ALBERT

Beschreibung: The boundary between the American and European plates emerges in Iceland, an outstanding natural laboratory where it is possible to analyse ongoing rifting processes. In the North Volcanic Zone, we studied with unprecedented detail an active rift, known as the Theistareykir Fissure Swarm (ThFS). We surveyed an area of 85 km2 with 694 measurement sites along 1537 post-Late Glacial Maximum extension fractures. In the southern sector of the study area, fractures strike N30–40° with opening directions about N120°. Fractures in the central sector strike about N00° and opening directions are N90–100°. In the northern sector, fractures strike about N30° with opening directions about N125°. Through a comparison with older faults cropping out in the substrate at the shoulder of the ThFS, we are able to suggest that variations in fracture strike are the effect of substrate structural inheritance as well as the possible interaction with the Tjörnes Fracture Zone. With regard to kinematics, we highlight that most fractures show a small, but systematic, strike-slip component (a more frequent right-lateral component and a less common, left-lateral one). This cannot be explained as the result of fracture strike rotation relative to the regional, tectonic least principal stress. We conclude that the net opening directions can result from the combination of tectonic offsets and events caused by shallow magma chamber inflation and/or dyke intrusions. The latter can produce transcurrent components of displacement along new or already existing fractures.

Beschreibung: Highlights • Re-organization of the West Pacific Warm Pool at ~ 1.7 – 1.35 Ma. • West Pacific Warm Pool and South Pacific Convergence Zone located further to the NE prior to ~ 1.5 Ma. • High amplitude variations at thermocline and deep thermocline depths after ~ 1.5 Ma. • West Pacific Warm Pool thermocline dynamics linked to southern-sourced mode waters. Abstract The internal development of the tropical West Pacific Warm Pool and its interaction with high latitude ocean regions on geological timescales is only poorly constrained. Based on two newly recovered sediment cores from the southeastern margin of the West Pacific Warm Pool (northern and southern Manihiki Plateau), we provide new aspects on the dynamically interacting ocean circulation at surface, subsurface, thermocline, and deep thermocline levels during the Pleistocene (~ 2.5–0.5 Ma). Notably, the variability of thermocline and deep thermocline (~ 150–400 m water depth) foraminiferal Mg/Ca-based temperatures with up to ~ 6 °C amplitude variations exceeds those at shallower depths (down to ~ 120 m) with only ~ 2–3 °C temperature variations. A major gradual reorganization of the West Pacific Warm Pool oceanography occurred during the transitional time period of ~ 1.7–1.35 Ma. Prior to ~ 1.7 Ma, pronounced meridional and latitudinal gradients in sea-surface to subsurface ocean properties point to the eastward displacement of the West Pacific Warm Pool boundaries, with the South Pacific Convergence Zone being shifted further northeastward across Manihiki Plateau. Simultaneously, the low amplitude variations of thermocline and deep thermocline temperatures refer to an overall deep and stable thermocline. The meridional and zonal gradients in sea-surface and subsurface ocean properties within the West Pacific Warm Pool reveal a pronounced change after 1.5 Ma, leading to a more southward position of the warm South Pacific Convergence Zone between ~ 1.35–0.9 Ma and ~ 0.75–0.5 Ma. Synchronous to the changes in the upper ocean, the deeper water masses experienced high amplitude variations in temperature, most prominently since ~ 1.5 Ma. This and the dynamically changing thermocline were most likely associated to the impact of southern-sourced mode waters, which might have developed coincidently with the emergence of the East Pacific Cold Tongue and high latitude sea-surface cooling.

Beschreibung: Highlights • First apparent calcification depth assessment of living foraminifera in the SE WPWP • Deep surface mixed layer causes deep apparent calcification depths. • Deep-dwelling G. hexagonus traces nutrient conditions in equatorial water masses. Abstract Insight into past changes of upper ocean stratification, circulation, and nutrient signatures rely on our knowledge of the apparent calcification depth (ACD) and ecology of planktonic foraminifera, which serve as archives for paleoceanographic relevant geochemical signals. The ACD of different species varies strongly between ocean basins, but also regionally. We constrained foraminiferal ACDs in the Western Pacific Warm Pool (Manihiki Plateau) by comparing stable oxygen and carbon isotopes (δ18Ocalite, δ13Ccalcite) as well as Mg/Ca ratios from living planktonic foraminifera to in-situ physical and chemical water mass properties (temperature, salinity, δ18Oseawater, δ13CDIC). Our analyses point to Globigerinoides ruber as the shallowest dweller, followed by Globigerinoides sacculifer, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata and Globorotaloides hexagonus inhabiting increasing greater depths. These findings are consistent with other ocean basins; however, absolute ACDs differ from other studies. The uppermost mixed-layer species G. ruber and G. sacculifer denote mean calcification depths of ~ 95 m and ~ 120 m, respectively. These Western Pacific ACDs are much deeper than in most other studies and most likely relate to the thick surface mixed layer and the deep chlorophyll maximum in this region. Our results indicate that N. dutertrei appears to be influenced by mixing waters from the Pacific equatorial divergence, while P. obliquiloculata with an ACD of ~ 160 m is more suitable for thermocline reconstructions. ACDs of G. hexagonus reveal a deep calcification depth of ~ 450 m in oxygen-depleted, but nutrient-rich water masses, consistent to other studies. As the δ13C of G. hexagonus is in near-equilibrium with ambient seawater, we suggest this species is suitable for tracing nutrient conditions in equatorial water masses originating in extra-topical regions.

Beschreibung: High-latitude cold-water coral reefs are particularly vulnerable to climate change due to enhanced CO2 uptake in these regions. To evaluate their physiological functioning and potential application as pH archives, we retrieved both recent and fossil samples of Lophelia pertusa along the Norwegian margin from Oslofjord (59°N), over to Trondheimsfjord, Sula and Lopphavet (70.6°N). Boron isotope analyses (δ11B) were undertaken using solution-based and laser ablation multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS; LA-ICP-MS), and secondary ion mass spectrometry (SIMS). Epi-fluorescence microscopy was employed to provide a rapid pre-screening routine for structure-specific subsampling in the coral skeleton. This integrated approach enabled us to assess heterogeneities within single specimens, as well as to investigate the role of local environmental influences including recent and past variations. All three mass spectrometry methods show substantial differences in the δ11B of the theca wall (TW) and the centres of calcification (COC's). Micro-bulk subsamples milled from the theca wall of modern specimens originating from different habitats but with comparable seawater pH (8–8.16) gave consistent δ11B values averaging 26.7 (±0.2‰, 2σ, n = 4), while COC subsamples systematically deviated towards lower B/Ca (by ~40%) and depleted δ11B values (minimum 22.7 ± 0.3‰, 2σ), implying a difference of at least 4‰ between TW and COC. SIMS and LA-ICP-MS measurements identified much larger internal heterogeneities with maximum variation of ~10‰ between the distinct skeletal structures; minimal SIMS δ11B values of ~17.3 ± 1.2‰ (2σ) were associated with the pure COC material. Our findings may be interpreted in terms of the occurrence of two main, but likely different, biomineralisation mechanisms in L. pertusa, with the COC's generally exhibiting minimal pH up-regulation, potentially supporting the use of bicarbonate in the early stages of biomineralisation. Furthermore, we highlight the potential utility of L. pertusa for palaeo-proxy studies if targeting the compositionally homogenous TW zones devoid of COC admixtures, which appear to provide highly reproducible measurements.

Beschreibung: A mesocosm experiment with intact benthic communities was conducted to evaluate the effects of mine tailings on benthic community structure and biogeochemical processes. Two types of tailings were supplied from process plants using flotation and flocculation chemicals, while a third type was absent of added chemicals. All tailings impacted the sediment community at thin layers, and through more mechanisms than merely hypersedimentation. In general, the strongest impact was observed in a very fine-grained tailings containing flotation chemicals. The second strongest occurred in tailings with no process chemicals. The tailings with flocculation chemicals initiated the weakest response. Fluxes of oxygen, nitrate and ammonium provided some indications on biodegradation of organic phases. Release of phosphate and silicate decreased with increasing layer thickness of all three tailings. A threshold level of 2 cm was identified both for faunal responses and for fluxes of phosphate and silicate. The particular impact mechanisms should receive more attention in future studies in order to minimize the environmental risk associated with tailings disposal.

Beschreibung: Increasingly more data have indicated that the 40Ar/39Ar crushing technique provides a very useful approach to determine the mineralization ages of hydrothermal ore deposits. In this study novel gas mixing lines are proposed based on the data of two quartz samples by 40Ar/39Ar crushing. Electron microprobe analyses indicate that the quartz grains contain K-rich silicate microlites. Both quartzs by crushing yield two mixing lines with ages corresponding respectively to those of K-feldspar or sericite (post-mineralization fluids) and muscovite samples (ore-forming fluids). This is the first report that both ages of secondary and primary fluid inclusions (SFIs and PFIs) are confirmed correspondingly by those of the K-rich minerals. This study strongly indicates that the 40Ar/39Ar crushing technique is very useful to determine the ages of geofluid activities. The newly proposed gas mixing patterns are shown on the inverse and normal isochron diagrams, indicating: (1) the mixtures are in different proportions of the PFIs and SFIs in different crushing steps; (2) the gas mixing lines yield PFI ages with low initial 40Ar/36Ar ratios; (3) an intermediate age between PFI and SFI ages cannot be obtained because the progressive crushing technique never release gas mixtures with a constant PFI/SFI proportion for each step. The gas mixing lines are thus interpreted to yield significant geological ages. The mixing patterns will help us better understand the 40Ar/39Ar dating results and be used for references to other isotopic mixing isochron systems.

Beschreibung: A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic stream draining an abandoned copper mine in north Wales. The isolate (PY-F3) was demonstrated to be a heterotroph that catalyzed the oxidation of ferrous iron (but not of sulfur or hydrogen) under aerobic conditions, and the reduction of ferric iron under micro-aerobic and anaerobic conditions. PY-F3 formed long entangled filaments of cells (〉50 μm long) during active growth phases, though these degenerated into smaller fragments and single cells in late stationary phase. Although isolate PY-F3 was not observed to grow below pH 2.0 and 10 °C, harvested biomass was found to oxidize ferrous iron at relatively fast rates at pH 1.5 and 5 °C. Phylogenetic analysis, based on comparisons of 16S rRNA gene sequences, showed that isolate PY-F3 has 91–93% gene similarity to those of the four classified genera and species of acidophilic Actinobacteria, and therefore is a representative of a novel genus. The binomial Acidithrix ferrooxidans is proposed for this new species, with PY-F3 as the designated type strain (=DSM 28176T, =JCM 19728T).

Beschreibung: Stable isotopes (15,14N, 18,16O) of dissolved inorganic nitrogen (N) were measured in sediment porewaters and benthic flux chambers across the Peruvian oxygen minimum zone (OMZ) from 74 to 1000 m water depth. Sediments at all locations were net consumers of bottom water NO3−. In waters shallower than 400 m, this sink was largely attributed to dissimilatory nitrate reduction to ammonium (DNRA) by filamentous nitrate-storing bacteria (Marithioploca and Beggiatoa) and to denitrification by foraminifera. The apparent N isotope effect of benthic NO3− loss (15εapp) was 7.4 ± 0.7‰ at microbial mat sites and 2.5 ± 0.9‰ at the lower fringe of the OMZ (400 m) where foraminifera were abundant. The OMZ sediments were a source of 15N-enriched NO2− (28.9 to 65.5‰) and NH4+ (19.4–20.5‰) to the bottom water. Model simulations generally support a previous hypothesis attributing the 15NH4+ enrichment to a coupling between DNRA and anammox (termed DAX) using biologically-stored NO3− from Marithioploca and NH4+ from the porewater. The model predicts that 40% of NO3− that is actively transported into the sediment by Marithioploca is reduced to N2 by this pathway. DAX enhances N2 fluxes by a factor of 2–3 and accounts for 70% of fixed N loss to N2. Moreover, because most of the ambient porewater NH4+ is generated by DNRA, up to two-thirds of biologically-transported NO3− could end up being lost to N2. This challenges the premise that Marithioploca-dominated sediments tend to conserve fixed N. By limiting the flux of 15NH4+ back to the ocean, DAX also tends to decrease benthic N fractionation. Tracking the fate of NH4+ once it leaves the sediment is critical for understanding how the benthos contributes to N isotope signals in the water column.

Beschreibung: Editorial

Beschreibung: Transient tracer data (CFC-12 and SF6) from three oceanographic field campaigns to the Mauritanian Upwelling area conducted during winter, spring and summer from 2005 to 2007 is presented. The transient tracers are used to constrain a possible solution to the transient time distribution (TTD) along 18°N and to quantify the mean ages in vertical sections perpendicular to the coast. We found that an Inverse Gaussian distribution where the ratio of the moments δ and Γ equals 1.2 is a possible solution (δ/Γ=1.2) of the TTD. The transient tracers further show considerable under-saturation in the mixed layer during the winter and spring cruises that can only be maintained by mixing or upwelling by tracer-poor water from below the mixed layer. We use dissipation data from microstructure measurements and the tracer depth distribution to quantify the flux of tracers to the mixed layer by vertical diffusivity and wind data from the ship to quantify the air-sea flux. We then use the magnitude of the under-saturation in the mixed layer to estimate the advective upwelling velocity which is the balance the first two processes, in a steady state assumption. We find that the upwelling velocities range from less than 1 to 5.6×10-5ms-1 (〈0.8-4.8md-1), with generally higher values close to the coast, but with comparable upwelling velocities during spring and winter. During the summer cruise the transient tracers were close to equilibrium with the atmosphere, suggesting no upwelling. We have shown the use of CFC-12 and SF6 transient tracer data for calculating upwelling velocity, and found an overall uncertainty of roughly ±50%.

Beschreibung: In this chapter the role of the ocean on climate and climate change is discussed in terms of the properties of oceans and in terms of the tools available to oceanographers. The details of the Atlantic Meridional Overturning Circulation (AMOC) are described with special reference to motivation, driving mechanisms, heat transport and the ocean's uptake of carbon and the ventilation of the deep ocean. The past changes of the AMOC and the Atlantic climate are also discussed. The chapter ends with a discussion of three questions: • Why should the AMOC change as a result of climate change? • Can we detect changes in the AMOC? • Is the AMOC already changing as a result of climate change?

Beschreibung: Diapycnal diffusivity estimates from two Tracer Release Experiments (TREs) and microstructure measurements in the oxycline and core of the oxygen minimum zone (OMZ) in the eastern tropical North Atlantic are compared. For the first time, two TREs within the same area at different depths were realized: the Guinea Upwelling Tracer Release Experiment (GUTRE) initiated in 2008 in the oxycline at approximately 320 m depth, and the Oxygen Supply Tracer Release Experiment (OSTRE) initiated in 2012 in the core of the OMZ at approximately 410 m depth. The mean diapycnal diffusivity Dz was found to be insignificantly smaller in the OMZ core with (1.06 ± 0.24) × 10− 5 m2 s− 1 compared to (1.11 ± 0.22) × 10− 5 m2 s− 1 90 m shallower in the oxycline. Unexpectedly, GUTRE tracer was detected during two of the OSTRE surveys which showed that the estimated diapycnal diffusivity from GUTRE over a time period of seven years was within the uncertainty of the previous estimates over a time period of three years. The results are consistent with the Dz estimates from microstructure measurements and demonstrate that Dz does not vary significantly vertically in the OMZ within the depth range of 200–600 m and does not change with time. The presence of a seamount chain in the vicinity of the GUTRE injection region did not cause enhanced Dz compared to the smoother bottom topography of the OSTRE injection region, although the analysis of vertical shear spectra from ship ADCP data showed elevated internal wave energy level in the seamount vicinity. However, the two tracer patches covered increasingly overlapping areas with time and thus spatially integrated increasingly similar fields of local diffusivity, as well as the difference in local stratification counteracted the influence of roughness on Dz. For both experiments no significant vertical displacements of the tracer were observed, thus diapycnal upwelling within the ETNA OMZ is below the uncertainty level of 5 m yr− 1.

Beschreibung: Highlights • “Black Smokers” on slow-spreading ridges can host larger seafloor massive sulfide (SMS) deposits than on fast ridges. • The largest slow-ridge SMS deposits are typically associated with long-lived tectonic fractures ± sustained fluid flow. • Ultramafic-, tectonic-hosted sites exhibit high average Cu (〉 10wt.%) and Au (〉 3ppm) contents in their surface SMS samples. • Hydrothermal plume surveys are consistent with equal abundances of magmatic vs tectonic vent-control along ultraslow ridges. • The first “Black Smokers” on any ultraslow ridges exhibit high Cu ± Au SMS contents at both magmatic and tectonic vent-sites. Abstract Here, we review the relationship between the distribution of modern-day seafloor hydrothermal activity along the global mid-ocean ridge crest and the nature of the mineral deposits being formed at those sites. Since the first discovery of seafloor venting, a sustained body of exploration has now prospected for one form of hydrothermal activity in particular – high temperature “black smoker” venting – along 〉 30% of the global mid-ocean ridge crest. While that still leaves most of that ~ 60,000 km continuous network to be explored, some important trends have already emerged. First, it is now known that submarine venting can occur along all mid-ocean ridges, regardless of spreading rate, and in all ocean basins. Further, to a first approximation, the abundance of currently active venting, as deduced from water column plume signals, can be scaled linearly with seafloor spreading rate (a simple proxy for magmatic heat-flux). What can also be recognized, however, is that there is an “excess” of high temperature venting along slow and ultra-slow spreading ridges when compared to what was originally predicted from seafloor spreading/magmatic heat-budget models. An examination of hydrothermal systems tracked to source on the slow spreading Mid-Atlantic Ridge reveals that no more than half of the sites responsible for the “black smoker” plume signals observed in the overlying water column are associated with magmatic systems comparable to those known from fast-spreading ridges. The other half of all currently known active high-temperature submarine systems on the Mid-Atlantic Ridge are hosted under tectonic control. These systems appear both to be longer-lived than, and to give rise to much larger sulfide deposits than, their magmatic counterparts — presumably as a result of sustained fluid flow. A majority of these tectonic-hosted systems also involve water–rock interaction with ultramafic sources. Importantly, from a mineral resource perspective, this subset of tectonic-hosted vent-sites also represents the only actively-forming seafloor massive sulfide deposits on mid-ocean ridges that exhibit high concentrations of Cu and Au in their surface samples (〉 10 wt.% average Cu content and 〉 3 ppm average Au). Along ultraslow-spreading ridges, first detailed examinations of hydrothermally active sites suggest that sulfide deposit formation at those sites may depart even further from the spreading-rate model than slow-spreading ridges do. Hydrothermal plume distributions along ultraslow ridges follow the same (~ 50:50) distribution of “black smoker” plume signals between magmatic and tectonic settings as the slow spreading MAR. However, the first three “black smoker” sites tracked to source on any ultra-slow ridges have all revealed high temperature vent-sites that host large polymetallic sulfide deposits in both magmatic as well as tectonic settings. Further, deposits in both types of setting have now been revealed to exhibit moderate to high concentrations of Cu and Au, respectively. An important implication is that ultra-slow ridges may represent the strongest mineral resource potential for the global ridge crest, despite being host to the lowest magmatic heat budget.

