ALBERT

Description: Experiments investigating Ca isotopic fractionation during gypsum precipitation were undertaken in order to elucidate the mechanisms and conditions that govern isotopic fractionation during mineral precipitation. Both stirred and unstirred free drift gypsum precipitation experiments were conducted at constant initial ionic strength (0.6 M) and variable initial saturation states (4.8–1.5) and Ca2+:SO42− ratios (3 and 0.33). Experimental durations varied between 0.5 and 190 h, while temperature (25.9–24.0 °C), pH (5.8–5.4) and ionic strength (0.6–0.5) were relatively constant. In all experiments, 20–80% of the initial dissolved Ca reservoir was precipitated. Isotopically light Ca preferentially partitioned into the precipitated gypsum; the effective isotopic fractionation factor (Δ44/40Cas–f = δ44/40Casolid − δ44/40Cafluid) of the experimental gypsum ranged from −2.25‰ to −0.82‰. The log weight-averaged, surface area normalized precipitation rates correlated with saturation state and varied between 4.6 and 2.0 μmol/m2/h. The crystal size and aspect ratios, determined by SEM images, BET surface area, and particle size measurements, co-varied with precipitation rate, such that fast growth produced small (10–20 μm), tabular crystals and slow growth produced larger (〉1000 μm), needle shaped crystals. Mass balance derived δ44Cas and Δ44Cas–f, calculated using the initial fluid δ44Ca and the mass fraction of Ca removed during precipitation (fCa) as constraints, suggest that the precipitate was not always sampled homogeneously due to the need to preserve the sample for SEM, surface area, and particle size analyses. The fractionation factor (αs–f), derived from Rayleigh model fits to the fluid and calculated bulk solid, ranged from 0.9985 to 0.9988 in stirred experiments and 0.9987 to 0.9992 in unstirred experiments. The αs–f demonstrated no clear dependence on either precipitation rate or initial saturation state in stirred reactors, but exhibited a positive dependence on rate in unstirred experiments. The differences in αs–f between stirred and unstirred reactors, as well as a general correlation between αs–f and crystal morphology, led us to hypothesize that growth on different crystal faces controls the isotopic composition of gypsum. We also explore the idea that speciation in solution explains the difference between experiments in which the only major difference was the Ca2+ to SO42− ratio in solution. The importance of understanding the environmental controls on the fractionation factor during mineral precipitation is highlighted in this study. The fractionation factor of gypsum precipitation near chemical equilibrium was found to be ∼0.9995, rather than 1, indicating that even at near equilibrium conditions, the δ44Ca of minerals are not likely to record the δ44Ca of the solution directly. However, the measurable isotopic fractionation associated with gypsum formation does suggest that a gypsum-based proxy may be useful in constraining Ca cycling in marginal environments over geologic time scales. Model examples are provided that demonstrate how such a proxy would operate.

Description: Highlights • An individual-based model was developed and coupled to a pore-network model. • The bacterial distribution patterns were geostatistically analyzed. • The effects from bacterial chemotactic properties on bacterial distribution patterns were examined. • The additional influences from structural heterogeneities were examined. Abstract Spatial distribution of soil microorganisms is relevant for the functioning and performance of many ecosystem processes such as nutrient cycling or biodegradation of organic matters and contaminants. Beside the multitude of abiotic environmental factors controlling the distribution of microorganisms in soil systems, many microbial species exhibit chemotactic behavior by directing their movement along concentration gradients of nutrients or of chemoattractants produced by cells of their own kind. This chemotactic ability has been shown to promote the formation of complex distribution patterns even in the absence of environmental heterogeneities. Microbial population patterns in heterogeneous soil systems might be, hence, the result of the interplay between the heterogeneous environmental conditions and the microorganisms' intrinsic pattern formation capabilities. In this modeling study, we combined an individual-based modeling approach with a reactive pore-network model to investigate the formation of bacterial patterns in homogeneous and heterogeneous porous media. We investigated the influence of different bacterial chemotactic sensitivities (toward both substrate and bacteria) on bacterial distribution patterns. The emerging population patterns were classified with the support of a geostatistical approach, and the required conditions for the formation of any specific pattern were analyzed. Results showed that the chemotactic behavior of the bacteria leads to non-trivial population patterns even in the absence of environmental heterogeneities. The presence of structural pore scale heterogeneities had also an impact on bacterial distributions. For a range of chemotactic sensitivities, microorganisms tend to migrate preferably from larger pores toward smaller pores and the resulting distribution patterns thus resembled the heterogeneity of the pore space. The results clearly indicated that in a porous medium like soil the distribution of bacteria may not only be related to the external constraints but also to the chemotactic behavior of the bacterial cells.

