitate quantifying and reducing uncertainty in spatial planning decision processes and will enable the development of practical tools to validate adaptive conservation strategies.
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  • 161
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    GEOMAR
    In:  GEOMAR, Kiel, Germany, 11 pp.
    Publication Date: 2019-03-18
    Description: Dates of Cruise: 15.05. – 30.05.2018 Areas of Research: Physical, chemical, biological and fishery oceanography Port Calls: Riga. Latvia, 22.05.2018
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 162
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    AtlantOS
    In:  AtlantOS Deliverable, D10.12 . AtlantOS, 12 pp.
    Publication Date: 2019-03-18
    Description: Development and dissemination of up to 6 visual / interactive outputs aimed at stakeholder groups
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 163
    Publication Date: 2019-03-27
    Description: Highlights: • MPA is the most widely employed marine management tools. • Five potential habitats selected for MPA declaration in Bangladesh. • These habitats cover 7% of total maritime area of Bangladesh. • Local community involvement is required for a successful implementation of MPA. Abstract: Marine protected areas (MPAs) have become one of the most widely employed marine management tools worldwide for conserving species and habitats, maintaining ecosystem functioning, and ensuring sustainable use of marine resources. In this study, we adopted a science-based, stakeholder-driven and ecosystem based approach to identify coastal and marine habitats for potential MPA declaration towards achieving Aichi target 11. In addition, we also proposed an integrated management approach for MPA management in Bangladesh. Primary data were collected through stakeholder consultations from the three coastal zones of Bangladesh and secondary data were collected from an extensive literature review. We developed a priority index to select the most important habitats for MPA declaration. Our analysis suggests five potential habitats within the maritime boundary of Bangladesh for MPA declaration. These habitats cover an area of 8838 km2 which is about 7.5% of the total maritime area of Bangladesh. Declaration of the MPAs will contribute to conserve the nursing and breeding habitats of fishes, crabs and seabirds, and thus will protect the marine biodiversity. To achieve this goal, local community involvement is required. This study will serve as a baseline for declaring MPAs in a solid scientific way through community engagement.
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  • 164
    Publication Date: 2019-03-14
    Description: The individual impact of North Atlantic and Pacific Ocean Western Boundary Currents (OWBCs) on the tropospheric circulation has recently been studied in depth. However, their simultaneous role in shaping the hemisphere-scale wintertime troposphere/stratosphere-coupled circulation and its variability have not been considered. Through semi-idealized Atmospheric General-Circulation-Model experiments, we show that the North Atlantic and Pacific OWBCs jointly maintain and shape the wintertime hemispheric circulation and its leading mode of variability Northern Annular Mode (NAM). The OWBCs energize baroclinic waves that reinforce quasi-annular hemispheric structure in the tropospheric eddy-driven jetstreams and NAM variability. Without the OWBCs, the wintertime NAM variability is much weaker and its impact on the continental and maritime surface climate is largely insignificant. Atmospheric energy redistribution caused by the OWBCs acts to damp the near-surface atmospheric baroclinicity and compensates the associated oceanic meridional energy transport. Furthermore, the OWBCs substantially weaken the wintertime stratospheric polar vortex by enhancing the upward planetary wave propagation, and thereby affecting both stratospheric and tropospheric NAM-annularity. Whereas the overall impact of the extra-tropical OWBCs on the stratosphere results mainly from the Pacific, the impact on the troposphere results from both the Pacific and Atlantic OWBCs.
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  • 165
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    In:  , 4 pp.
    Publication Date: 2019-03-28
    Description: 18.-24.03.2019
    Type: Report , NonPeerReviewed
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  • 166
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    In:  , 3 pp.
    Publication Date: 2019-03-28
    Description: 11.-17.03.2019
    Type: Report , NonPeerReviewed
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  • 167
    Publication Date: 2019-03-28
    Description: We suggest a software pipeline for mixtures analysis. It combines tandem MS and 2D NMR data for a reliable identification of its constituents in an algorithm based on network analysis. An important part of this pipeline is the use of open-data repositories, although it is not totally reliant on them. The process starts with a LC-ESI-MSMS based molecular network dereplication using data from the GNPS collaborative collection. We identify closely related structures by propagating structure elucidation through edges in the network. Those identified compounds are added on top of a candidate list for the following NMR filtering method that predicts HSQC and HMBC NMR data. The similarity of the predicted spectra of the set of closely related structures to the measured spectra of the mixture sample is taken as one indication of the most likely candidates for its compounds. The other indication is the match of the spectra to clusters built by a network analysis from the spectra of the mixture. The contributions of the paper are an algorithm combining MS and NMR spectroscopy and a robust nJCH network analysis. This delivers good results even if a perfect computational separation of the compounds in the mixture is not possible. All the scripts will be made available online for users to aid studies such as with plants, marine organisms, and microorganism natural product chemistry and metabolomics as those are the driving force for this project.