Beschreibung: We present high-resolution records of sedimentary nitrogen (δ15Nbulk) and carbon isotope ratios (δ13Cbulk) from piston core SO201-2-85KL located in the western Bering Sea. The records reflect changes in surface nitrate utilization and terrestrial organic matter contribution in submillennial resolution that span the last 180 kyr. The δ15Nbulk record is characterized by a minimum during the penultimate interglacial indicating low nitrate utilization (~62–80%) despite the relatively high export production inferred from opal concentrations along with a significant reduction in the terrestrial organic matter fraction (mterr). This suggests that the consumption of the nitrate pool at our site was incomplete and even more reduced than today (~84%). δ15Nbulk increases from Marine Isotope Stage (MIS) 5.4 and culminates during the Last Glacial Maximum, which indicates that nitrate utilization in the Bering Sea was raised during cold intervals (MIS 5.4, 5.2, 4) and almost complete during MIS 3 and 2 (~93–100%). This is in agreement with previous hypotheses suggesting that stronger glacial stratification reduced the nutrient supply from the subeuphotic zone, thereby increasing the iron-to-nutrient ratio and therefore the nitrate utilization in the mixed surface layer. Large variations in δ15Nbulk were also recorded from 180 to 130 ka BP (MIS 6), indicating a potential link to insolation and sea-level forcing and its related feedbacks. Millennial-scale oscillations were observed in δ15Nbulk and δ13Cbulk that might be related to Greenland interstadials.

Beschreibung: Nitric oxide (NO) is a short-lived compound of the marine nitrogen cycle. However, measurements of NO in seawater are analytically challenging and our knowledge about its oceanic distribution is, therefore, rudimentary. NO was measured in the oxygen minimum zone (OMZ) of the eastern tropical South Pacific Ocean (ETSP) off Peru during R/V Meteor cruise M93 in February/March 2013. NO concentrations ranged from close to or below the detection limit (0.5nmolL-1) in the surface layer to 9.5nmolL-1 in the OMZ. NO concentrations increased significantly when oxygen (O2) concentrations dropped below 1-2μmolL-1. We found positive correlations between NO and NO2 - as well as between NO and the abundance of archaeal amoA, a marker gene for archaeal nitrifiers. No trends between NO and nirS and hzo, marker genes for canonical denitrification and anammox, respectively, were found. To this end, we conclude that NO off Peru was mainly produced by archaeal nitrifier-denitrification at low O2 concentrations in the OMZ.

Beschreibung: The vertical distributions of early developmental stages of oceanic fishes were investigated across the tropical and equatorial Atlantic, from oligotrophic waters close to the Brazilian coast to more productive waters close to the Mauritanian Upwelling Region. Stratification of the water column was observed throughout the study region. Fishes were caught with a MOCNESS-1 net with mouth area of 1 m2 at 11 stations. Each station was sampled both during the day and at night within a single 24-h period. The investigation covered both larvae and transforming stages from the surface to 800 m depth. Distribution patterns were analysed, and weighted mean depths for the larvae and transforming stages of each species were calculated for day and night conditions. Forty-seven different species were found. The highest number of species occurred in the three stations south of Cape Verde Islands, characterized by a mixture of South Atlantic Central Water (SACW) and Eastern North Atlantic Central Water (ENACW). There was a marked drop in species richness in the three stations closer to the African upwelling, dominated by ENACW. The highest abundances occurred in the families Myctophidae, Sternoptychidae, Gonostomatidae and Phosichthyidae. Day and night vertical distributions of larvae and transforming stages showed contrasting patterns, both in the depths of the main concentration layers in the water column, and in the diel migration patterns (where these were observed). Larvae generally showed a preference for the upper mixed layer (ca. 0–50 m) and upper thermocline (ca. 50–100 m), except for sternoptychids, which were also abundant in the lower thermocline layer (100–200 m) and even extended into the mesopelagic zone (down to 500 m). Transforming stages showed a more widespread distribution, with main concentrations in the mesopelagic zone (200–800 m). Larvae showed peak concentrations in the more illuminated and zooplankton-rich upper mixed layers during the day and a wider distribution through the upper 100 m during the night. For most species, transforming stages were concentrated in the mesopelagic layers both day and night, although in some species (Diaphus cf. vanhoeffeni and Vinciguerria nimbaria), the transforming stages displayed vertical migration into the upper 100 m at night, in a manner similar to their adult stages.

Beschreibung: We present the application of a micro/macro parareal algorithm for a 1-D energy balance climate model with discontinuous and non-monotone coefficients and forcing terms. The micro/macro parareal method uses a coarse propagator, based on a (macroscopic) 0-D approximation of the underlying (microscopic) 1-D model. We compare the performance of the method using different versions of the macro model, as well as different numerical schemes for the micro propagator, namely an explicit Euler method with constant stepsize and an adaptive library routine. We study convergence of the method and the theoretical gain in computational time in a realization on parallel processors. We show that, in this example and for all settings, the micro/macro parareal method converges in fewer iterations than the number of used parareal subintervals, and that a theoretical gain in performance of up to 10 is possible.

Beschreibung: The timing of past glaciation across the Tian Shan provides a proxy for past climate change in this critical area. Correlating glacial stages across the region is difficult but cosmogenic exposure ages have considerable potential. A drawback is the large observed scatter in 10Be surface exposure data. To quantify the robustness of the dating, we compile, recalculate, and perform statistical analyses on sets of 10Be surface exposure ages from 25 moraines, consisting of 114 new and previously published ages. We assess boulder age scatter by dividing boulder groups into quality classes and rejecting boulder groups of poor quality. This allows us to distinguish and correlate robustly dated glacier limits, resulting in a more conservative chronology than advanced in previous publications. Our analysis shows that only one regional glacial stage can be reliably correlated across the Tian Shan, with glacier expansions occurring between 15 and 28 ka during marine oxygen isotope stage (MIS) 2. However, there are examples of older more extensive indicators of glacial stages between MIS 3 and MIS 6. Paleoglacier extent during MIS 2 was mainly restricted to valley glaciation. Local deviations occur: in the central Kyrgyz Tian Shan paleoglaciers were more extensive and we propose that the topographic context explains this pattern. Correlation between glacial stages prior to late MIS 2 is less reliable, because of the low number of samples and/or the poor resolution of the dating. With the current resolution and spatial coverage of robustly-dated glacier limits we advise that paleoclimatic implications for the Tian Shan glacial chronology beyond MIS 2 are speculative and that continued work toward robust glacial chronologies is needed to resolve questions regarding drivers of past glaciation in the Tian Shan and Central Asia.

Beschreibung: Major shifts in ocean circulation are thought to be responsible for abrupt changes in temperature and atmospheric CO2 during the last deglaciation, linked to variability in meridional heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2 rise, including enhanced diatom production in regions such as the tropical Atlantic. However, it remains unclear as to whether this diatom production was driven by enhanced wind-driven upwelling or density-driven vertical mixing, or by elevated thermocline concentrations of silicic acid supplied to the surface at a constant rate. Here, we demonstrate that silicic acid supply at depth in the NE Atlantic was enhanced during the abrupt climate events of the deglaciation. We use marine sediment archives to show that an increase in diatom production during abrupt climate shifts could only occur in regions of the NE Atlantic where the deep supply of silicic acid could reach the surface. The associated changes are indicative of enhanced regional wind-driven upwelling and/or weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced thermocline concentrations of silicic acid suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling.

Beschreibung: A recent optimality-based model for phytoplankton growth and diazotrophy was applied at two stations located in the oligotrophic western and the ultra-oligotrophic eastern subtropical North Atlantic. Contrary to the common view that diazotrophy is favoured by nitrogen (N) depletion relative to the Redfield equivalent of phosphorus (P), we find that optimality-based diazotrophy could explain N fixation in both regions in spite of relatively high N:P supply ratios. This is possible because the availability of an additional source of N for diazotrophs makes them strong competitors for P under oligotrophic conditions. The best reproduction of observations, especially of net primary production, is only achieved with preferential remineralization of P relative to N and atmospheric deposition. In line with observations, a higher rate of nitrogen fixation is predicted for the eastern site, owing to a larger niche for diazotrophs resulting from stronger oligotrophy and lower N:P supply ratios due to weaker atmospheric N deposition. Because the competitive advantage of diazotrophs under nutrient starvation diminishes with increasing supply N:P ratio, the predicted increase of atmospheric N deposition due to anthropogenic activity could negatively affect N2 fixation in the Atlantic Ocean.

Beschreibung: Dissolved silicon isotope compositions (δ30Si) have been analysed for the first time in groundwaters of beach sediments, which represent a subterranean estuary with fresh groundwater discharge from a freshwater reservoir and mixing with recirculated seawater. The fresh groundwater reservoir has high and variable dissolved silica concentrations between 136 and 736 μM, but homogeneous δ30Si of +1.0 ± 0.15‰. By contrast, the seawater is strongly depleted in dissolved silica with concentrations of 3 μM, and consequently characterised by high δ30Si of +3.0‰. The beach groundwaters are variably enriched in dissolved silica compared to seawater (23–192 μM), and concentrations increase with depth at all sampling sites. The corresponding δ30Si values are highly variable (+0.3‰ to +2.2‰) and decrease with depth at each site. All groundwater δ30Si values are lower than seawater and most values are lower than dissolved δ30Si of freshwater discharge indicating a significant amount of lithogenic silica dissolution in beach sediments. In contrast to open North Sea sediments, diatom dissolution or formation of authigenic silica in beach sediments is very low (ca. 5 μmol Si g−1). Silica discharge from the beach to the coastal ocean is estimated as approximately 210 mol Si yr−1 per meter shoreline. Considering the extent of coastline this is, at least for the study area, a significant amount of the total Si budget and amounts to ca. 1% of river and 3.5% of backbarrier tidal flat area Si input.

Beschreibung: Isocitrate dehydrogenase (IDH) is one of the key enzymes in the tricarboxylic acid cycle, and IDH mutations have been associated with many cancers, including glioblastoma, sarcoma, acute myeloid leukemia, etc. Three natural steroids 1–3 from Ganoderma sinense, a unique and rare edible-medicinal fungi in China, were found as potential IDH1 inhibitors by virtual ligand screening method. Among the three compounds, 3 showed the highest binding affinity to IDH1 with significant calculated binding free energy. Enzymatic kinetics demonstrated that 3 inhibited mutant enzyme in a noncompetitive manner. The half effective concentration of 3 for reducing the concentration of D-2HG in HT1080 cells was 35.97 μM. The levels of histone H3K9me3 methylation in HT1080 cells were reduced by treating with 3. Furthermore, knockdown of mutant IDH1 in HT1080 cells decreased the anti-proliferative sensitivity to 3. In short, our findings highlight that compound 3 may have clinical potential in tumor therapies as an effective inhibitor of mutant IDH1.

Beschreibung: Environmental DNA (eDNA) degradation is a primary mechanism limiting the detection of rare species using eDNA techniques. To better understand the environmental drivers of eDNA degradation, we conducted a laboratory experiment to quantify degradation rates. We held bullfrog (Lithobates catesbeianus) tadpoles in microcosms, then removed the tadpoles and assigned the microcosms to three levels each of temperature, ultraviolet B (UV-B) radiation, and pH in a full factorial design. We collected water samples from each microcosm at six time steps (0 to 58 days). In all microcosms, most degradation occurred in the first three to 10 days of the experiment, but eDNA remained detectable after 58 days in some treatments. Degradation rates were lowest under cold temperatures (5 °C), low UV-B levels, and alkaline conditions. Higher degradation rates were associated with factors that contribute to favorable environments for microbial growth (higher temperatures, neutral pH, moderately high UV-B), indicating that the effects of these factors may be biologically mediated. The results of this experiment indicate that aquatic habitats that are colder, more protected from solar radiation, and more alkaline are likely to hold detectable amounts of eDNA longer than those that are warmer, sunnier, and neutral or acidic. These results can be used to facilitate better characterization of environmental conditions that reduce eDNA persistence, improved design of temporal sampling intervals and inference, and more robust detection of aquatic species with eDNA methods.

Beschreibung: Quantifying the pathways of fixed nitrogen (N) loss in marine oxygen deficient zones (ODZs) and the isotopic fractionation caused by these processes are important for understanding the marine fixed N budget and its potential for change. In this study, a variety of approaches were used to quantify fixed N loss in the eastern tropical South Pacific Ocean (ETSP). The required measurements included nutrient concentration (nitrate—NO3-, nitrite—NO2-, and phosphate—PO43-), gas ratio (N2/Ar) measurements, and stable N and O isotopes in NO3-, NO2-, and nitrogen gas (N2). The dissolved inorganic nitrogen deficit calculated from [PO43-] ([DIN]def,P) exceeded the concentration of N2 gas biologically produced in the ODZ (local [N2]bio) throughout the ODZ at most stations, likely due to release of PO43- from sediments driving up [DIN]def,P. Calculating DIN deficit using water mass analysis and local oxygen (O2) consumption ([DIN]def,OMP) yielded better agreement with local [N2]bio than [DIN]def,P, except at the maximum [N2]bio, where [DIN]def,OMP misses contributions of anaerobic ammonia oxidation (anammox) to N2 production. We used the mismatch between [DIN]def,OMP and [N2]bio to estimate a 29% contribution of anammox to [N2]bio. Stable isotopic measurements of NO2-, NO3-, and N2 were used alongside [N2]bio and new estimates of [DIN]def to calculate N and O isotope effects for NO3- reduction (15εNAR and 18εNAR, respectively), and N isotope effects for DIN removal (15εDIN-R). While the various methods for estimating [DIN]def had little effect on the isotope effects for DIN removal, differences between 15εNAR and 15εDIN-R, and variations with depth in the ODZ were observed. Using a simple time-dependent ODZ model, we interpreted these patterns to reflect the influences of NO2- oxidation and NO2- accumulation on expression of isotopic fractionation in the ODZ.

Beschreibung: The Yap subduction zone in the western Pacific presents some unique features compared to normal intra-oceanic subduction zones such as the subduction of an oceanic plateau. However, due to the relative paucity of geophysical data, the detailed structure remains unknown in this area. In this study, we present the latest high-quality swath bathymetry and multi-channel seismic data acquired synchronously in 2015 across the Yap subduction zone. The topographic and sedimentary features are intensively investigated and a modified evolutionary model of the Yap subduction zone is proposed. The two-stage evolution of the Parece Vela Basin (PVB) produced fabrics that are N-S trending and NW-SE trending. Our seismic data clearly reveal landslide deposits at the upper slope break of the forearc, to the north of the Yap Island, which was identified as the fault notch denoting a lithological boundary in previous work. The swath bathymetry and seismic profile reveal detailed horst and graben structures, including a crescent-shaped fault zone near the contact between the Yap Trench and the Caroline Ridge. A simple geometric model is proposed to explain the structure formation, indicating that the higher topography of the Caroline Ridge resulted in enhanced bending-related extension. A seismic angular unconformity (named R1) is identified in the Sorol Trough, marking the onset of rifting in the trough. Based on the sequence thickness and deposition rate by Deep Sea Drilling Project (DSDP), it is deduced that the Sorol Trough formed at 10 Ma or even earlier. A modified model for the Yap subduction zone evolution is proposed, incorporating three major tectonic events: the proto-Yap Arc rupture in the Oligocene, the collision of the Caroline Ridge and the Yap Trench in the late Oligocene or middle Miocene, and the onset of the Sorol Trough rifting in the late Miocene.

Beschreibung: Highlights • Methionine synthesis in M. jannaschii delivers a novel target for strain engineering. • Analysis of DsrAB reveals so far unknown, uncultured bacterial genera. • Elucidation of the role of DsrC links sulfite reduction to energy conservation. • Sulfate reducing microbes can be used to improve wastewater treatment. Sulfur, the least common of the five macroelements, plays an important role in biochemistry due to its ability to be easily reduced or oxidized, leading to a great amount of research concerning sulfur bioconversion. Interestingly, new studies concerning microbial sulfate reduction pathways in the last half decade have become increasingly sparse, indicating that most of the pathways involved have been discovered and studied. Despite this, systems biology approaches to model these pathways are often missing or not used. As the products of microbial sulfate reduction play important roles in the environment, biotechnology, and industry, modeling sulfur bioconversion remains an untapped research space for future work.