Description: Highlights • Fatty acids preserved in an Oligocene whale bone were analysed. • The fatty acid content of the fossil was in the permil range vs. a recent whale vertebra. • Ca. 80% of the n-C16 and n-C18 alkyl moieties were extractable, ca. 20% being bound to kerogen. • Endogenous fatty acids were largely of microbial origin (sulfate reducers, actinobacteria). Abstract The taphonomic and diagenetic processes by which organic substances are preserved in animal remains are not completely known and the originality of putative metazoan biomolecules in fossil samples is a matter of scientific discussion. Here we report on biomarker information preserved in a fossil whale bone from an Oligocene phosphatic limestone (El Cien Fm., Mexico), with a focus on fatty acyl compounds. Extracts were quantitatively analysed using gas chromatography–mass spectrometry (GC–MS) and, to identify macromolecular-linked remains, demineralised extraction residues were subjected to catalytic hydropyrolysis (HyPy). To better recognise potential authentic (i.e. animal-derived) lipids, the data from the ancient bone were compared with those obtained from (i) the adjacent host sediment of the fossil and (ii) a recent whale (Phocoena phocoena) vertebra. In addition, the spatial distribution of organic and inorganic species was observed at the μm level by imaging MS (time-of-flight-secondary ion mass spectrometry, ToF-SIMS). Our results revealed a rather even distribution of hydrocarbon-, O- and N-containing ions in the trabecular network of the ancient bone. A different, more patchy arrangement of organic compounds was evident in the former marrow cavities that were partly cemented by clotted micrites of putative microbial origin. The concentration of fatty acids (FAs) in the ancient bone was in the permil range of the amount extracted from the recent whale vertebra. Endogenous compounds, including monoenoic n-C16 and n-C18 as well as branched FAs, were identified in the fossil bone by comparison with the host sediment. Ca. 80% of the prevalent n-C16 and n-C18 moieties in the ancient bone were extractable as FAs, whereas ca. 20% were covalently bound in the non-saponifiable kerogen fraction. Ample pyrite precipitates, distinctive 10-methyl branched FAs and microbial microborings (“tunneling”) indicate that sulfate reducers and collagen-degrading actinomycetes were central players in the microbial decomposition of the bone. Similarities with reported microbial FA patterns suggest that the FAs in the fossil bone were largely contributed by these microbial “last eaters”. The results highlight some of the degradation and preservation mechanisms during marine FA diagenesis in the “natural laboratory” of bones, and therefore the processes that lead to either degradation, preservation, or introduction of these widespread biomolecules in the fossils of ancient marine animals.

Description: A simple earth system model is developed to simulate global carbon and phosphorus cycling over the late Quaternary. It is focused on the geological cycling of C and P via continental weathering, volcanic and metamorphic degassing, hydrothermal processes and burial at the seabed. A simple ocean model is embedded in this geological model where the global ocean is represented by surface water, thermocline and deep water boxes. Concentrations of dissolved phosphorus, dissolved inorganic carbon, and total alkalinity are calculated for each box. The partial pressure of CO2 in the atmosphere (pCO(2A)) is determined by exchange processes with the surface ocean and the continents. It serves as key prognostic model variable and is assumed to govern surface temperatures and global sea-level. The model is formulated as autonomous system, in which the governing equations have no explicit time-dependence. For certain parameter values, the model does not converge towards a steady-state but develops stable self-sustained oscillations. These free oscillations feature pCO(2A) minima and maxima consistent with the ice-core record when vertical mixing in the ocean is allowed to vary in response to pCO(2A)-controlled temperature change. A stable 100-kyr cycle with a rapid transition from glacial to interglacial conditions is obtained when additional non-linear equations are applied to calculate deep ocean mixing, iron fertilization and the depth of organic matter degradation as function of pCO(2A)-controlled surface temperature. The delta C-13 value of carbon in the ocean/atmosphere system calculated in these model runs is consistent with the benthic delta C-13 record. However, the simulated C-13 depletion in the glacial ocean is not driven by the decline in terrestrial carbon stocks but by sea-level change controlling the rates of organic carbon burial and weathering at continental margins. The pCO(2A)-and delta C-13 oscillations develop without any form of external Milankovitch forcing. They are induced and maintained by sea-level change generating persistent imbalances in the marine carbon and phosphorus budgets. Stable oscillations are also obtained when sea-level change is allowed to lag temperature with a realistic time scale for ice-sheet adjustment