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  • 168
    Publication Date: 2019-04-24
    Description: Volcanic island flank collapses have the potential to trigger devastating tsunamis threatening coastal communities and infrastructure. The 1888 sector collapse of Ritter Island, Papua New Guinea (in the following called Ritter) is the most voluminous volcanic island flank collapse in historic times. The associated tsunami had run-up heights of more than 20 m on the neighboring islands and reached settlements 600 km away from its source. This event provides an opportunity to advance our understanding of volcanic landslide-tsunami hazards. Here, we present a detailed reconstruction of the 1888 Ritter sector collapse based on high-resolution 2D and 3D seismic and bathymetric data covering the failed volcanic edifice and the associated mass-movement deposits. The 3D seismic data reveal that the catastrophic collapse of Ritter occurred in two phases: (1) Ritter was first affected by deep-seated, gradual spreading over a long time period, which is manifest in pronounced compressional deformation within the volcanic edifice and the adjacent seafloor sediments. A scoria cone at the foot of Ritter acted as a buttress, influencing the displacement and deformation of the western flank of the volcano and causing shearing within the volcanic edifice. (2) During the final, catastrophic phase of the collapse, about 2.4 km³ of Ritter disintegrated almost entirely and travelled as a highly energetic mass flow, which incised the underlying sediment. The irregular topography west of Ritter is a product of both compressional deformation and erosion. A crater-like depression underlying the recent volcanic cone and eyewitness accounts suggest that an explosion may have accompanied the catastrophic collapse. Our findings demonstrate that volcanic sector collapses may transform from slow gravitational deformation to catastrophic collapse. Understanding the processes involved in such a transformation is crucial for assessing the hazard potential of other volcanoes with slowly deforming flanks such as Mt. Etna or Kilauea.
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  • 169
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    Senckenberg am Meer
    In:  Senckenberg am Meer, Wilhelmshaven, Germany, 2 pp.
    Publication Date: 2019-04-04
    Description: (31.03. – 04.04.2019)
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  • 170
    Publication Date: 2019-04-08
    Description: Highlights • Systematic analysis of ship bathymetry enables segment scale geological mapping. • The Menez Gwen segment experiences magmatic periods every 300 to 500 ka. • Periods of enhanced magmatic activity are a regional phenomenon. • Hydrothermalism at Menez Gwen accompanies a waning, intense magmatic period. • Faulting and along-axis permeability variations focus hydrothermal venting. Abstract Slow-spreading mid-ocean ridges have the potential to form large seafloor massive sulphide (SMS) deposits. Current exploration for SMS deposits commonly targets associated active hydrothermal venting on the ridge axis, which makes the discovery of inactive vent sites and SMS deposits in the off-axis regions unlikely. Geological maps of the seafloor, which help understand the timing and location of SMS formation, usually focus on individual hydrothermal vent sites and their immediate surroundings, and are often too small to aid in SMS exploration. This study uses ship-based multibeam echosounder (MBES) data and a systematic classification scheme to produce a segment-scale geological map. When combined with spreading rate, this allows us to not only reconstruct the segment's spreading history, but also reveals important processes that localize hydrothermal venting. Geological mapping around two known hydrothermal vent sites on the Menez Gwen segment at 37°50′N on the slow-spreading Mid-Atlantic Ridge showed that hydrothermal venting accompanies the tectonic break-up of a large, cooling magmatic body. Venting is focussed by faulting and resulting permeability changes. The large magmatic body is associated with an axial volcano that formed as a last stage of a period with intense magmatic accretion. Such magmatic accretion periods occur every 300 to 500 ka at the Menez Gwen segment, with increasing intensity over the past 3.5 Ma years. The most recent, most intense magmatic period appears to be a regional phenomenon, also affecting the neighbouring Lucky Strike and Rifted Hills segments. Understanding the accretional setting and the spatial and temporal constraints of hydrothermal venting enables us to develop criteria in MBES data to aid exploration for inactive SMS deposits.
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  • 171
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    Senckenberg am Meer
    In:  Senckenberg am Meer, Wilhelmshaven, Germany, 5 pp.
    Publication Date: 2019-04-15
    Description: Cruise period: 20.3.2019 - 4.4.2019 Alkor cruise 520-2 was part of the project ASKAWZ (Acoustic Seafloor Classification of the German EEZ) funded by the Federal Maritime and Hydrographic Agency (BSH) and the Feral Agency for Nature Conservation (BfN). The main goal of the cruise was the full area acoustic mapping of the westernmost part of the German EEZ (so called “duck bill”) by sidescan sonar and the detection of natural and man-made structures (trawl marks) on the seafloor. The full area mapping was achieved by 61 sidescan sonar profiles, covering an area of ca. 640 km². A single-beam echosounder with automatic seafloor classification (QTC 5.5) was run simultaneously to the sidescan sonar. The acoustic backscatter data was “ground truthed” using Shipek grab and Box-corer (Reineck-Type) samples. In addition an underwater video camera was used to gather further seabed information. Aditionally sidescan data was recorded in the Helgoland-Reef pockmark area. Here 13 lines were surveyed (ca. 10 km²) by sidescan sonar in order to document the development of the pockmark field.
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  • 172
    Publication Date: 2019-04-11
    Description: We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become important are beginning to be resolved in regional and process models. Coupling to sea ice, ice shelves, and high-resolution atmospheric models has stimulated new ideas and driven improvements in numerics. Observations have provided insight into turbulence and mixing around the globe and its consequences are assessed through perturbed physics models. Relatedly, parameterizations of the mixing and overturning processes in boundary layers and the ocean interior have improved. New diagnostics being used for evaluating models alongside present and novel observations are briefly referenced. The overall goal is summarizing new developments in ocean modeling, including: how new and existing observations can be used, what modeling challenges remain, and how simulations can be used to support observations.
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  • 173
    Publication Date: 2019-04-30
    Type: Dataset
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  • 174
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    PANGAEA
    In:  Swiss Meteorological Agency, Payerne
    Publication Date: 2019-02-01
    Type: Dataset
    Format: text/tab-separated-values, 803308 data points
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