Beschreibung: Since its inception in the mid-1960s, the 40Ar/39Ar dating technique has been the premier method for determining the eruption ages of basaltic rocks, providing valuable insights into a plethora of terrestrial and planetary processes. Advances in multi-collector mass spectrometry and improved sample preparation procedures are enabling ever-improving analytical precision and clearer evaluation of the isotopic disturbances that affect many basaltic samples and cause discordant 40Ar/39Ar age spectra. Here, we present 40Ar/39Ar step-heating data for multiple samples from two Quaternary basalt flows (0.8038 ± 0.0017 and 2.309 ± 0.009 Ma) of the intraplate Newer Volcanic Province, southeast Australia. A small proportion of these samples give concordant 40Ar/39Ar results, but most are variably discordant. The factors controlling these disturbances and implications for accurate age determination are examined and modelled in both step-heating spectra and inverse isochron space. We demonstrate that the proportion of radiogenic 40Ar (40Ar⁎) present in these samples strongly influences the nature of the discordance reflected in 40Ar/39Ar data. Mass-dependent fractionation appears to have a major influence on low-40Ar⁎ samples, whereas 39Ar recoil loss/redistribution effects are evident in samples with higher 40Ar⁎ proportions. The impact of mass fractionation is quantified via step-heating analyses of unirradiated basalt, whereby a ∼4% difference in 38Ar/36Ar ratios is observed between low- and high-temperature heating steps. On an inverse isochron plot (39Ar/40Ar vs 36Ar/40Ar), isotopic disturbance for groundmass samples primarily manifests as isochron rotation, leading to a negative correlation between initial 40Ar/36Ar ([40Ar/36Ar]i) values and associated 40Ar/39Ar ages. We propose a new framework for the interpretation of 40Ar/39Ar step-heating data for basaltic samples, through judicious evaluation of inverse isochron data, (40Ar/36Ar)i ratios and inverse isochron ages. Results from this study suggest that only samples exhibiting both flat 40Ar/39Ar age spectra and atmospheric (40Ar/36Ar)i ratios yield accurate eruption ages; in the case of more discordant age spectra, intermediate temperature steps with atmospheric (40Ar/36Ar)i ratios may provide the closest approximation of the eruption age.

Beschreibung: Clay-rich salt marshes of mesotidal Wadden Sea coasts and of estuaries have been established mainly within artificial sedimentation fields in front of embankments. Natural salt marsh formation and natural range expansion outside artificial structures were rare. In the last three decades of this century natural marshes along the southern Wadden Sea coast of Schleswig-Holstein, Germany, started to grow outside groyne fields and extended on tidal mudflats. This growth happened without direct human influence and naturally structured marshes of considerable spatial dimension evolved. Due to a spread in recent decades, natural grown marshes in our study area – southern Schleswig-Holstein Wadden Sea coast - are younger than man-made marshes. Vegetation developed rapidly in response to fine-scaled geomorphological conditions. Meandering creeks and different surface elevation ranges of the developing natural salt marsh are special features. The naturally grown marshes show a high proportion of pioneer vegetation with Spartina anglica and Salicornia europaea. Succession proceeds fast and elevated parts of the marsh were rapidly colonised with marsh vegetation of Puccinellia maritima and Aster tripolium in the lower marsh to late successional stages, like Halimione portulacoides and Elymus athericus, on the higher elevated parts. Strikingly, median elevations of the vegetation zones in the natural marsh were several centimetres lower than those of the man-made marsh. The largest difference between both marsh types was the characteristic and the extent of drainage systems. Naturally grown marshes have a natural developed, fine-branched and four times shorter drainage system than man-made marshes with a dense drainage structure.

Beschreibung: The orogenic history of the Tibetan Plateau (TP) and surrounding mountain ranges continues to be a major source of disagreement among geologists, particularly concerning the uplift models for the Cenozoic evolution of the TP and estimates for when the highest and largest plateau on Earth reached its current elevation. Quantitative reconstructions of past elevation from geologic samples are necessary to document the uplift history of TP and examine the interactions between tectonic-relief and climate over geological time-scales. Several studies establishing lipid biomarker-based paleoaltimetry based on leaf wax δD values and brGDGTs have been reported in recent years for the TP and surrounding regions, but have yet to be synthesized into a regional framework for paleoelevation determination and uncertainty analysis. Here we report new leaf wax δD and brGDGTs data developed from surface soil samples along an elevation transect spanning ~1250–3900 m.a.s.l in the Hengduan Mountains on the southeastern edge of the TP. We find that the abundance-weighted mean leaf wax δD (n-C27, n-C29 and n-C31) values (δDwax) lapse rates determined for the Hengduan Mountains and for five other nearby study locations are statistically indistinguishable, and can be combined to provide a regional δDwax lapse rate of −1.97 ± 0.04‰ (1σ)/100 m for use in regional paleoelevation studies across the southeastern TP. We also find a strong correlation (R2 = 0.71) between brGDGTs and elevation-dependent mean annual air temperature, which contributes to a number of studies in the region that support the use of fossil brGDGTs as a paleoelevation proxy. Our results reveal that δDwax and brGDGTs for the Hengduan Mountains provide similar empirical uncertainty in paleoelevation reconstruction, with standard errors of elevation estimation (SE) of ±483 m (±1σ) and ± 394 m (±1σ), respectively. We propose a paleoaltimetric approach that combines δDwax and brGDGT data, in order to derive paleoelevation estimates with lower uncertainties. In the Hengduan Mountains data set, the approach yields a SE (±286 m; ±1σ) that is 27–40% lower than when δDwax values and brGDGTs are applied separately.

Beschreibung: The ability of species to recover from disturbance through natural recruitment is an important factor in determining the resilience of assemblages. The identification of patterns of resilience compatible or favoured by human activities has become a compelling need to address environmental management. In marine coastal systems, barrens are characterized by a dominance of encrusting calcareous algae and by high density of sea urchins and are considered an alternative stable state of systems collapsed due to overgrazing by sea urchins that originally were dominated by canopy-forming macroalga. Sea urchins also represent an important commercial resource, as some species are exploited worldwide. The present study aims at evaluating the effect of the harvesting of the sea urchin Paracentrotus lividus on promoting the shift from barren towards macroalgal beds. Three treatments were considered within a manipulative experiment in a Cystoseira-barren mixed habitat: natural sea urchins density, removal of all sea urchins and removal of only commercial P. lividus (natural density of the non-harvested sea urchin Arbacia lixula and juvenile P. lividus are maintained). Results showed that the removal of commercial P. lividus can promote Cystoseira recruitment. In fact, even if both A. lixula and juvenile P. lividus were present, the barren area decreased due to the spread of fleshy algae and the recruitment of the Cystoseira from the edge of vegetated patches. Therefore, removal of commercial P. lividus urchin is inferred as a reliable strategy to return ecosystems dominated by canopy-forming macroalgae.

Beschreibung: Data analysis represents a key challenge for untargeted metabolomics studies and it commonly requires extensive processing of more than thousands of metabolite peaks included in raw high-resolution MS data. Although a number of software packages have been developed to facilitate untargeted data processing, they have not been comprehensively scrutinized in the capability of feature detection, quantification and marker selection using a well-defined benchmark sample set. In this study, we acquired a benchmark dataset from standard mixtures consisting of 1100 compounds with specified concentration ratios including 130 compounds with significant variation of concentrations. Five software evaluated here (MS-Dial, MZmine 2, XCMS, MarkerView, and Compound Discoverer) showed similar performance in detection of true features derived from compounds in the mixtures. However, significant differences between untargeted metabolomics software were observed in relative quantification of true features in the benchmark dataset. MZmine 2 outperformed the other software in terms of quantification accuracy and it reported the most true discriminating markers together with the fewest false markers. Furthermore, we assessed selection of discriminating markers by different software using both the benchmark dataset and a real-case metabolomics dataset to propose combined usage of two software for increasing confidence of biomarker identification. Our findings from comprehensive evaluation of untargeted metabolomics software would help guide future improvements of these widely used bioinformatics tools and enable users to properly interpret their metabolomics results.

Beschreibung: Human-induced global change is expected to amplify the disease risk for marine biota. However, the role of disease in the rapid global decline of seagrass is largely unknown. Global change may enhance seagrass susceptibility to disease through enhanced physiological stress, while simultaneously promoting pathogen development. This review outlines the characteristics of disease-forming organisms and potential impacts of global change on three groups of known seagrass pathogens: labyrinthulids, oomycetes and Phytomyxea. We propose that hypersalinity, climate warming and eutrophication pose the greatest risk for increasing frequency of disease outbreaks in seagrasses by increasing seagrass stress and lowering seagrass resilience. In some instances, global change may also promote pathogen development. However, there is currently a paucity of information on these seagrass pathosystems. We emphasise the need to expand current research to better understand the seagrass-pathogen relationships, serving to inform predicative modelling and management of seagrass disease under future global change scenarios.

Beschreibung: Upper layer diapycnal mixing in the Subtropical Front (STF) was estimated using microstructure shear profiles collected from the Indian sector of the Southern Ocean (ISSO) during the austral summer of 2012. Observations were made in the northern and southern boundary of the highly mesoscale turbulent STF, which is characterized by the presence of the dynamic Agulhas Return Current. During the observational period, the STF was populated with alternating cyclonic and anticyclonic eddies. In this mesoscale turbulent region, the average eddy diffusivity at the base of the euphotic zone was 5.5 × 10−5 m2 s−1. The average diapycnal nitrogen flux at the base of the euphotic zone, calculated using direct turbulence measurements, and nitrate (NO3) and nitrite (NO2) concentrations, was 6.4 × 10−5 μ mol m−2 s−1. The satellite-derived primary production in the STF was ~1000 mg C m−2 day−1. The observed diapycnal nutrient flux could only sustain 〈1% of the production observed in the region. Analysis of satellite-derived ocean currents, sea level anomalies, and thermohaline distribution further shows that despite the study area is a highly mesoscale turbulent region, the primary supply of nutrients is a result of advection (vertical or zonal) rather than vertical mixing.

Beschreibung: Highlights • First fission track and (U-Th-Sm)/He data from eastern Marie Byrd Land • First direct dating of Cenozoic WARS activity outside the Ross Sea area • Structural model kinematically linking areas of extended crust within the WARS • Data on paleotopographic evolution providing boundary conditions for glaciation Abstract The West Antarctic Rift System is one of the largest continental rifts on Earth. Because it is obscured by the West Antarctic Ice Sheet, its evolution is still poorly understood. Here we present the first low-temperature thermochronology data from eastern Marie Byrd Land, an area that stretches ~ 1000 km along the rift system, in order to shed light on its development. Furthermore, we petrographically analysed glacially transported detritus deposited in the marine realm, offshore Marie Byrd Land, to augment the data available from the limited terrestrial exposures. Our data provide information about the subglacial geology, and the tectonic and morphologic history of the rift system. Dominant lithologies of coastal Marie Byrd Land are igneous rocks that intruded (presumably early Paleozoic) low-grade meta-sedimentary rocks. No evidence was found for un-metamorphosed sedimentary rocks exposed beneath the ice. According to the thermochronology data, rifting occurred in two episodes. The earlier occurred between ~ 100 and 60 Ma and led to widespread tectonic denudation and block faulting over large areas of Marie Byrd Land. The later episode started during the Early Oligocene and was confined to western Pine Island Bay area. This Oligocene tectonic activity may be linked kinematically to previously described rift structures reaching into Bellingshausen Sea and beneath Pine Island Glacier, all assumed to be of Cenozoic age. However, our data provide the first direct evidence for Cenozoic tectonic activity along the rift system outside the Ross Sea area. Furthermore, we tentatively suggest that uplift of the Marie Byrd Land dome only started at ~ 20 Ma; that is, nearly 10 Ma later than previously assumed. The Marie Byrd Land dome is the only extensive part of continental West Antarctica elevated above sea level. Since the formation of a continental ice sheet requires a significant area of emergent land, our data, although only based on few samples, imply that extensive glaciation of this part of West Antarctica may have only started since the early Miocene.

Beschreibung: In recent years, mitochondrial nitric oxide (NO) production has attracted increasing attention. Mitochondria generate NO using nitrite as a substrate. Cytochrome c oxidase and other components of the electron transport chain also contribute to NO generation. Accumulating evidence indicates that mitochondria are scavengers of NO. Furthermore, several genes encoding mitochondrial proteins, as well as mitochondrial proteins, are regulated by NO. In this chapter, we provided an overview of the mechanisms of NO generation and scavenging in mitochondria and of the NO-dependent regulation of proteins and genes encoding mitochondrial proteins. In addition, the functional roles of NO in mitochondrial metabolism, such as inhibition of aconitase, production of ATP and induction of alternative oxidase are presented.

Beschreibung: A sulfated polysaccharide was successfully isolated from Cymodocea nodosa (CNSP). This is the first report that indicates the chemical composition, structural characterization, functional and antihypertensive properties of this polysaccharide. The CNSP consisted mainly of sulfate (23.17%), total sugars (54.90%), galactose (44.89%), mannose (17.30%), arabinose (12.05%), xylose (9.18%), maltose (1.07%) and uronic acid (11.03%) with low water activity (0.49). CNSP had an XRD pattern that was typical for a semi-crystalline polymer with homogeneous structure. It also displayed an important anti-hypertensive activity (IC50 = 0.43 mg ml) with a dose-dependent manner using a synthetic substrate, N-hippuryl-His-Leu hydrate salt (HHL). Overall, the results indicate that CNSP have attractive chemical, functional and biological properties, with a preliminary structural may have a backbone of branched 6-O-sulfated (1 → 4) galactosidic linkages, which can be considered in the future as alternative additive in various foods, cosmetic and pharmaceutical preparations.

Beschreibung: The anthropogenic trace gases chlorofluorocarbon (CFC)-12 and sulfur hexafluoride (SF6) were measured during 2013 in the eastern tropical South Pacific Ocean (ETSP) offshore Chile and Peru (12°-22°S, 70°-86°W). Since the WOCE P21 line along ~17°S in 1993, the CFC-12 penetration depth increased from ~550 m to ~800 m. In 2013, CFC-12 had penetrated through the bottom of the oxygen deficient zone (ODZ, where oxygen (O2) 〈 4.5 μmol kg−1) at all stations, indicating that a portion of waters in this ODZ are ventilated on timescales 〈 60 years. Isopycnal trends in pSF6 and pCFC-12 ages versus AOU indicated oxygen utilization rates of 11.2 ± 4.7 μmol kg−1 yr−1 just above the ODZ (90–130 m) and 1.0 ± 0.5 μmol kg−1 yr−1 beneath the ODZ (400–700 m). Isopycnal trends in pSF6 ages and nutrients implied fixed N-loss rates of 0.6 ± 0.4 μmol kg−1 yr−1 at the top of the ODZ (~120 m). The pSF6 and pCFC-12 ages were significantly younger than mean ages estimated from one-dimensional transit time distributions, which were difficult to constrain using the SF6 and CFC-12 tracer combination. Despite the fact that tracer concentrations tend to underestimate mean ages, and thus overestimate nutrient regeneration/consumption rates, N-loss rates were undetectable (〈0.5 μmol kg−1 yr−1) within the ODZ itself (~175–400 m). When integrated over depth, the oxygen and nitrogen consumption rates determined above and below the ODZ implied total organic carbon (C) remineralization rates on the order of 0.6 ± 0.1 mol C m−2 yr−1. These low C-export rates, and the decadal ventilation timescale of this ODZ, support a body of work suggesting that the ODZ may be sustained by inputs of high-tracer, low-oxygen waters from the adjacent Peru-Chile coastal upwelling system rather than by organic matter oxidation occurring locally.

Beschreibung: Copper-containing amine oxidases (CuAOs) have a broad range of functions, including respond to abiotic stresses, formation and differentiation of adipocytes in mammals. To verify the correlation between lipid accumulation and CuAOs in microalgae, the full-length gene of one copper amine oxidase isoform 2 from Chlorella sp. HN11 (ChlCAO2) was cloned, and the gene expression and enzymatic activity were determined. Then the correlation between lipid accumulation and CuAOs activities was further examined in C. vulgaris C3 and Chlamydomonas reinhardtii CC425. The results showed that the cDNA of ChlCAO2 was 4135 bp in length with a 2454 bp open reading frame (ORF). No lipid accumulation and up-regulated ChlCAO2 expression were observed in cells cultured in normal medium (the control) within 96 h. The relative fluorescence intensity of lipids in Chlorella cells under N-starvation was 3.03, 4.48, 4.17, and 4.63 times higher than the control at 24 h, 48 h, 72 h, and 96 h, respectively. While the expression of ChlCAO2 significantly increased by 105, 397, 808, and 333 times higher than the control at 24 h, 48 h, 72 h, and 96 h, respectively, the activity of ChlCAOs of N-starved increased correspondingly. When cells under N-starvation were resupplied with N at 48 h (N-recovery), lipid accumulation, the expression of ChlCAO2 and the activity of ChlCAOs decreased significantly (P 〈 0.05) at 72 h and 96 h compared with N-starvation. Correlation analysis showed that the relative fluorescence intensity of lipid, the expression of ChlCAO2, and the activity of ChlCAOs in Chlorella were markedly positively correlated with each other. Positive correlation between lipid accumulation and CuAO activities were both observed in C. vulgaris C3 and C.reinhardtii CC425.The results indicated that CuAOs play a key role in the process of lipid accumulation induced by nitrogen starvation in green algae.

Beschreibung: Highlights • Pronounced northeastern Greenland Ice Sheet retreat during early MIS5e. • Downstream effect of Greenland-derived meltwater. • Climatic decoupling between the Nordic Seas, the North Atlantic and the Labrador Sea. • Meltwater event during late MIS5e. Abstract Proximal evidence of the surface ocean response to size reduction of the Greenland Ice Sheet (GIS) during the Last Interglacial (MIS5e) and preceding glacial termination (T2) remains largely elusive. Using a new sediment record from the western Iceland Sea, the behavior of the northeastern GIS and its relation to the subpolar North Atlantic surface hydrography is examined. Extremely light oxygen isotopic (δ18O) values are found off central East Greenland during early MIS5e and point to enhanced meltwater release, potentially from the northeastern sector of the GIS. Data from downstream the cold East Greenland Current (EGC) and its eastward branches suggest a far-reaching effect of this meltwater not only in the Nordic Seas but also in the SE Labrador Sea. In particular, whereas an early MIS5e warming (at ∼128.5–126.5 ka) in the two regions coincided with the relative reduction of meltwater input into the EGC, the subsequent cooling noted at ∼126.5 ka followed a renewed major freshwater event off central East Greenland. Our data further indicate persistent freshwater influence from the East Greenland margin over the entire MIS5e interval and, in addition, also reveal a late MIS5e meltwater event. The latter event occurred just prior to the last glacial inception and emphasizes the importance of Greenland meltwater as forcing factor on Interglacial climates.