Description: Highlights: • Feeding 0.1% Macrogard® for 25 days increased CRP and complement responses in carp. • β-glucan affected gene expression in the liver, head kidney and mid-gut tissues. • Gene expression was more affected by LPS and poly(I:C) in the β-glucan fed fish. • Carp acute phase response to PAMPs injection was stimulated by β-glucan. Abstract: The effect of β-glucan as a feed additive on the serum and gene profile of C-reactive protein (CRP) and complement acute phase responses was ascertained in common carp Cyprinus carpio. In addition effects of subsequent intraperitoneal injections of pathogen-associated molecular patterns (PAMPs), i.e. LPS or poly(I:C), to mimic bacterial or viral infection respectively, were studied. Carp were first orally fed with β-glucan (MacroGard®) with a daily β-glucan intake of 6 mg per kg body weight or with control food for 25 days and then injected with PBS containing either LPS (4 mg/kg) or poly(I:C) (5 mg/kg) or PBS alone. Fish were sampled during the 25 days of the feeding period and up to 7 days post-PAMPs injections for serum and liver, head kidney and mid-gut tissues. Oral administration of β-glucan for 25 days significantly increased serum CRP levels and alternative complement activity (ACP). In addition, the subsequent LPS and poly(I:C) challenges significantly affected CRP and complement related gene expression profiles (crp1, crp2, c1r/s, bf/c2, c3 and masp2), with the greatest effects observed in the β-glucan fed fish. However, in fish fed β-glucan the PAMPs injections had less effects on CRP levels and complement activity in the serum than in control fed fish, suggesting that the 25 days of β-glucan immunostimulation was sufficient enough to reduce the effects of LPS and poly(I:C) injections. Results suggest that MacroGard® stimulated CRP and complement responses to PAMPs immunological challenges in common carp thus highlighting the beneficial β-glucan immunostimulant properties.

Description: Biological activity introduces variability in element incorporation during calcification and thereby decreases the precision and accuracy when using foraminifera as geochemical proxies in paleoceanography. This so-called 'vital effect' consists of organismal and environmental components. Whereas organismal effects include uptake of ions from seawater and subsequent processing upon calcification, environmental effects include migration- and seasonality-induced differences. Triggering asexual reproduction and culturing juveniles of the benthic foraminifer Ammonia tepida under constant, controlled conditions allow environmental and genetic variability to be removed and the effect of cell-physiological controls on element incorporation to be quantified. Three groups of clones were cultured under constant conditions while determining their growth rates, size-normalized weights and single-chamber Mg/Ca and Sr/Ca using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Results show no detectable ontogenetic control on the incorporation of these elements in the species studied here. Despite constant culturing conditions, Mg/Ca varies by a factor of similar to 4 within an individual foraminifer while intra-individual Sr/Ca varies by only a factor of 1.6. Differences between clone groups were similar to the intra-clone group variability in element composition, suggesting that any genetic differences between the clone-groups studied here do not affect trace element partitioning. Instead, variability in Mg/Ca appears to be inherent to the process of bio-calcification itself. The variability in Mg/Ca between chambers shows that measurements of at least 6 different chambers are required to determine the mean Mg/Ca value for a cultured foraminiferal test with a precision of 〈= 10%

Description: We examined metal (Al, V. Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb) and particulate organic carbon (OC) concentrations of the marine vertical export flux at the DYFAMED time-series station in the Northwestern Mediterranean Sea. We present here the first data set of natural and anthropogenic metals from sediment trap moorings deployed at 1000 m-depth between 2003 and 2007 at the DYFAMED site. A highly significant correlation was observed between most metal concentrations, whatever the nature and emission source of the metal. Cu, Zn and Cd exhibit different behaviors, presumably due to their high solubility and complexation with organic ligands. The observed difference of atmospheric and marine fluxes in terms of temporal variability and elemental concentration suggests that dense water convection and primary production and not atmospheric deposition control the marine vertical export flux. This argument is strengthened by the fact that significant Saharan dust events did not result in concomitant marine vertical export fluxes nor did they generate significant changes in metal concentrations of trapped particles