Beschreibung: The upper crust of central Europe preserves a mosaic of tectonic blocks brought together by the Caledonian and Variscan Orogenies. The lower crust, in contrast, appears to have undergone extensive reworking: the flat Moho across broad areas and the absence of contrasts in seismic properties across tectonic boundaries suggest that the Moho and lower crust are, effectively, younger than the upper crust. The evolution of the mantle lithosphere below the Moho has been particularly difficult to constrain. In this paper, we use seismic, geological and geochemical evidence to show that central Europe's mantle lithosphere has evolved continuously throughout the Mesozoic and Cenozoic Eras, with episodes of lithospheric thinning causing surface uplift and volcanism and lithospheric thickening - subsidence and sedimentation. High-resolution surface wave tomography reveals a strong spatial correlation between locations of recent basaltic volcanism and currently thin lithosphere. We infer that intraplate volcanism further back in the geological past is also an indication of lithospheric thinning at the time. The north-central Europe's lithosphere was, thus, thinned at the time of the Permian volcanism, with its subsequent, Post-Permian cooling and thickening causing the subsidence and sedimentation in the North German and neighboring basins. This explains the presence of Permian volcanics atop presently thickened lithosphere. South of these basins, lithospheric thinning (evidenced by seismic data) is associated with the volcanism of the Central European Cenozoic Igneous Province and surface uplift. Thin lithosphere here also correlates spatially with high melting rates, high silica contents, high temperatures and shallow magma generation. This synthesis highlights the dynamic nature of the lithosphere-asthenosphere boundary beneath central Europe and, more generally, Phanerozoic continents. The boundary's depth varies in time; its deepening (lithospheric cooling and thickening) causes subsidence and sedimentation; its shallowing (lithospheric thinning by thermal erosion or delamination) is marked with uplift and intraplate volcanism.

Beschreibung: Highlights • Surface Mg/Ca-temperatures and salinities show comparable glacial conditions. • Subsurface Mg/Ca-temperatures suggest that LGM is ∼3 to ∼2 °C colder than MIS 6. • Relative to Holocene, subsurface salinities suggest fresher LGM and saltier MIS 6 • Thermal gradients suggest stratified LGM and well-mixed MIS 6 water column. • Contrasting glacial scenarios suggest variable formation and advection of SOIWs. Abstract The Intermediate Waters formed in the Southern Ocean are critical for ventilating the thermocline in the Southern Hemisphere Gyres and transporting climatic signals from high to low latitudes on glacial-interglacial time-scales. Despite the importance of the Southern Ocean Intermediate Waters (SOIWs), information on past changes in SOIWs formation is fragmentary, and its impact on the South Pacific Gyre (SPG)'s thermocline largely unknown. Here, we present a 200 kyr record of paired Mg/Ca ratios and stable oxygen isotope from surface and deep dwelling planktonic foraminifera, from the SPG. On average, the Globigerina bulloides Mg/Ca-derived sea surface temperatures show similar conditions during the LGM and Marine Isotope Stage (MIS) 6 (9.4 °C versus 9.8 °C). In contrast, the subsurface temperatures derived from the Mg/Ca values of Globorotalia inflata and Globorotalia truncatulinoides suggest that LGM is ∼3 to ∼2  °C colder than MIS 6. Furthermore, at subsurface depths the reconstructed δ18Osw-ivc record (proxy for relative local salinity changes) suggests opposite glacial conditions, with slightly saltier-than-Holocene waters during MIS 6, and fresher-than-Holocene waters during LGM. Contrasting glacial scenarios, plausibly due to changes in the presence of SOIWs at the study site, suggest variable formation and/or advection of SOIWs to the SPG during different glacial stages. The variability in SOIWs is probably driven by the changes in the intensity of the Southern Westerly Winds.

Beschreibung: Trace element partition coefficients between anorthitic plagioclase and basaltic melts (D) have been determined experimentally at 0.6 GPa and 1350–1400 °C in a lunar high-Ti picritic glass and a mid-ocean ridge basalt (MORB). Plagioclases with 98 mol% and 86 mol% anorthite were produced in the lunar picritic melt and MORB melt, respectively. Based on the new experimental partitioning data and those selected from the literature, we developed parameterized lattice strain models for the partitioning of monovalent (Na, K, Li), divalent (Ca, Mg, Ba, Sr, Ra) and trivalent (REE and Y) cations between plagioclase and silicate melt. Through the new models we showed that the partitioning of these trace elements in plagioclase depends on temperature, pressure, and the abundances of Ca and Na in plagioclase. Particularly, Na content in plagioclase primarily controls divalent element partitioning, while temperature and Ca content in plagioclase are the dominant factors for REE partitioning in plagioclase. From these models, we also derived a new expression for DRa/DBa that can be used for Ra-Th dating on volcanic plagioclase phenocrysts, and a new model for plagioclase-melt noble gas partitioning. Applications of these partitioning models to fractional crystallization of MORB and lunar magma ocean (LMO) indicate that (1) the competing effect of temperature and plagioclase composition leads to small variations of plagioclase-melt DREE during MORB differentiation, but (2) the temperature effect is especially significant and can vary anorthite-melt DREE by over one order of magnitude during LMO solidification. Temperature and plagioclase composition have to be considered when modeling the chemical differentiation of mafic to felsic magmas involving plagioclase.

Beschreibung: Segonzacia mesatlantica inhabits different hydrothermal vent sites of the Mid-Atlantic Ridge where it experiences chronic environmental hypoxia, and highly variable temperatures. Experimental animals in aquaria at in situ pressure were exposed to varying oxygen concentrations and temperature, and their cardiac response was studied. S. mesatlantica is well adapted to these challenging conditions and capable of regulating its oxygen uptake down to very low concentrations (7.3–14.2 µmol l−1). In S. mesatlantica, this capacity most likely relies on an increased ventilation rate, while the heart rate remains stable down to this critical oxygen tension. When not exposed to temperature increase, hypoxia corresponds to metabolic hypoxia and the response likely only involves ventilation modulation, as in shallow-water relatives. For S. mesatlantica however, an environmental temperature increase is usually correlated with more pronounced hypoxia. Although the response to hypoxia is similar at 10 and 20 °C, temperature itself has a strong effect on the heart rate and EKG signal amplitude. As in shallow water species, the heart rate increases with temperature. Our study revealed that the range of thermal tolerance for S. mesatlantica ranges from 6 through 21 °C for specimens from the shallow site Menez Gwen (800 m), and from 3 through 19 °C for specimens from the deeper sites explored (2700–3000 m).

Beschreibung: The dissolution rates of olivine have been considered by a plethora of studies in part due to its potential to aid in carbon storage and the ease in obtaining pure samples for laboratory experiments. Due to the relative simplicity of its dissolution mechanism, most of these studies provide mutually consistent results such that a comparison of their rates can provide insight into the reactivity of silicate minerals as a whole. Olivine dissolution is controlled by the breaking of octahedral M2+-oxygen bonds at or near the surface, liberating adjoining SiO44− tetrahedra to the aqueous fluid. Aqueous species that adsorb to these bonds apparently accelerate their destruction. For example, the absorption of H+, H2O and, at some conditions, selected aqueous organic species will increase olivine dissolution rates. Nevertheless, other factors can slow olivine dissolution rates. Notably, olivine dissolution rates are slowed by lowering the surface area exposed to the reactive aqueous fluid, by for example the presence and/or growth on these surfaces of either microbes or secondary phases. The degree to which secondary phases decelerate rates depends on their ability to limit access of the reactive aqueous fluids to the olivine surface. It seems likely that these surface area limiting processes are very significant in natural systems, lowering olivine surface reactivity in many environments compared to rates measured on cleaned surfaces in the laboratory. A survey of the literature suggests that the major factors influencing forsteritic olivine dissolution rates are 1) pH, 2) water activity, 3) temperature, and 4) mineral-fluid interfacial surface area. Evidence suggests that the effects of aqueous inorganic and organic species are relatively limited, and may be attributed at least in part to their influence on aqueous solution pH. Moreover, the observed decrease in rates due to the presence of secondary mineral coatings and/or the presence of microbes can be attributed to their ability to decrease olivine surface area directly exposed to the reactive aqueous fluid. As the reactivity of forsterite surfaces are spatially heterogeneous, its surface area normalized rates will tend to decrease as it dissolves even in the absence of a mineral or bacterial coating. Each of these factors limits and or influences the application of forsterite dissolution to 1) enhanced weathering efforts, 2) mineral carbonation, and 3) the low temperature generation of hydrogen or hydrocarbons via the oxidation of its divalent iron.

Beschreibung: Cyanobacteria are oxygenic phoautotrophs that can utilize inorganic nitrogen salts, atmospheric nitrogen and some amino acids such as arginine as nitrogen source. Under unbalanced growth in the presence of sufficient nitrogen, many cyanobacteria accumulate cyanophycin, a co-polymer of aspartate and arginine that serves as a nitrogen reservoir. Cyanophycin metabolism enzymes include cyanophycin synthetases, cyanophycinase and isoaspartyl dipeptidase. The latter splits β‑aspartyl arginine released from cyanophycin by cyanophycinase into aspartate and arginine. The arginine catabolic pathway of cyanobacteria has been recently elucidated and consists of two bifunctional enzymes, arginine-guanidine removing enzyme (AgrE) and proline oxidase (PutA). This pathway makes available to metabolism the four nitrogen atoms of arginine, three as ammonia and one as glutamate. A variant of the pathway cycles ornithine (an intermediate in the AgrE-catalyzed reactions) back to arginine incorporating aspartate and, hence, recovering its nitrogen atom for metabolism. Many cyanobacteria also make use of this pathway to utilize arginine taken up from the outer medium through a high-affinity ABC transporter. An analysis of co-occurrence in cyanobacteria of genes encoding cyanophycin metabolism and arginine catabolism enzymes and arginine and aspartate transporters indicates a strong correlation between the presence of cyanophycin and the AgrE/PutA pathway.

Beschreibung: There is a recognized need for new methods with modest data requirements to provide preliminary estimates of stock status for data-limited stocks (e.g. Rudd and Thorson, 2018). Froese et al. (2018) provide such a method, which derives estimates of relative stock size from length frequency (LF) data of exploited stocks. They show that their length-based Bayesian biomass estimation method (LBB) can reproduce the “true” parameters used in simulated data and can approximate the relative stock size as estimated independently by more data-demanding methods in 34 real stocks. However, in a comment on LBB, Hordyk et al. (2019) claim (i) that the master equation of LBB is incomplete because it does not correct for the pile-up effect caused by aggregating length measurements into length classes or “bins”, (ii) that LBB is highly sensitive to equilibrium assumptions and wrongly uses maximum observed length (Lmax) for guidance in setting a prior for the estimation of asymptotic length (Linf), and (iii) that the default prior used by LBB for the ratio between natural mortality and somatic growth rate (M/K) of 1.5 (SD = 0.15) is inadequate for many exploited species. These comments are addressed below

Beschreibung: Mineral-dust aerosols from deserts are ubiquitous in the atmosphere. Despite their small size, desert-dust aerosols play multiple important roles in the Earth system. These include effects on the radiation budget, hydrological and biogeochemical cycles, land and ocean ecosystems, as well as human health. This reference module gives a broad introduction to the topic. The text describes major sources, properties, and impacts of desert-dust aerosols.

Beschreibung: Highlights: • North African dust emission and emission frequency from six models are examined. • There is a power law relationship between emission and emission event frequency. • The lognormal distribution of surface winds gives rise to this power law relation. • Annual North Africa dust emission is estimated via satellite retrievals of emission frequency. • We estimate that 82% of all North Africa dust emission is between 15° and 20°N. Abstract: Changes in the emission, transport and deposition of aeolian dust have profound effects on regional climate, so that characterizing the lifecycle of dust in observations and improving the representation of dust in global climate models is necessary. A fundamental aspect of characterizing the dust cycle is quantifying surface dust fluxes, yet no spatially explicit estimates of this flux exist for the World’s major source regions. Here we present a novel technique for creating a map of the annual mean emitted dust flux for North Africa based on retrievals of dust storm frequency from the Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the relationship between dust storm frequency and emitted mass flux derived from the output of five models that simulate dust. Our results suggest that 64 (±16)% of all dust emitted from North Africa is from the Bodélé depression, and that 13 (±3)% of the North African dust flux is from a depression lying in the lee of the Aïr and Hoggar Mountains, making this area the second most important region of emission within North Africa.

Beschreibung: Dissolved organic matter (DOM) in marine waters is a complex mixture of compounds and elements that contribute substantially to the global carbon cycle. The large reservoir of dissolved organic carbon (DOC) represents a vital resource for heterotrophic bacteria. Bacteria can utilise, produce, recycle and transform components of the DOM pool, and the physicochemical characteristics of this pool can directly influence bacterial activity; with consequences for nutrient cycling and primary productivity. In the present study we explored bacterial transformation of naturally occurring DOM across an extensive brackish water gradient in the Baltic Sea. Highest DOC utilisation (indicated by decreased DOC concentration) was recorded in the more saline southerly region where waters are characterised by more autochthonous DOM. These sites expressed the lowest bacterial growth efficiency (BGE), whereas in northerly regions, characterised by higher terrestrial and allochthonous DOM, the DOC utilisation was low and BGE was highest. Bacterial processing of the DOM pool in the south resulted in larger molecular weight compounds and compounds associated with secondary terrestrial humic matter being degraded, and a processed DOM pool that was more aromatic in nature and contributed more strongly to water colour; while the opposite was true in the north. Nutrient concentration and stoichiometry and DOM characteristics affected bacterial activity, including metabolic status (BGE), which influenced DOM transformations. Our study highlights dramatic differences in DOM characteristics and microbial carbon cycling in sub-basins of the Baltic Sea. These findings are critical for our understanding of carbon and nutrient biogeochemistry, particularly in light of climate change scenarios.

Beschreibung: Polymetallic seafloor massive sulphide deposits are potential targets for deep-sea mining, but high concentrations of metals (including copper - Cu) may be released during exploitation activities, potentially inducing harmful impact. To determine whether shallow-water shrimp are suitable ecotoxicological proxies for deep-sea hydrothermal vent shrimp the effects of waterborne Cu exposure (3 and 10 days at 0.4 and 4 μM concentrations) in Palaemon elegans, Palaemon serratus, and Palaemon varians were compared with Mirocaris fortunata. Accumulation of Cu and a set of biomarkers were analysed. Results show different responses among congeneric species indicating that it is not appropriate to use shallow-water shrimps as ecotoxicological proxies for deep-water shrimps. During the evolutionary history of these species they were likely subject to different chemical environments which may have induced different molecular/biochemical adaptations/tolerances. Results highlight the importance of analysing effects of deep-sea mining in situ and in local species to adequately assess ecotoxicological effects under natural environmental conditions.

Beschreibung: While the distribution patterns of cold-water corals, such as Paragorgia arborea, have received increasing attention in recent studies, little is known about their in situ activity patterns. In this paper, we examine polyp activity in P. arborea using machine learning techniques to analyze high-resolution time series data and photographs obtained from an autonomous lander cluster deployed in the Stjernsund, Norway. An interactive illustration of the models derived in this paper is provided online as supplementary material. We find that the best predictor of the degree of extension of the coral polyps is current direction with a lag of 3h. Other variables that are not directly associated with water currents, such as temperature and salinity, offer much less information concerning polyp activity. Interestingly, the degree of polyp extension can be predicted more reliably by sampling the laminar flows in the water column above the measurement site than by sampling the more turbulent flows in the direct vicinity of the corals. Our results show that the activity patterns of the P. arborea polyps are governed by the strong tidal current regime of the Stjernsund. It appears that P. arborea does not react to shorter changes in the ambient current regime but instead adjusts its behavior in accordance with the large-scale pattern of the tidal cycle itself in order to optimize nutrient uptake.

Beschreibung: To successfully manage marine fisheries using an ecosystem-based approach, long-term predictions of fish stock development considering changing environmental conditions are necessary. Such predictions can be provided by end-to-end ecosystem models, which couple existing physical and biogeochemical ocean models with newly developed spatially-explicit fish stock models. Typically, individual-based models (IBMs) and models based on advection-diffusion-reaction (ADR) equations are employed for the fish stock models. In this paper, we present a novel fish stock model called SPRAT for end-to-end ecosystem modeling based on population balance equations (PBEs) that combines the advantages of IBMs and ADR models while avoiding their main drawbacks. SPRAT accomplishes this by describing the modeled ecosystem processes from the perspective of individuals while still being based on partial differential equations. We apply the SPRAT model to explore a well-documented regime shift observed on the eastern Scotian Shelf in the 1990s from a cod-dominated to a herring-dominated ecosystem. Model simulations are able to reconcile the observed multitrophic dynamics with documented changes in both fishing pressure and water temperature, followed by a predator–prey reversal that may have impeded recovery of depleted cod stocks. We conclude that our model can be used to generate new hypotheses and test ideas about spatially interacting fish populations, and their joint responses to both environmental and fisheries forcing.

Beschreibung: Highlights • Method and application to improve digital soil maps of silt and clay in China • Within the framework of a DSM approach we derived spatial uncertainties. • Spatial uncertainty is based on randomized decision trees. • Model calibration set is refined by purposive sampling in area of high uncertainty. • Method and map refinement is approved using accuracy and uncertainty measures. Digital soil mapping (DSM) products represent estimates of spatially distributed soil properties. These estimations comprise an element of uncertainty that is not evenly distributed over the area covered by DSM. If we quantify the uncertainty spatially explicit, this information can be used to improve the quality of DSM by optimizing the sampling design. This study follows a DSM approach using a Random Forest regression model, legacy soil samples, and terrain covariates to estimate topsoil silt and clay contents in a small catchment of 4.2 km2 in the Three Gorges Reservoir Area, Central China. We aim (i) to introduce a method to derive spatial uncertainty, and (ii) to improve the initial DSM approaches by additional sampling that is guided by the spatial uncertainty. The proposed uncertainty measure is based on multiple realizations of individual and randomized decision tree models. We used the spatial uncertainty of the initial DSM approaches to stratify the study area and thereby to identify potential sampling areas of high uncertainties. Further, we tested how precisely available legacy samples cover the variability of the covariates within each potential sampling area to define the final sampling area and to apply a purposive sampling design. For the final Random Forest model calibration, we combined the legacy sample set with the additional samples. This uncertainty-driven DSM refinement was evaluated by comparing it to a second approach. In this second approach, the additional samples were replaced by a random sample set of the same size, obtained from the entire study area. For the comparative analysis, external, bootstrap-, and cross-validation was applied. The DSM approach using the uncertainty-driven refinement performed best. The averaged spatial uncertainty was reduced by 31% for silt and by 27% for clay compared to the initial DSM approach. Using external validation, the accuracy increased by the same proportions, while showing an overall accuracy of R2 = 0.59 for silt and R2 = 0.56 for clay.

Beschreibung: Highlights • We modeled landslide susceptibility with statistical and machine learning techniques. • We evaluate performance, predictor importance, and visual appearance of susceptibility maps. • Differences in model prediction performance were for the majority non-significant. • Consequently, landslide modelers may consider selecting modeling techniques based on additional practical criteria. Statistical and now machine learning prediction methods have been gaining popularity in the field of landslide susceptibility modeling. Particularly, these data driven approaches show promise when tackling the challenge of mapping landslide prone areas for large regions, which may not have sufficient geotechnical data to conduct physically-based methods. Currently, there is no best method for empirical susceptibility modeling. Therefore, this study presents a comparison of traditional statistical and novel machine learning models applied for regional scale landslide susceptibility modeling. These methods were evaluated by spatial k-fold cross-validation estimation of the predictive performance, assessment of variable importance for gaining insights into model behavior and by the appearance of the prediction (i.e. susceptibility) map. The modeling techniques applied were logistic regression (GLM), generalized additive models (GAM), weights of evidence (WOE), the support vector machine (SVM), random forest classification (RF), and bootstrap aggregated classification trees (bundling) with penalized discriminant analysis (BPLDA). These modeling methods were tested for three areas in the province of Lower Austria, Austria. The areas are characterized by different geological and morphological settings. Random forest and bundling classification techniques had the overall best predictive performances. However, the performances of all modeling techniques were for the majority not significantly different from each other; depending on the areas of interest, the overall median estimated area under the receiver operating characteristic curve (AUROC) differences ranged from 2.9 to 8.9 percentage points. The overall median estimated true positive rate (TPR) measured at a 10% false positive rate (FPR) differences ranged from 11 to 15pp. The relative importance of each predictor was generally different between the modeling methods. However, slope angle, surface roughness and plan curvature were consistently highly ranked variables. The prediction methods that create splits in the predictors (RF, BPLDA and WOE) resulted in heterogeneous prediction maps full of spatial artifacts. In contrast, the GAM, GLM and SVM produced smooth prediction surfaces. Overall, it is suggested that the framework of this model evaluation approach can be applied to assist in selection of a suitable landslide susceptibility modeling technique.

Beschreibung: Rivers and related freshwater ecosystems are facing increasing natural disturbance and anthropogenic stressors. Understanding the key ecological processes that govern the riverine biota in aquatic ecosystems under multiple pressures has crucial importance. However, there is still insufficient knowledge in quantifying of stressors interactions. Moreover, the understanding of the responses of riverine phytoplankton to multiple stressors is still scarce from catchment aspect. As an interdisciplinary study, the catchment hydrological processes were linked to ecological responses in this study, and we chose phytoplankton functional groups (PFGs) instead of taxonomic classifications of algae to examine their responses to land-use pattern (L), hydrological regime (H), and physicochemical condition (P) across two contrasting hydrological periods (dry, wet). The traits-based phytoplankton functional groups are highly suggested as robust bio-indicators for better understanding the current ecological status. The hydrological regime was described by a matrix indices of hydrological alteration based on the outputs of a well-established ecohydrological model (SWAT). The results from variation partitioning analysis showed that P and H dominate during the dry period and P in high flows. Structural equation models (SEM) showed that the skewness of 7 days discharge emerged as a key driver of H, and had always an indirect effect on functional group TB (benthic diatoms) during both hydrological periods. The functional group M (mainly composed by Microcystis) has directly related to phosphorous in both periods, while indirectly to L of urban area in high flow period, and water bodies in low flow period. This study emphasized that climate change and anthropogenic activities such as altering flow regime and land-use pattern affect directly or indirectly riverine phytoplankton via physicochemical conditions. In addition, our findings highlighted that biomonitoring activities require detailed investigation in different hydrological periods. SEM is recommended for improved understanding of phytoplankton responses to the changing environment, and for future studies to fulfill the increasing demand for sustainable watershed management regarding aquatic biota.

Beschreibung: Methane of various origins is widespread in the sediments of continental margins, representing a key component of the carbon cycle in the ocean. Its occurrence in shallow marine sediments can be linked to the gas hydrate reservoir in the deep sedimentary column. However, this type of methane is difficult to track due to complex reactions occurred during its long distance migration. Porewater geochemical analyses of two ∼7 m piston cores (D17-15 and W01-16) combined with a reaction-transport model were applied to quantify methane-related biogeochemical processes and to explore the linkage of shallow methane to gas hydrate reservoir in the hydrate drilling areas of Shenhu and Dongsha in the South China Sea (SCS). The model results revealed that anaerobic oxidation of methane (AOM) is the predominant biogeochemical process in both cores, consuming approximately 85% and 74% of sulfate in the modeled domain, respectively. The crossplot of dissolve inorganic carbon (DIC) accumulation versus sulfate depletion of the system suggests that methane consumed during the AOM is mainly originated from external methane sources rather than local methanogenesis. Using a δ13CDIC mass balance calculation together with model-derived fractions of different DIC sources, we estimated that the δ13C value of the external methane in core D17-15 is −66.6‰, which is in accordance with the previous reported δ13C values of hydrate-bound methane in the area. These results suggest that methane consumed in shallow sediments in the hydrate drilling areas of the SCS is mainly originated from local gas hydrate reservoir. The proposed approach has the potential to be used to differentiate the sources of methane, which will provide constraints on dynamics of methane in gas hydrate-bearing marine sediments.

Beschreibung: Highlights • Breakdown pressure decreases linearly with increasing temperature. • Reduced effective stress results in low breakdown pressure and multi-fractures. • Low-viscosity CO2 promotes branched fractures. Supercritical CO2 seems to be the most promising non-aqueous fracturing fluid in the unconventional reservoir because it can increase the oil and gas production, save water resources and lower environmental impacts. The temperature effects induced by CO2 injection remain poorly understood in supercritical CO2 fracturing. Hence, we conducted experiments using artificial cubic specimens under the experimental temperatures from 25 °C to 100 °C. The CO2 temperature variation during the testing and the post-experiment fracture morphology were analyzed. In addition, we proposed a fracture mechanics model coupled with thermo-elastic stress to predict the breakdown pressure. The results show that the breakdown pressure of supercritical CO2 fracturing, between 0.55 and 0.84 times of minimum horizontal stress, decreases linearly with temperature. The propagation pressure is also lower than minimum horizontal stress. The thermo-elastic stress induced by cold CO2 injection and the change of CO2 phase can promote the branched or crossing fractures to form a fracture network, especially when the experimental temperature is over 85 °C. With the temperature increasing, SC-CO2 becomes less viscous and can easily permeate into the microcrack tip then to promote fracture propagation. In conclusion, the reduced effective stresses induced by both thermal tensile stress and pore pressure are the main underlying mechanism for lowered breakdown pressure and a fracture network in supercritical CO2 fracturing. A temperature difference between the reservoir and injected CO2 during fracturing affects fracture growth significantly since temperature plays multiple roles in CO2 fracturing.

Beschreibung: Large-scale spatial heterogeneity in fisheries production is predominantly controlled by the availability of zooplankton and benthic organisms, which have a complex relationship with primary production. To investigate how cross-ecosystem differences in these drivers determine fish assemblages and productivity, we constructed a spatially explicit mechanistic model of three fish functional types: forage, large pelagic, and demersal fishes. The model is based on allometric scaling principles, includes basic life cycle transitions, and has trophic interactions between the fishes and with their pelagic and benthic food resources. The model was applied to the global ocean, with plankton food web estimates and ocean conditions from a high-resolution earth system model. Further, a simple representation of fishing was included, and led to moderate matches with total, large pelagic, and demersal catches, including re-creation of observed variations in fish catch spanning two orders of magnitude. Our results highlight several ecologically meaningful model sensitivities. First, coexistence between forage and large pelagic fish in productive regions occurred when forage fish survival is promoted via both favorable metabolic allometry and enhanced predator avoidance in adult forage fish. Second, the prominence of demersal fish is highly sensitive to the efficiency of energy transfer to benthic invertebrates. Third, the latitudinal distribution of the total catch is modulated by the temperature dependence of metabolic rates, with increased sensitivity pushing fish biomass toward the poles. Fourth, forage fish biomass is suppressed by strong top-down controls on temperate and subpolar shelves, where mixed assemblages of large pelagic and demersal fishes exerted high predation rates. Last, spatial differences in the dominance of large pelagics vs. demersals is strongly related to the ratio of pelagic zooplankton production to benthic production. We discuss the potential linkages between model misfits and unresolved processes including movement, spawning phenology, seabird and marine mammal predators, and socioeconomically driven fishing pressure, which are identified as priorities for future model development. Ultimately, the model and analyses herein are intended as a baseline for a robust, mechanistic tool to understand, quantify, and predict global fish biomass and yield, now and in a future dominated by climate change and improved fishing technology.

Beschreibung: The properties, formation, and dissipation of the North Pacific Eastern Subtropical Mode Water (ESTMW), their interannual variability, and impact on spiciness anomalies in the upper permanent pycnocline were investigated using Argo profiling float data in 2005–2015. The core temperature and salinity of ESTMWs were horizontally compensated to a constant density, and core potential density concentrates in a range of 24.5–25.2 kg m−3 with two distinct peaks. ESTMWs showed different spatial distribution and persistence for its core potential density. Denser ESTMWs with a potential density of 24.9–25.2 kg m−3 were formed in winter mixed layer depth maximum centered at 30°N, 140°W and lighter ESTMWs of 24.5–24.9 kg m−3 were formed south and east of it. After formation through shoaling of the winter mixed layer, the former persisted until the following autumn and a small part of it subducted in winter, while the latter dissipated in summer. The formation region of ESTMW corresponded to the summer sea surface density maximum resulting from its poleward sea surface salinity front. Sea surface density maximum maintains weak stratification during summer, preconditioning the deepening of the winter mixed layer and hence the formation of ESTMWs. A relationship between the ESTMW formation region and the summer sea surface density maximum was also found in the North Atlantic and the South Pacific, implying the importance of sea surface salinity fronts and the associated summer sea surface density maximum to ESTMW formation. Interannual variations of ESTMW reflected that of the winter mixed layer in its formation region, and the thickness of ESTMW was related to the Pacific decadal oscillation. ESTMW contributed to the occurrence of spice injection and affected spiciness anomalies in the upper permanent pycnocline through its formation and dissipation.

Beschreibung: Assessing the physicochemical variability of the deeper ocean is currently hampered by limited instrumental time series and proxy records. Bamboo corals (Isididae) form a cosmopolitan family of calcitic deep sea corals that could fill this information gap via geochemical information recorded in their skeletons. Here we evaluate the suitability of high-resolution chemical imaging of bamboo coral skeletons for temperature and nutrient reconstruction. The applied elemental mapping techniques allow to verify the suitability of the chosen transect on the sample section for paleo-reconstructions and enhance the statistical precision of the reconstruction. We measured Mg/Ca via electron microprobe at 1 µm resolution and Ba/Ca via laser ablation ICP-MS at 35 µm resolution in a historic specimen of Keratoisis grayi from the Blake Plateau off Eastern Florida. Long-term growth temperatures of 7.1 ± 3.4 °C (± 2 SD) that are in agreement with recent ambient temperature range can be reconstructed from Mg/Ca ratios provided that anomalously Mg-enriched structural features around the central axis and isolated features related to tissue attachment are avoided for reconstruction. Skeletal Ba/Ca measurements reflect mean seawater barium [Ba]SW concentrations ([Ba]SW = 51 ± 24 nmol kg-1 (± 2 SD)), in agreement with instrumental data (47 nmol kg-1). We show for the first time that Ba/Ca forms concentric structures in a bamboo coral skeleton section. Our investigations suggest that, while bamboo coral skeletons do record environmental parameters in their mean chemical composition, the magnitude of environmental variability reconstructed from high-resolution chemical maps exceeds that expected from instrumental time series. This necessitates additional investigation of the factors driving bamboo coral skeletal composition.

Beschreibung: Sea stars are ecologically important in rocky intertidal habitats where they can play an apex predator role, completely restructuring communities. The recent sea star die-off throughout the eastern Pacific, known as Sea Star Wasting Disease, has prompted a need to understand spatial and temporal patterns of sea star assemblages and the environmental variables that structure these assemblages. We examined spatial and temporal patterns in sea star assemblages (composition and density) across regions in the northern Gulf of Alaska and assessed the role of seven static environmental variables (distance to freshwater inputs, tidewater glacial presence, exposure to wave action, fetch, beach slope, substrate composition, and tidal range) in influencing sea star assemblage structure before and after sea star declines. Environmental variables correlated with sea star distribution can serve as proxies to environmental stressors, such as desiccation, attachment, and wave action. Intertidal sea star surveys were conducted annually from 2005 to 2018 at five sites in each of four regions that were between 100 and 420 km apart across the northern Gulf of Alaska. In the pre-disease years, assemblages were different among regions, correlated mostly to tidewater glacier presence, fetch, and tidal range. The assemblages after wasting disease were different from those before the event with lower diversity and lower density. In addition to these declines, the disease manifested itself at different times across the northern Gulf of Alaska and did not impact all species uniformly across sites. Post sea star wasting, there was a shift in the environmental variables that correlated with sea star structure, resulting in sea star assemblages being highly correlated with slope, fetch, and tidal range. In essence, sea star wasting disease resulted in a shift in the sea star assemblage that is now correlating with a slightly different combination of environmental variables. Understanding the delicate interplay of environmental variables that influence sea star assemblages could expand knowledge of the habitat preferences and tolerance ranges of important and relatively unstudied species within the northern Gulf of Alaska.

Beschreibung: Metabolomics is a systems biology tool useful in the study of the plurality of chemical processes involving intermediates and products of metabolism within an organism, cell or tissue. Food metabolomics can be defined as the application of metabolomics in food systems “from farm to human”. The application of metabolomics technologies has had a significant impact on food research and has further improved the sensitivity demanded by existing food quality/safety legislation. Metabolomics has also opened up new opportunities for biomarker food intake discovery and new metabolite biomarkers identified in body fluids following the consumption of various foods, ingredients, meals, or diets. In nutrition research, metabolomics also aims to understand the correlation between diet or food ingredients and their preventive or health-promoting effects. These exciting possibilities would not be possible in the absence of the huge advances in analytical technologies, including nuclear magnetic resonance and mass spectrometry-based techniques. When coupled with chemometric methods and spectral databases for the statistical analysis and biological interpretation of complex metabolomic data, food metabolomics becomes a powerful investigative tool.

Beschreibung: The period of larval drift into a suitable nursery area is considered to be of great significance for recruitment variability in flatfish. Here, a hydrodynamic model coupled with a Lagrangian particle tracking technique was utilized to study the drift from the first feeding larval stage until time of settlement of Central and Eastern Baltic flounder (Platichthys flesus), originating from spawning in the Baltic Sea deep basins, the Arkona- and Bornholm basin (central Baltic Sea), and the Gdansk deep and Gotland basin (eastern Baltic Sea). We examined the spatio-temporal dynamics of the probability to settle in preferred nursery habitat by detailed drift model simulations. The study suggests that the majority of larvae (89% and 74% for Central- and Eastern Baltic flounder, respectively) drift towards coastal areas and settle at metamorphosis ≤20 km from a sandy habitat enabling further migration to a preferred nursery area, i.e. larval drift seems not to be a major bottleneck in recruitment of flounder spawning in the Baltic Sea deep basins. The drift model results suggest that Central Baltic flounder utilize nursery areas mainly in the central and western Baltic, and in the Kattegat, whereas Eastern Baltic flounder mainly utilize the coast in the central and eastern Baltic. Thus, the two stock components seem to use different nursery areas following settlement. Further, in accordance with the “nursery size hypothesis”, the model demonstrates that larvae from the Bornholm basin, utilizing areas with extensive distribution of preferred nursery habitat, display the highest relative successful transport to nursery grounds until settling (72% of successfully settled larvae), suggesting that spawning in the Bornholm Basin is of great importance for stock recruitment of deep basin spawning Baltic flounder.

Beschreibung: Highlights: • Recruitment indicator: egg survival probability vs. “reproductive volume concept”. • Traditional sampling methodology unable to resolve spatial egg distributions. • Predominance of self-sustaining stock components and low connectivity. • Egg buoyancy and topographic features: limitation of cod egg transport. • Sedimentation as a new mortality source of eastern Baltic cod eggs. Abstract: In the highly variable environment of the Baltic Sea two genetically distinct cod stocks exist, one west of the island of Bornholm, which is referred to as the western stock, and one to the east of Bornholm, the eastern stock. A hydrodynamic model combined with a Lagrangian particle tracking technique was utilised to provide spatially and temporally resolved long-term information on environmentally-related (i) spawning habitat size, (ii) egg/yolk-sac larval survival, (iii) separation of causes of mortality, and (iv) connectivity between spawning areas of eastern Baltic cod. Simulations were performed to quantify processes generating heterogeneity in spatial distribution of cod eggs and yolk sac larvae up to the first-feeding stage. The spatial extent of cod eggs represented as virtual drifters is primarily determined by oxygen and salinity conditions at spawning, which define the habitat requirement to which cod’s physiology is suited for egg development. The highest habitat suitability occurred in the Bornholm Basin, followed by the Gdansk Deep, while relatively low habitat suitability was obtained for the Arkona and the Gotland Basin. During drift egg and yolk sac larval survival is to a large extent affected by sedimentation. Eggs initially released in the western spawning grounds (Arkona and Bornholm Basin) were more affected by sedimentation than those released in the eastern spawning grounds (Gdansk Deep and Gotland Basin). Highest relative survival of eastern Baltic cod eggs occurred in the Bornholm Basin, with a pronounced decrease towards the Gdansk Deep and the Gotland Basin. Relatively low survival rates in the Gdansk Deep and in the Gotland Basin were attributable to oxygen-dependent mortality. Low oxygen content had almost no impact on survival in the Arkona Basin. For all spawning areas temperature dependent mortality was only evident after severe winters. Egg buoyancy in relation to topographic features like bottom sills and strong bottom slopes could appear as a barrier for the transport of Baltic cod eggs and yolk sac larvae and could potentially limit the connectivity of Baltic cod early life stages between the different basins in the western and eastern Baltic Sea. The possibility of an eastward directed transport up to the first-feeding larval stage exists only for eggs and yolk sac larvae at high buoyancy levels, suggesting that dispersal of early life stages between these spawning areas is limited.

Beschreibung: Highlights: • Model output indicates high connectivity between the eastern Baltic cod nursery grounds. • Variability of spatial juvenile distribution patterns affected by flow dynamics. • Trend of simulated occupied juvenile cod habitat have been declining over the last decades. • Condition of juveniles suggests density-dependence due to hypoxia-related decrease in suitable habitat. • Baltic cod recruitment indicator: habitat availability for juvenile settlement as a factor for recruitment. Abstract: In this study the drift of eastern Baltic cod larvae and juveniles spawned within the historical eastern Baltic cod spawning grounds was investigated by detailed drift model simulations for the years 1971–2010, to examine the spatio-temporal dynamics of environmental suitability in the nursery areas of juvenile cod settlement. The results of the long-term model scenario runs, where juvenile cod were treated as simulated passively drifting particles, enabled us to find strong indications for long-term variations of settlement and potentially the reproduction success of the historically important eastern Baltic cod nursery grounds. Only low proportions of juveniles hatched in the Arkona Basin and in the Gotland Basin were able to settle in their respective spawning ground. Ocean currents were either unfavorable for the juveniles to reach suitable habitats or transported the juveniles to nursery grounds of neighboring subdivisions. Juveniles which hatched in the Bornholm Basin were most widely dispersed and showed the highest settlement probability, while the second highest settlement probability and horizontal dispersal was observed for juveniles originating from the Gdansk Deep. In a long-term perspective, wind-driven transport of larvae/juveniles positively affected the settlement success predominately in the Bornholm Basin and in the Bay of Gdansk. The Bornholm Basin has the potential to contribute on average 54% and the Bay of Gdansk 11% to the production of juveniles in the Baltic Sea. Furthermore, transport of juveniles surviving to the age of settlement with origin in the Bornholm Basin contributed on average 13 and 11% to the total settlement in the Arkona Basin and in the Gdansk Deep, respectively. The time-series of the simulated occupied juvenile cod habitat in the Bornholm Basin and in the Gdansk Deep showed a similar declining trend as the Fulton’s K condition factor of demersal 1-group cod, which may confirm the importance of oxygen-dependent habitat availability and its effect on density dependence as a process relevant for recruitment success.

Beschreibung: Highlights: • Dispersal patterns reflect basin-like structure. • Decadal and spatial variability of dispersal patterns • Spatial differences in stability of dispersal patterns • Conceptual tool to support genetic and ecological studies • Datasets freely available for application to other species Abstract: Connectivity between different populations of a species is a central parameter in the fields of ecology and evolutionary biology. We here provided decadally, regionally, and depth layer resolved information on connectivity and dispersal patterns for the entire Baltic Sea as a tool for supporting population genetic and ecological studies. The general method to assess dispersal used was bio-physical modelling, which is suitable for biological dispersal that is highly influenced by the physical water transport in ocean circulation. The results were assessed from Lagrangian particle tracking using ocean circulation model outputs. Generally, for the whole Baltic Sea as well as for all subareas, we observed persistent patterns of dispersal that reflected the basin-like structure of the Baltic Sea, with less transport between the basins. At the same time, dispersal distance and in extension, local retention versus dispersal of particles to other sub-areas, varied considerably over four decades (1970–2010) and among regions within the Baltic Sea, corresponding to a range from high connectivity to partial dispersal barriers. Based on the example of Eastern Baltic cod we then investigated how our dispersal distance datasets can serve as a tool to assess dispersal and the expected connectivity among different populations of a species, as long as some biological information is available. For example, our finding of high dispersal of particles from the Bornholm Basin to the other Eastern Baltic basins could help to explain recent results indicating lack of genetic differentiation of cod across the eastern Baltic Sea. Our results also indicate that the shift in spawning time observed in cod over the past decades and the resulting exposure of eggs and larvae in the water column to a time of the year with a different current regime has likely affected egg and larval export. Finally, our case study also demonstrates how inter-annual variability of ocean current speed and direction at the time of peak reproduction is likely to affect the connectivity among the subareas in the Baltic. To conclude, connectivity datasets from this study are freely available, and can represent a powerful tool to apply in evolutionary and ecological studies of a variety of species in the Baltic Sea.

Beschreibung: In the Baltic Sea, two genetically distinct cod populations occur, the eastern and the western Baltic cod. Since 2006, cod abundance has increased substantially in the Arkona Basin (SD 24), the potential mixing area between the two stocks management areas, presumably due to spill-over from the eastern stock. In this study, the spatio-temporal dynamics of stock mixing were analysed using shape analysis of archived otoliths. Further, the impact of eastern cod immigration on recruitment in the western Baltic Sea was investigated using hydrographic drift modelling. The percentage of eastern Baltic cod in the Arkona Basin increased from ca. 30% before 2005 to 〉80% in recent years. Geographic patterns in stock mixing with a pronounced east–west trend suggest that immigration occurs north of Bornholm, but propagates throughout the Arkona Basin. The immigration cannot be attributed to spawning migration, as no seasonal trend in stock mixing was observed. Based on environmental threshold levels for egg survival and time-series of hydrography data, the habitat suitable for successful spawning of eastern cod was estimated to range between 20 and 50% of the maximum possible habitat size, limited by primarily low salinity. Best conditions occurred irregularly in May–end June, interspersed with years where successful spawning was virtually impossible. Using a coupled hydrodynamic modelling and particle-tracking approach, the drift and survival of drifters representing eastern cod eggs was estimated. On average, 19% of the drifters in the Arkona Basin survive to the end of the yolk-sac stage, with mortality primarily after bottom contact due to low salinity. The general drift direction of the surviving larvae was towards the east. Therefore, it is the immigration of eastern cod, rather than larval transport, that contributes to cod recruitment in the western Baltic Sea.

Beschreibung: The Taupo Volcanic Zone (TVZ) in the North Island of New Zealand is one of the world’s most spectacularand productive areas of Quaternary silicic volcanism and geothermal manifestations. The TVZ is only thelatest manifestation of NNE–SSW-orientated arcs that have migrated in step-wise fashion to the SSE overthe past ca. 16 Ma. The TVZ began erupting around 2 Ma, with early andesitic volcanism being joined andrapidly swamped by voluminous rhyolitic volcanism. The zone shows a pronounced segmentation intonorthern and southern extremities with andesite composite cones, no calderas and only limited vent-hosted geothermal systems, and a 125 km long rhyolite-dominated central segment. About four timesas much magma is trapped at depth below the central TVZ than is erupted, feeding heat, volatiles andchemicals into 23 geothermal systems with a total of ca. 4.2 GW thermal energy release. The modern(post-61 ka) TVZ is an actively rifting arc, widening at 7 mm/year at the south end to 15 mm/year at theBay of Plenty coastline, with an associated zone of young to active faulting (Taupo Fault Belt: TFB, orthe Taupo Rift), but the axes of the modern TFB and TVZ are offset by 15–20 km through much of thecentral TVZ. Although there is a dominant NNE–SSW tectonic grain within the central TVZ, there arealso influences of deeper basement structures that sometimes extend outside the limits of the zone,such as NW–SE, arc-perpendicular accommodation zones linking local domains of extension as well asN–S orientated structures related to the Hauraki Rift that may control fluid flow into the roots of thegeothermal systems. Models for the geothermal systems favour either a source in a relatively shallowlocalised magmatic intrusion (e.g., Kawerau, Ngatamariki) or treat the systems as reflecting large-scalefluid dynamical instabilities from an evenly heated ‘hot plate’ at ∼7 km depth. Where controls from datingof host lithologies are available, systems at Kawerau and Ngatamariki are seen to represent renewedactivity superimposed on a fossil system fed by past intrusions, and it is unclear what is meant by thelifetime of any single geothermal system. TVZ geothermal systems appear in turn to react too sluggishly torespond to disruptive episodes of volcanism, and recover within geologically short periods of time, as seenat Waimangu and Taupo. In the central TVZ, there are complex inter-relationships between volcanism,magmatism, and tectonism. Magmatism and volcanism are obviously linked, but it is uncertain whyintense magmatism at Taupo and Okataina should yield voluminous rhyolite volcanism, whereas moreintense magmatism in the Taupo-Reporoa Basin has not yielded significant silicic volcanism but insteadfeeds multiple large geothermal systems. The central TVZ is unique for an arc segment in the intensityof its magmatic-volcanic-geothermal flux (matching the Yellowstone system), and the cause(s) of thisuniqueness are not yet established. Any explanation needs to address the segmented nature of the zone,and why the thermal flux should be so geographically and temporally constrained.

Beschreibung: Rare earth elements and yttrium (REY) are often used as proxies for (paleo)environmental conditions and for the reconstruction of element sources and transport pathways. Many geological systems are well described with respect to the behavior of REY but deep-sea sediments with their manifold processes impacting the sediment during early diagenesis leave some questions about the origin and development of the shale-normalized REY (REYSN) patterns unanswered. Here we report REY data for sediment solid phase and pore water from the upper 10 m of deep-sea sediments from the Clarion Clipperton Zone (CCZ) in the central equatorial Pacific. The solid-phase REY profiles show highest concentrations at depth below 5–8 m. The REYSN patterns show an enrichment in middle REY (MREY) (LaSN/GdSN between 0.35 and 0.60; GdSN/YbSN between 1.19 and 1.47) and either no or negative CeSN and YSN anomalies (i.e. chondritic to sub-chondritic Y/Ho ratios between 24.7 and 28.7). Based on correlation analyses of bulk sediment element concentrations and sequential extractions, we suggest that a Ca phosphate phase controls the distribution and the patterns of REY in these silty clay pelagic sediments rich in siliceous ooze. The MREY enrichment develops at the sediment-water interface and intensifies systematically with depth. The negative CeSN anomaly intensifies with depth possibly because Ce is mostly bound to Mn- and Fe-(oxyhydr)oxides. Therefore, Ce concentrations remain relatively constant throughout the sediment core, while its trivalent REY neighbors are mostly hosted by the Ca phosphate phase that continuously incorporates REY from ambient pore waters. The non-redox-sensitive trivalent REY concentrations increase with depth, producing or enhancing a negative CeSN anomaly through coupled substitution of REY3+ and Na+ for Ca2+. The solid-phase REYSN pattern is therefore determined by the pore-water REYSN pattern and not suitable for paleoceanographic interpretation. The similarity of the pore-water and solid-phase REYSN patterns suggests, however, that only minor fractionation occurs during REY incorporation into the Ca phosphate crystal structure.

Beschreibung: It is well-recognized that multiple components, the majority of which are secondary metabolites and carbohydrates, collectively contribute to the therapeutic effects of herbal medicines. The chemical characterization of herbal medicines has focused extensively on secondary metabolites but has largely overlooked carbohydrates. Here, we proposed an integrated chromatographic technique based targeted glycomics and untargeted metabolomics strategy simultaneously determining carbohydrates and secondary metabolites for the overall chemical profiling of herbal medicines; this strategy was successfully exemplified in an investigation of processing chemistry of Rehmanniae Radix (RR), a Chinese medicinal herb. It was demonstrated that the integrated strategy holistically illuminated the variations in the glycome and metabolome of RR samples processed by the traditionally-adopted nine cycles of steaming and drying, and further elucidated the processing-induced chemical transformation mechanisms of carbohydrates and secondary metabolites, and thereby revealed the inherent chemical connections between carbohydrates and secondary metabolites. The result suggested that the proposed strategy meets the technical demands for the overall chemical characterization of herbal medicines, and therefore could serve as a powerful tool for deciphering the scientific basis of herbal medicines.

Beschreibung: In this work, 18 gluten-free flours (prepared from cereals, pseudocereals and legumes), differing in pigmentation, were screened for their phenolic profiles, cooked and, then, subjected to digestion and large intestinal fermentation in vitro. A combined targeted/untargeted metabolomic approach was used to elucidate the microbial biotransformation processes of polyphenols following digestion. This preliminary work demonstrated an increase in 3,5-dihydroxybenzoic acid (on average from 0.67 up to 1.30 μmol/g dry matter) throughout large intestinal fermentation of pseudocereals (esp. quinoa), due to their high alkylresorcinol contents. Isoflavones were converted into equol- or O-desmethylangolensin- derivatives, whereas anthocyanins were degraded into lower-molecular-weight phenolics (i.e., protocatechuic aldehyde and 4-hydroxybenzoic acid, with the latter exhibiting the highest increase over time). A decreasing trend was observed for antioxidant activities (i.e., FRAP and ORAC values) moving from digested to faecal fermented samples. These findings highlight that gluten-free flours are able to deliver bioaccessible polyphenols to the colon.

Beschreibung: Highlights • Active tectonics in Sicilian Channel • Analogue models of transcurrent structures • 3D fault pattern reconstruction Seismo-stratigraphic and structural analysis of a large number of multichannel seismic reflection profiles acquired in the northern part of the Sicilian Channel allowed a 3-D reconstruction of a regional NS-trending transfer zone which displays a transcurrent tectonic regime, and that is of broad relevance for its seismotectonic and geodynamic implications. It is constituted of two major transcurrent faults delimiting a 30-km-wide, mostly undeformed basin. The western fault (Capo Granitola) does not show clear evidence of present-day tectonic activity, and toward the south it is connected with the volcanic area of the Graham Bank. The eastern fault (Sciacca) is structurally more complex, showing active deformation at the sea-floor, particularly evident along the Nerita Bank. The Sciacca Fault is constituted of a master and splay faults compatible with a right-lateral kinematics. Sciacca Fault is superimposed on an inherited weakness zone (a Mesozoic carbonate ramp), which borders to the east a 2.5-km-thick Plio-Quaternary basin, and that was reactivated during the Pliocene. A set of scaled claybox analogue models was carried out in order to better understand the tectonic processes that led to the structural setting displayed by seismic data. Tectonic structures and uplift/subsidence patterns generated by the models are compatible with the 3-D model obtained from seismic reflection profiles. The best fit between the tectonic setting deriving from the interpretation of seismic profiles and the analogue models was obtained considering a right-lateral movement for the Sciacca Fault. Nevertheless, the stress field in the study area derived from GPS measurements does not support the present-day modelled right-lateral kinematics along the Sciacca Fault. Moreover, seismic events along this fault show focal mechanisms with a left-lateral component. We ascribe the slip change along the Sciacca Fault, from a right-lateral transcurrent regime to the present-day left-lateral kinematics to a change of principal horizontal stress direction starting from Late Pliocene.

Beschreibung: Highlights • Leaching rates of BFRs were controlled by diffusion within the plastic matrix. • The diffusion coefficients of BFRs in ABS ranged from 10−28.30 to 10−20.84 m2 s−1 • The activation energies for diffusion of BFRs ranged from 64.1 to 131.8 kJ mol−1 • Diffusion coefficients of BFRs in plastic matrix depend on their molecular sizes. • Diffusion coefficients show dependence on the plastic's glass transition temperature. Microplastics (〈5 mm) are increasingly detected in aquatic environment, and the high levels of brominated flame retardants (BFRs) contained in them can potentially impact water quality. This study characterized the release kinetics of polybrominated diphenyl ethers (PBDEs) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) from millimeter-sized microplastic pellets in water at environmentally relevant temperatures. Leaching rates of BFRs from the microplastic pellets made of acrylonitrile butadiene styrene (ABS) were found to be controlled by their diffusion within the plastic matrix, and their diffusion coefficients (D) in the plastic matrices ranged from 10−28.30 to 10−20.84 m2 s−1. The apparent activation energies of the BFRs’ diffusion coefficients were estimated to be in the range of 64.1–131.8 kJ mol−1 based on their temperature dependence and the Arrhenius equation. The diffusion coefficients of the BFRs decrease with their molecular diameters, while the activation energies for diffusion increase with the molecular diameters, which are indicative of significant steric hindrance for BFR diffusion within the plastic matrices. A semi-empirical linear relationship was observed between Log10D and the glass transition temperature (Tg) of plastics, which allows prediction of the diffusion coefficients of BFRs in other types of microplastics commonly found in marine environment. The half-lives of BFR leaching (i.e., 50% depletion) from the microplastic pellets would range from tens of thousands to hundreds of billions of years at ambient temperatures if their physical and chemical structures could remain intact. Although the release fluxes of BFRs from microplastics are extremely low under the model conditions, a range of physical and chemical processes in the natural environment and the digestive systems of organisms that ingested them could potentially accelerate their leaching by causing breakdown and swelling of the plastic matrices.

Beschreibung: Highlights • A structural map of the northern part of the Capo Granitola-Sciacca strike-slip Fault Zone (Sicilian Channel) has been produced. • Numerous magmatic manifestations in addition to those already known in the Graham and Terrible banks, have been recognized. • A relationship between magmatism and structures associated with the Capo Granitola-Sciacca Fault Zone, has been documented. • A mechanism of non-plume origin is proposed for the magmatism observed in the study area. The tectonic framework of the northern sector of the Capo Granitola-Sciacca Fault Zone (CGSFZ), a NNE-oriented lithospheric strike-slip fault zone located in the Sicilian Channel (southern Italy), has been reconstructed with the aim to clarify the relationships between geometry and kinematics of the structures and the occurrence and distribution of the magmatic manifestations observed in the area. This has been achieved by the interpretation of a large dataset composed of 2-D multichannel seismic profiles, Chirp profiles, magnetic data and borehole information. In addition to the volcanic edifices known in the Graham and Terribile banks, this study has allowed to recognize several other magmatic manifestations. The magmatic occurrences consist of small volcanic cones, buried magma ascents and potential igneous sills. The CGSFZ is bounded by two strike-slip fault systems, the Capo Granitola Fault System (CGFS) to the west and the Sciacca Fault System (SFS) to the east, dominated by positive flower structures generated by tectonic inversion of NNE-oriented late Miocene extensional faults. Only the southern part of the CGFS shows the presence of a sub-vertical, N-S oriented strike-slip master fault. The sector between the two fault systems does not show a significant Pliocene-Quaternary tectonic deformation, except for its southern part hosting the Terribile Bank, which is dissected by WNW to NW-trending normal faults developed during late Miocene and later reactivated. This set of faults is currently active at the Terribile Bank, whereas is buried by Pliocene-Quaternary deposits in the central and northern sectors of the CGSFZ. The observed magmatism is driven by a mechanism of non-plume origin. Magmas have used as open paths the faults of the CGFS and SFS, which cut the whole lithosphere reaching the asthenosphere and producing partial melting by simple pressure release. Most of the magmatism develops along the strike-slip master fault associated with the CGFS and the normal faults affecting the Terribile Bank. The magmatic feeding of the Terribile Bank would be related to lateral magma migration coming from the structures of the SFS, which would use the open pathways represented by active normal faults. In the central-northern part of the CGSFZ, magmas migrate upward along lithospheric faults, then move laterally and rise toward the surface through NNE and NW-trending buried normal faults. These late Miocene faults do not reach the surface, and this may have favoured the emplacement of igneous sills, which in turn may explain the observed volcanic centres.

Beschreibung: Highlights • Seismic reflection profiles evidence tectonic inversion and active strike-slip faults offshore SW Sicily foreland • Pliocene-Quaternary transpressional inversion of Late Miocene extensional basins • Transpressional fold growth rates were high in Latest Miocene-Pliocene and decreased during Quaternary Joint analysis of high-penetration multi-channel and high-resolution single-channel seismic reflection profiles, calibrated by deep well boreholes, allowed a detailed reconstruction of the Late Miocene to Recent tectonic history of the Capo Granitola and Sciacca fault systems offshore southwestern Sicily. These two fault arrays are part of a regional system of transcurrent faults that dissect the foreland block in front of the Neogene Sicilian fold and thrust belt. The Capo Granitola and Sciacca faults are thought to reactivate inherited Mesozoic to Miocene normal faults developed on the northern continental margin of Africa. During Latest Miocene-Pliocene, the two ~NNE-SSW striking faults were active in left transpression, which inverted Late Miocene extensional half-grabens and created push-up ridges along both systems. Tectonic activity decreased during the Pleistocene, but transpressional folds deform Middle-Late Pleistocene sediments as well, suggesting that the two fault systems are active. The ~40 km long longitudinal amplitude profile of 1st order folds (Capo Granitola and Sciacca anticlines) shows ~15–20 km bell-shaped undulations that represents 2nd order folds. The length of these undulations together with the map pattern of faults allowed to divide the CGFS and SFS into two segments, northern and southern, respectively. Total uplift of the Sciacca Anticline is twice than the uplift of the Capo Granitola Anticline. Incremental fold growth rates decreased during time from 0.22 mm/yr (Capo Granitola Anticline) and 0.44 mm/yr (Sciacca Anticline) in the Pliocene, to 0.07 and 0.22 mm/yr, respectively, during the last ~1.8 Ma.

Beschreibung: Highlights • Diffusion coefficients of HOCs in PE/PP were measured. • Desorption of HOCs from PE/PP films was measured. • A desorption model for HOCs using mass transfer Biot number was developed. • Experimental desorption agreed well with model prediction. • The desorption model was used to estimate desorption half-lives of HOCs. To evaluate rate of migration from plastic debris, desorption of model hydrophobic organic chemicals (HOCs) from polyethylene (PE)/polypropylene (PP) films to water was measured using PE/PP films homogeneously loaded with the HOCs. The HOCs fractions remaining in the PE/PP films were compared with those predicted using a model characterized by the mass transfer Biot number. The experimental data agreed with the model simulation, indicating that HOCs desorption from plastic particles can generally be described by the model. For hexachlorocyclohexanes with lower plastic-water partition coefficients, desorption was dominated by diffusion in the plastic film, whereas desorption of chlorinated benzenes with higher partition coefficients was determined by diffusion in the aqueous boundary layer. Evaluation of the fraction of HOCs remaining in plastic films with respect to film thickness and desorption time showed that the partition coefficient between plastic and water is the most important parameter influencing the desorption half-life.

Beschreibung: Aquatic microbial communities are central to biogeochemical processes that maintain Earth’s habitability. However, there is a significant paucity of data collected from these species in their natural environment. To address this, a suite of ocean-deployable sampling and sensing instrumentation has been developed to retrieve, archive and analyse water samples and their microbial fraction using state of the art genetic assays. Recent deployments have shed new light onto the role microbes play in essential ocean processes and highlight the risks they may pose to coastal populations. Although current designs are generally too large, complex and expensive for widespread use, a host of emerging bio-analytical technologies have the potential to revolutionise this field and open new possibilities in aquatic microbial metrology.

Beschreibung: Highlights • Amplitudes of near-field waves generated by highly mobile flows are independent of slide volume for a given reservoir depth. • Depth-limited breaking is the primary control on the wave amplitude as waves propagate into the far-field. • Effective time and length of forcing are important factors that influence momentum transfer. Landslides into water can generate massive tsunamis which are major natural hazards in coastal regions. In this study, waves were generated in a series of 41 laboratory experiments by releasing 4 different slide volumes ranging from 0.1-0.4 m3 of highly mobile material down a 6.73 m long slope into a reservoir of depth varying from 0.15-0.65 m, to achieve a wide range of dimensionless landslide parameter values. Water is used as the sliding material and with zero internal shear strength it is representative of the upper limit of high landslide mobility. The slide characteristics of thickness and velocity were measured at impact using high speed cameras and the time series of the resulting changes in water surface elevation were measured using nine wave probes along the 33.8 m long flume. The experimental results indicate that in the near-field the maximum wave amplitude is dependent on the landslide thickness and velocity and is relatively independent of the reservoir water depth. As waves propagate to the far-field, the depth-limited breaking reduces the wave amplitude, such that the maximum wave amplitude is highly dependent on the reservoir depth. The wave breaking limit, which differentiates the breaking from the non-breaking waves, is defined by the relationship am/h = 0.6 that is very closely adhered to for all source volumes and reservoir depths. The time and length over which the waves are generated are determined from the digital imagery, and are used to describe the scales of the momentum transfer. These observations are compared with previously published empirical and theoretical equations for granular landslides and positively buoyant avalanches, indicating that water is a useful source material for simulating highly mobile landslides. Since these parameters are difficult to obtain in field cases, a simplification of the theoretical equation is presented and this yields reasonable results for the maximum wave amplitude generated by slides with high mobility.

Beschreibung: The present study describes the calcium adsorption behavior of clays exhibiting distinct mineralogical composition. The adsorption characteristics were determined using conventional batch-equilibrium sorption method, and different theoretical models were applied to describe the equilibrium sorption isotherms. The variation in calcium adsorption capacity was determined as a function of clay mineralogy, temperature and pore fluid chemistry. Further, the thermodynamic parameters were also calculated to describe the nature of adsorption mechanisms. Significant variation in calcium adsorption potential was observed among the clays, primarily attributed to their mineralogical diversities and related unique surface charge properties. The adsorption density escalated with rise in calcium concentration, temperature and pH of the adsorption system. These observations can be attributed to surface charge modifications and mineral dissolution properties of the clays, which in turn resulted in higher electro-negativity of the clay surface and thereby enhancing the affinity for calcium ions.

Beschreibung: We explore a novel approach towards quantification of paleo-ecological signals from non-analogue microfossil assemblages by quantifying relations between assemblages and high-quality geochemical and sedimentological data from sedimentary archives. We test this approach using one group of microfossils, the organic cysts of dinoflagellates (dinocysts), which are widely used in shelf and open marine settings for biostratigraphy and reconstructions of past environments and environmental change. Similar to other microfossil groups, dinocysts can be used to reconstruct environments with relatively high confidence for recent time periods, as species affinities can be derived from observational and instrumental data. In the absence of such data, the ecology of extinct species is much less certain and as a result reconstructions in deep time are often limited to qualitative interpretations. To explore if quantitative empirical relations between extinct dinocysts and high-quality geochemical data can be established, we study a major event of climate change, the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma ago). The PETM is a particularly suitable period for this exercise as there is a multitude of large environmental perturbations associated with the transient global warming, such as deoxygenation, sea level rise and an accelerated hydrological cycle. The synthesized published dataset exhibits better spatial and temporal coverage compared to any other period in deep time. We extract empirical relations for the abundance of previously proposed paleoecological groups as a function of independent environmental proxies for example, sea surface temperature and terrestrial organic matter input. The results unequivocally illustrate that many dinocysts show relations to several of the reconstructed environmental variables. Notably, we show that one genus (Apectodinium) and an ecogroup (epicystal Goniodomidae) required sea surface temperatures in excess of 20 °C, and 25 °C, respectively, while one species (Florentinia reichartii) was only abundant between 30 and 35 °C. Other groups apparently favored either a limited (Spiniferites) or high (Senegalinium) terrestrial input to the study site, relating to salinity, nutrient levels or suspended sediment load (i.e. murkiness). Crucially, our work shows that the validation and quantification of ecological signals by independent environmental proxy data provides the opportunity to extract more quantitative information from a wide range of (non-analogue) microfossil assemblages. While this approach is not limited to any specific group of microfossils (or macrofossils), we stress that proper calibration datasets, high-quality sedimentological and geochemical proxy records, are needed and should ideally have decent geographical coverage and include one or more environmental perturbations. Using this approach such empirical relations can be established for a wide range of microfossil groups that have highly complementary geological records, which increases the value of existing data and ensures future application of microfossil-based paleoecology.

Beschreibung: Highlights • Six Spiniferites species from Thanetian and Danian sediments are described. • All species evidence biostratigraphic relevance across the North and Norwegian Sea. • Species provincialism is evidence for regional paleoenvironmental changes within the basin. Industrial palynological studies of the Paleocene of North Sea and Norwegian Sea basins over several decades have led to the consistent recognition of six distinctive species of organic-walled dinoflagellate cyst genus Spiniferites. These species, however, have not previously been formally described, a situation that we remedy herein. Hence, we propose the new species Spiniferites fentonii, Spiniferites rhomboideus, Spiniferites truncatus, Spiniferites sabulus, Spiniferites kirschii and Spiniferites dolichoidus. These new species have distinctive morphological features that separate them, from other species, both of Spiniferites and other genera. Some of the new species are very useful stratigraphic markers across north-western Europe. The material described is from the early Thanetian Lista Formation and a late Danian interval including the basal Maureen Formation and parts of the Våle Formation. The new species have not been observed in the Selandian (between the Danian and Thanetian), and Spiniferites diversity during that stage seems to have been lower in general across the study area; this was probably related to regional environmental changes. The stratigraphic range of the new species is used in combination with other known markers to increase stratigraphic resolution across the region.

Beschreibung: We study multiphase and multiscale mechanical properties of the Gondwana shale samples obtained from the Raniganj Formation of central and eastern India. The mechanical properties of black and gray shale samples cored perpendicular to the bedding plane direction are analyzed across nano-to-micro scales using the nanoindentation method. We characterize the multiphase structure of the two shales in terms of three mechanical phases–quartz/feldspar/pyrite, organic matter, and kaolinite–and use that to explain the heterogeneous elastoplastic behavior observed during nanoindentation. We quantify the fracture toughness of black and gray shales at microscale using our modified energy method, which relates the energy released during a pop-in event to a radial fracture model. We extend the deconvolution approach over multiple properties to estimate the uncertainty in multiphase structure and phase volume fractions. We used the viscosity-toughness scaling analysis to study the difference in hydraulic fracturing behavior of the black and gray shales. We show the influence of nano- and micro-scale multiphase mineralogical properties on characteristic length, time and pressure scales of fracture propagation at mesoscale.

Beschreibung: Highlights • Nisyros (rhyo)dacites are unhybridized melts extracted from a cumulate mush. • The peritectic crystallisation of amphibole buffers the composition of the melts. • High compatible element contents emphasise the role of cumulate resorption. • Crustal melting is not required to generate rhyolitic melts. • Peritectic melts are a common global endmember in the monotonous intermediates. The generation of continental crust of intermediate composition occurs predominantly in convergent margin settings, yet the mechanisms by which felsic, calc-alkaline arc magmas are generated remain poorly understood. Magma mixing appears to be a common process in voluminous intermediate arc rocks but the composition of the felsic mixing endmember is typically obscured by the mixing process. We investigate a suite of porphyritic (rhyo)dacitic magmas (65–72 wt.% SiO2) from Nisyros, a young stratovolcano in the Aegean arc, Greece. These magmas are not affected by shallow process such as hybridisation or crystal-melt segregation and thus offer a valuable insight into the origin of felsic melts at convergent margins. We find that the Nisyros (rhyo)dacites form through a reaction in which earlier-formed wehrlite cumulates in the deep arc crust react with melts to form amphibole. This implies that melt major element compositions are effectively buffered by a low-variance mineral assemblage to follow this peritectic boundary such that the silica content of melts extracted from the deep crustal hot zone is controlled by the amount of amphibole crystallised. The resorption of cumulates is pivotal in imparting a distinct trace element signature that is decoupled from major element systematics. For example, high compatible element contents and a strong amphibole signature (low Y and Dy/Yb) cannot be captured by simple crystallisation models and require cumulate resorption. Variable radiogenic isotope systematics indicate minor crustal contamination although assimilation is not proportional to silica content and hence not a main driving force behind the generation of felsic melts. Instead, the Nisyros (rhyo)dacites formed through melt-cumulate reaction processes prior to emplacement as mush bodies at shallow depth and partial eruption. Magma mixing only becomes an important process in the youngest unit on Nisyros. On a global scale, peritectic boundary melts are rarely sampled in the whole rock or melt inclusion record. Conversely, peritectic boundary melts do form a suitable felsic mixing endmember for the generation of voluminous “monotonous intermediate” magmas.

Beschreibung: Highlights • We build a framework for the fracture testing of gas shale at the microscopic scale. • We extend the scratch fracture model to transversely isotropic materials. • We observe a toughening behavior of gas shale at the microscopic scale. • Some toughening mechanisms observed are particle pull-out and front roughening. We investigate the fracture properties of organic-rich shale at the microscopic scale by coupling advanced imaging techniques, fracture mechanics and micro-scale mechanical testing methods. We study three shale systems: Toarcian (Paris Basin, France), and Lower and Upper Woodford shale (Oklahoma, US). A material preparation procedure is designed so as to visualize the microstructure. Optical microscopy and scanning electron microscopy reveal a porous granular fabric with the grain size ranging from 30 to 100 μm as well as micron-sized air voids. Microscopic scratch tests are carried out, during which a stylus is pushed across the surface of a material under a prescribed monotonically increasing vertical load. We develop a fracture mechanics approach that takes into account the heterogeneity and anisotropy of gas shale. The microscopic scratch toughness predicted by the scratch fracture model is 2.35–2.98 MPa , which is two times higher than the macroscopic fracture toughness. A microscopic examination of the fracture surface reveals toughening mechanisms such as particle pull out, crack front roughening and crack bridging. The methodology presented is new and will pave the way toward a mechanistic physics-based understanding of the fracture behavior of gas shale at multiple length scales. In turn, this will accelerate the design of optimum and efficient schemes to extract natural gas from unconventional shale.

Beschreibung: Sustaining a network of connected fractures is critical to the long-term success of Enhanced Geothermal Systems (EGS). In this study, the effects of coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes on fracture aperture and permeability were examined by conducting a series of flow-through experiments on artificially-fractured granite specimens at effective stresses of 5 MPa to 36 MPa, rock temperatures of 25 °C and 130 °C, and injected fluid temperatures of 25 °C, 75 °C, and 130° C. The higher fracture closure rates observed at higher effective stresses and the incomplete recovery of fracture permeability and hydraulic aperture observed during unloading stages highlight the role of pressure solution. The increase in temperature of the injected fluid increases the recovery percentage of fracture aperture and permeability after unloading.

Beschreibung: Northeast Atlantic marine ecosystems such as the Bay of Biscay, Celtic Sea, English Channel, Subpolar Gyre region, Icelandic waters and North Sea as well as the Mediterranean Sea show concomitant ‘regime shift’-like changes around the mid-1990s, which involved all biota of the pelagial: phytoplankton, zooplankton, pelagic fish assemblages, demersal fish assemblages and top predators. These shifts were caused by complex ocean-atmosphere interactions initiating large-scale changes in the strength and direction of the current systems, that move water masses around the North Atlantic, and involved the North Atlantic Oscillation (NAO), the Atlantic Meridional Overturning Circulation (AMOC), and the subpolar gyre (SPG). The contractions and expansions of the SPG and fluctuations of the Atlantic Multidecadal Oscillation (AMO) play a key role in these complex processes. Small pelagic fish population trends were the sentinels of these changes in the mid-1990s in the ecosystems under investigation.

Beschreibung: Atlantic cod (Gadus morhua) is an important recreational and commercial fisheries target species in the Northern hemisphere. Release rates are high in the recreational fishery due to regulatory and voluntary catch-and-release practice. Although post-release mortality of cod is relatively low, there is potential for further reductions. The most effective way to reduce post-release mortality is to minimize the catch of sublegal fish or non-target species and to reduce hooking injuries by using more selective fishing methods. This study investigated the influence of the lure/bait type on: (1) size of fish, (2) catch and harvest, (3) proportion of bycatch, (4) hooking location, and (5) injury (bleeding) in the western Baltic Sea recreational cod fishery. Data were collected via random onboard sampling of 35 charter vessel angling trips (778 anglers) and during two supplementary studies in the western Baltic Sea. Overall, the median total length was significantly higher for cod caught on artificial lures (39 cm) than for cod caught on natural bait (28 cm), leading to a 43% higher proportion of sublegal (〈38 cm) cod for bait than for lure. Median catch-per-unit-efforts (number of captured cod per angling hour) did not differ significantly between lure and bait angling (both: 0.49 cod per hour), whereas the median harvest-per-unit-effort (number of captured cod ≥ minimum landing size (38 cm) per angling hour) was significantly higher for lure (0.24 cod ≥38 cm per hour) than for bait angling (0.06 cod ≥38 cm per hour). The incidence of deep hooking and severe bleeding was significantly higher for bait angling. Furthermore, bait angling significantly increased bycatch of other species dominated by whiting (Merlangius merlangus) and European flounder (Platichthys flesus). Cod anglers can reduce the catch of sublegal cod and non-target species and minimize hooking injuries of released fish by using lures instead of bait in the western Baltic Sea. Thus, voluntary terminal gear recommendations may be an effective tool for anglers and managers to increase selectivity in recreational cod fisheries.

Beschreibung: Highlights • Frequent sediment resuspension may have buffered D-Fe released from shelf sediments. • 228Ra was used to estimate trace element fluxes from the Chukchi shelf sediments. • The estimated sediment 228Ra flux ranks among the highest reported globally. • About 10–25% of the Chukchi shelf sediment Fe flux is exported to the Arctic Ocean. The Chukchi Sea is a primary site for shelf-ocean exchange in the Arctic region and modifies Pacific-sourced water masses as they transit via the Bering Strait into the Arctic Ocean. The aim of this study was to use radium and trace metal distributions to improve our understanding of biogeochemical cycles in the Bering and Chukchi Seas, and evaluate their potential response to future changes in the Arctic. We investigated the distributions of dissolved and total dissolvable trace metals (Cd, Fe, Ni, Cu, Zn, Mn, Co, and Pb) in the Bering and Chukchi Seas during spring. In addition, the long-lived radium isotopes (226Ra and 228Ra) were measured as tracers of benthic trace metal inputs. Trace metal concentrations, especially Fe and Mn, were highly elevated in Chukchi shelf waters compared with the open Arctic Ocean and Bering Strait. Trace metal, nutrient, and Ra patterns suggested that Fe, Mn, and Co concentrations were predominantly controlled by reductive benthic inputs, whereas the other trace metals were influenced by biological uptake and release processes. We propose that Fe, Mn, and Co in the Chukchi Sea are supplied from shelf sediments during winter overturning, and we combine the 228Ra fluxes with the distributions of Fe, Mn, and Co to provide a first estimate of their benthic fluxes in the region. The average benthic flux of 228Ra was 1.49 × 108 atoms m−2 d−1, which is among the highest rates reported globally. Estimated dissolved Fe (D-Fe) flux from the sediments was 2.5 μmol m−2 d−1, whereas D-Mn and D-Co fluxes were 8.0 μmol m−2 d−1 and 0.2 μmol m−2 d−1, respectively. The off-shelf transport of D-Fe to the Arctic Ocean is estimated to be about 10–25% of the benthic Fe flux, with the remainder retained on the shelf due to scavenging and/or phytoplankton uptake. Our results highlight the importance of the Chukchi Sea as a major source of the micro-nutrients to the Arctic Ocean, thereby supporting primary production. Long-term changes in factors that affect cross-shelf mixing, such as the observed reduction in ice cover, may therefore enhance shelf nutrient inputs and primary productivity in the Arctic.

Beschreibung: Proglacial streams deliver melt water and chemical weathering products, including nutrients and radiogenic isotopes, from continental ice sheets to the ocean. Weathering products are also delivered to the ocean in non-glacial streams that form following ice sheet retreat and are disconnected from ice sheet meltwater by hydrologic divides. If weathering reactions differ in non-glacial and proglacial stream catchments, the streams could deliver different types and magnitudes of solutes to the ocean, depending on relative discharge volumes. Unlike proglacial streams, however, little is known of non-glacial stream solute compositions or discharge. Here we show specific discharges are similar from a proglacial stream draining the Greenland Ice Sheet (GrIS) with several streams disconnected from the ice sheet. We also evaluate weathering reactions across a 170-km transect in western Greenland that contains one proglacial stream draining the GrIS, and two coastal (ice distal) and three inland (ice proximal) areas with non-glacial streams. Non-glacial streams exhibit solute compositions and offsets between dissolved and bedload Sr isotope ratios that indicate weathering increases toward the coast with exposure age and precipitation. Major element mass balance calculations show weathering reactions shift from predominately carbonic acid weathering of carbonate minerals inland near the ice sheet to predominately sulfuric acid weathering of carbonate minerals near the coast. Strontium concentrations and isotopic ratios of the proglacial stream reflect mixing of at least two subglacial sources and minor in-stream weathering that consumes CO2. About 5 times less CO2 is consumed per liter in the proglacial than inland non-glacial streams; however, arid conditions inland suggest limited discharge from the ungauged inland streams leads to less total CO2 weathering than proglacial stream. One coastal area consumes less CO2 per liter than the proglacial stream and another coastal area exhibits net CO2 production. These results indicate estimates for glacial foreland solute fluxes and CO2 weathering consumption and production should include estimates from both non-glacial and proglacial streams. Understanding weathering fluxes from these two types of streams will be important for evaluations of past ice sheet retreat and predictions of future solute and CO2 fluxes associated with continued ice sheet retreat.

Beschreibung: The Earth’s ocean floor deforms continuously under the influence of plate tectonic processes. In recent years, the development of deep-sea instruments using acoustic direct-path ranging allows observations of ocean floor deformation with unprecedented spatial and temporal resolution. Due to rapid technological progress, acoustic ranging emerged as a central research field to monitor seafloor deformation. Here we review recent developments and the progress of direct-path ranging applications. We discuss the methodology and examine the effects of the oceanographic environment on the measurement precision. Comparing the resolution of previous deployments, we find that the baseline uncertainty increases linearly with baseline length, at least for distances up to 3 km, but with different linear relations for each deployment. Measurements of displacement at millimeter-level precision across normal, thrust or strike-slip faults are discussed to evaluate the influence of dedicated network designs appropriate for the discrete fault geometries. Furthermore, tectonically quiet areas, such as flanks of coastal or ocean island volcanoes and passive continental margins pose substantial hazards that often lack in-situ monitoring and are therefore a significant target for the application of seafloor geodetic techniques.

Beschreibung: The role of accessory minerals in the incongruent release of Hf and Pb during continental weathering and its implications for the generation of distinct seawater isotope compositions is subject of debate. While it has been suggested that radiogenic Hf and Pb isotope signatures released during the dissolution of rocks are controlled by the relative abundances of minerals with distinct isotope compositions and differences in their resistance to dissolution there has not been a comprehensive experimental investigation of these processes to date. We carried out systematic sequential leaching experiments on fresh and partly weathered granitic rock samples as well as separated zircons from the Central Aar Granite in Switzerland. Combined with major and rare earth element concentrations our new quantitative experimental data reveal systematic preferential release of radiogenic Nd, Hf and Pb isotopes primarily controlled by dissolution characteristics of the host rock's easily dissolvable accessory and major minerals, in particular apatite and sphene, during weak chemical weathering. Moreover, Pb isotope signatures of incipient weathering conditions, contrary to expectations, indicate initial congruent release of Pb from freshly exposed mineral surfaces that becomes subsequently incongruent. During more advanced chemical weathering stages, as well as enhanced physical weathering conditions, the dissolution of major minerals (i.e. feldspars) becomes dominant for Nd and Pb isotope signatures, whereas Hf isotopes are still dominated by contributions from highly radiogenic accessories. Additional leaching experiments of zircon separates were performed to test the specific role of zircons for Hf isotope compositions of riverine runoff. It is demonstrated that zircon is more efficiently dissolved when physical weathering is enhanced. This increased Hf release originating from partial dissolution of zircons, however, is quantitatively not sufficient to explain less radiogenic Hf isotope signatures in seawater during episodes of enhanced mechanical erosion alone. Moreover, the observed addition of Hf from the more congruent dissolution of the zircon-free fractions of the parent rock due to enhanced physical weathering indicate that these minerals also play an important role in controlling Hf isotope signatures released under deglacial conditions.

Beschreibung: The Manihiki Plateau, a Large Igneous Province (LIP) in the western Pacific, has been proposed to be emplaced as part of the “Greater Ontong Java Event” during the early Cretaceous. Shortly after its formation, the Manihiki Plateau fragmented into multiple sub-provinces. Plate tectonic reconstructions ignore this fragmentation, treating the Manihiki Plateau as a single crustal block. By analyzing two seismic refraction/wide-angle reflection profiles crossing the two largest sub-provinces of the Manihiki Plateau, we provide new insight into their deep crustal structure and magmatic evolution. Our data indicate that the High Plateau and the Western Plateaus were emplaced as a single unit during an initial phase of massive magmatic activity, but later magmatic stages altered the individual sub-provinces considerably. The High Plateau has a crustal thickness of 20 km and its P-wave velocity distribution is comparable to previously surveyed oceanic LIPs. Strong secondary magmatic phases are visible by eruptive centers and former magmatic pathways in the middle and lower crust. The Western Plateaus, which have a crustal thickness decreasing gradually from 17.3 km (East) to 9.2 km (West), experienced smaller amounts of magmatism mainly along fault zones and on local seamounts. Therefore, we propose a distinct development of the two main sub-provinces of the Manihiki Plateau after their initial joint emplacement. The High Plateau experienced voluminous multi-phase magmatic accretion and extrusion, whereas the thinner Western Plateaus exhibit only relatively minor magmatic growth. Such a large difference in the evolution process has not been reported from any other oceanic LIP so far.

Beschreibung: A central aspect of coastal biogeochemistry is to determine how nutrients, lithogenic- and organic matter are distributed and transformed within coastal and estuarine environments. Analyses of the spatio-temporal changes of total suspended matter (TSM) concentration indicate strong and variable linkages between intertidal fringes and pelagic regions. In particular, knowledge about the organic fraction of TSM provides insight to how biogenic and lithogenic particulate matter are distributed in suspension. In our study we take advantage of a set of over 3000 in situ Loss on Ignition (LoI) data from the Southern North Sea that represent fractions of particulate organic matter (POM) relative to TSM (LoI $\equiv$ POM:TSM). We introduce a parameterization (POM-TSM model) that distinguishes between two POM fractions incorporated in TSM. One fraction is described in association with mineral particles. The other represents a seasonally varying fresh pool of POM. The performance of the POM-TSM model is tested against data derived from MERIS/ENVISAT-TSM products of the German Bight. Our analysis of remote sensing data exhibits specific qualitative features of TSM that can be attributed to distinct coastal zones. Most interestingly, a transition zone between the Wadden Sea and seasonally stratified regions of the Southern North Sea is identified where mineral associated POM appears in concentrations comparable to those of freshly produced POM. We will discuss how this transition is indicative for a zone of effective particle interaction and sedimentation.The dimension of this transition zone varies between seasons and with location. Our proposed POM-TSM model is generic and can be calibrated against in situ data of other coastal regions.

Beschreibung: Highlights: • Clay dehydration water expelled from buried sediments drives mud volcanism. • Rise of fluids mediated by crustal-scale strike-slip faults cross-cutting wedge. • On active accretionary wedge, petroleum accumulations were dismantled in Neogene. • 4He enrichment and δ13C-CH4 ~−50‰ in fluids reflect an open hydrocarbon system. • Petroleum pools remain on shallow margin. Microbial gas vented out of active wedge. Abstract: A geochemical study of the composition of hydrocarbon gases and helium isotopes (3He/4He) in fluids from Mud Volcanoes (MVs) located on and out of the active accretionary wedge of the Gulf of Cadiz (GoC) provides information on fluid sources and migrations in deeply buried sediments. The GoC is a tectonically active segment of the Africa-Iberia plate boundary occluded beneath the thick sediments of an accretionary wedge dissected by crustal-scale strike-slip faults. Initially built during the Miocene Gibraltar Arc subduction, the wedge has since developed toward the W-NW in an oblique convergent setting. Interstitial water expelled from clays undergoing diagenesis in buried sediments drives mud volcanism on the wedge, with MVs located along strike-slip faults mediating fluid ascent. The large excess of radiogenic helium (4He) in all GoC fluids agrees with a clay mineral dehydration source of water. Hydrocarbon gases from all deepwater MVs bear methane having similar stable carbon isotope compositions of ~−50‰VPDB whether fluids are highly enriched in methane relative to heavier homologues (C2+) or not (Methane / (Ethane + Propane) ~10 to 10,000). We suggest that methane with −50‰VPDB was largely diffused out of early generating source rocks, and became dissolved in the water expelled by the buried sediments. Consistently, low 3He/4He ratios suggest an open hydrocarbon system: Petroleum accumulations and 3He dissolved in the original sedimentary pore water have mostly escaped into the water column during the major Late Neogene compressional events. At present, some MVs vent CH4-rich fluids from dewatering sediments, while other structures located on active thrusts additionally vent C2+-rich gases generated by active Cretaceous source intervals. By contrast, evaporitic seals preserved petroleum accumulations on the shallow Moroccan Margin, while the westernmost MVs located out of the accretionary wedge vent microbial gas.

Beschreibung: Diurnal vertical migration (DVM) is a widespread phenomenon in the upper ocean, but it remains unclear to what degree it also involves passively transported micro- and meso-zooplankton. These organisms are difficult to monitor by in situ sensing and observations from discrete samples are often inconclusive. Prime examples of such ambiguity are planktonic foraminifera, where contradictory evidence for DVM continues to cast doubt on the stability of species vertical habitats, which introduces uncertainties in geochemical proxy interpretation. To provide a robust answer, we carried out highly replicated randomised sampling with 41 vertically resolved plankton net hauls taken within 26 hours in a confined area of 400 km2 in the tropical North Atlantic, where DVM in larger plankton occurs. Manual enumeration of planktonic foraminifera cell density consistently reveals the highest total cell concentrations in the surface mixed layer (top 50 m) and analysis of cell density in seven individual species representing different shell sizes, life strategies and presumed depth habitats reveals consistent vertical habitats not changing over the 26 hours sampling period. These observations robustly reject the existence of DVM in planktonic foraminifera in a setting where DVM occurs in other organisms.

Beschreibung: Abstract ETHNOPHARMACOLOGICAL RELEVANCE: The oleoresin of Brazilian Copaifera reticulata is a traditional remedy used for the treatment of skin and urinary tract infections, respiratory diseases, rheumatism, ulcer and tumours; thus, playing an important role in the primary health care of the indigenous population. AIM: As most previous pharmacological tests used the crude oleoresin and only a few studies so far dealt with enriched fractions or pure chemically defined compounds, the aim of this study was to systematically evaluate the antimicrobial and cytotoxic properties of the Copaifera reticulata oleoresin and to assign traditional uses to specific secondary metabolites. MATERIALS AND METHODS: The oleoresin, as well as its neutral and acidic fractions were tested for their activity against six cancer cell lines, two clinically relevant bacterial strains, and two dermatophytes. Both fractions were analysed by GC-MS and UHPLC-ELSD, respectively. The antibacterial acidic phase was further fractionated by preparative chromatography to purify and characterize the compounds responsible for the observed pharmacological effect. RESULTS: Whereas no cytotoxic activity was detected, the crude oleoresin and its acidic fraction showed antibacterial activity against gram-positive bacteria Enterococcus faecium (IC50 values 4.2 and 4.8 µg/mL, respectively) and methicillin-resistant Staphylococcus aureus (MRSA, IC50 values 5.3 and 7.2 µg/mL, respectively). Purification of the acidic fraction of the C. reticulata oleoresin yielded two dicarboxylic diterpene acids and the four main diterpene acids, comprising three different diterpene scaffolds. Interestingly, the activity was not restricted to a particular diterpene-type but rather depended on the compounds' lipophilicity, with the most active constituent showing IC50 values of 1.6 (E. faecium) and 2.5 µg/mL (MRSA), respectively. Furthermore, ent-polyalthic acid, the major diterpenoid, was significantly active against dermatophytes with IC50 values of 6.8 µg/mL (Trichophyton rubrum) and 4.3 µg/mL against (T. mentagrophytes). CONCLUSION: The present study proved the antimicrobial effects of the C. reticulata oleoresin and its diterpenoid constituents, confirming its wide use in folk medicine for the treatment of skin and urinary tract infections. The inhibitory activity of copaiba diterpenoids against dermatophytic fungi as well as the gram-positive bacteria E. faecium and MRSA is being reported for the first time, providing potential lead structures for the treatment of these clinically relevant bacterial strains.

Beschreibung: 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.

Beschreibung: Highlights • First deep water Nd and Pb isotope records from the glacial–deglacial Nordic Seas. • Deglacial changed by up to six units from unradiogenic LGM background. • Glacial–deglacial Nd and Pb isotope changes controlled by local weathering input. • Pb isotopes suggest synchronous postglacial weathering fluxes around the North Atlantic. • Holocene Nd isotope evolution dominated by re-invigorated water mass mixing. Abstract Neodymium (Nd) isotopes are a powerful proxy tool for reconstructing past changes in water mass mixing, but reliable application of this proxy requires constraints on past changes of source water compositions. A key region of the global deep water circulation system are the Nordic Seas, which provide dense waters fundamental for the formation of North Atlantic Deep Water (NADW). Yet, the Nd isotope evolution of past deep waters in the Nordic Seas is so far poorly constrained. Here we present the first reconstructions of seawater Nd isotope compositions extracted from marine sediments at two locations in the central and northern Nordic Seas covering the period from the last glacial to the present. Further insights into past changes in sediment provenance, weathering inputs and water mass mixing are provided by complementary seawater and detrital strontium (Sr) and lead (Pb) isotope compositions. Our new data reveal that changes in source and magnitude of weathering inputs from the Scandinavian and Svalbard–Barents Ice Sheets (SIS and SBIS, respectively) controlled the Nd and Pb isotope composition of the Nordic Seas' deep waters during the last glacial period. During the Last Glacial Maximum (LGM), deep waters showed distinctly unradiogenic Nd and radiogenic Pb isotope signatures most likely driven by weathering inputs of the SBIS. In contrast, the deglaciation was characterized by enhanced SBIS ice dynamics and/or meltwater release delivering sediments from the distal Eurasian shelves to the Norwegian Sea. Pulses of volcanogenic sediment supply changed the deep water Nd isotope composition during Heinrich Stadials 1, 2 and the Bølling period. As such, the glacial–deglacial Nd and Pb isotope evolution was markedly different in the Nordic Seas, the North Atlantic and the Arctic Oceans, respectively. During the Holocene, Pb isotopes indicate synchronized weathering fluxes around the North Atlantic, whereas the influence of local weathering input on the Nd isotope evolution of the deep Nordic Seas ceased. Instead, the Holocene Nd isotope signal has been driven by the strength of the advection/convection of water masses in the study area. These new constraints on changes in the Nordic Seas provide important endmember information for Nd isotope based reconstructions of NADW export downstream in the Atlantic Ocean.

Beschreibung: 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.