Description: Highlights: • Regional initiatives have recently developed in areas beyond national jurisdiction. • They advance the governance of these areas while the global discussions are on-going. • They however face many challenges, which should be tackled. • Global discussions and regional actions are two interconnected processes. Abstract: The development of regional initiatives for the protection of the environment is a cornerstone of international environmental policies. With regard to marine and coastal issues, this regionalisation has mainly been taking place through regional seas programmes and Regional Fisheries Management Organisations. Some regional initiatives and organisations have progressively extended their activities to areas beyond national jurisdiction. This paper aims at analysing these recent developments, highlighting their interests and challenges, and proposing options to strengthen the efficiency of regional actions in these areas. It also highlights the need to consider the global discussions on a possible new global agreement and the development of regional actions as two interconnected processes.

Description: The ocean regulates the global climate, provides humans with natural resources such as food, materials, important substances, and energy, and is essential for international trade and recreational and cultural activities. Together with human development and economic growth, free access to, and availability of, ocean resources and services have exerted strong pressure on marine systems, ranging from overfishing, increasing resource extraction, and alteration of coastal zones to various types of thoughtless pollution. International cooperation and effective governance are required to protect the marine environment and promote the sustainable use of marine resources in such a way that due account can be taken of the environmental values of current generations and the needs of future generations. The high seas deserve particular attention since they suffer from a number of regulatory shortcomings due to the basic structures set out under international law. Against this backdrop, developing and agreeing on a focussed Sustainable Development Goal (SDG) specifically for the Ocean and Coasts could prove to be an essential element to provide guidance and a framework for regional implementation agreements.

Description: Highlights: • Belt Sea cod, plaice and flounder differentiate in their specific egg densities. • Ontogenetic egg density increase in stage IV cod eggs elevates modeled egg mortality. • Drift model indicates retention in western Baltic in cod and flatfish yolk sac larvae. • No eastward transport to Arkona Sea or Bornholm Sea until end of yolk sac stage. • Ambiguity in flounder egg density could reflect more complex population structure. Abstract: Vertical distribution is an important feature of pelagic fish eggs and yolk sac larvae impacting their survival and dispersal, especially in heterogeneous and highly variable estuarine environments like the Baltic Sea. Egg densities determining the vertical distribution pattern were experimentally ascertained for cod (Gadus morhua), plaice (Pleuronectes platessa) and flounder (Platichthys flesus) from the western Baltic Sea. Plaice eggs floated at lower mean (±standard deviation) density range (1.0136 ± 0.0007 g cm−3) compared to cod (1.0146 ± 0.0009 g cm−3) and flounder eggs (1.0160 ± 0.0015 g cm−3), which floated on the highest density level. In flounder egg diameter was significantly related to egg density and in cod a weak correlation could be found between egg dry weight and density. All other relationships between female size, egg size, egg dry weight and egg density were not significant for any of the species. Available egg density data for Baltic Sea cod, plaice and flounder are summarized considering ICES subdivisions and stock management units. A hydrodynamic drift modeling approach was applied releasing drifters in the Belt Sea continuously from December to May, covering the species’ spawning seasons. The model implemented experimentally derived egg density ranges and included ontogenetic egg density modifications for cod eggs, increasing egg density from a late egg development stage to first hatch. A drifter was removed from the model, i.e. considered dead, when its initially prescribed density value exceeded the density range available at the temporally resolved geographical positions along the drift trajectories. Highest survival occurred during releases in April and May but no cohorts survived if they were drifted east into the central Arkona Basin or the central Baltic Sea, irrespective of whether a major Baltic Inflow (1992/1993) or a stagnation-year (1987/1988) was simulated. The dispersal characteristics of the surviving yolk sac larvae of all three species reflected retention within the Belt Sea or northwards transport through the Great Belt into the Kattegat and partly into the Skagerrak. There was no successful transport to more eastern Baltic areas past a hypothetical line from the island of Moen (Denmark) to Kap Arkona on Rügen Island (Germany).

Description: Highlights: • Strait processes trigger phytoplankton production and biomass in the Atlantic Inflow. • Strait processes may modify original phytoplankton succession in the Atlantic Inflow. • Model shows that nanoflag. may dominate during spring/autumn, picophytopl. in summer. • Strait processes lead in a constant supply of nutrients and biomass to Alboran Sea. Abstract: A physical-biological coupled model was used to estimate the effect of the physical processes at the Strait of Gibraltar over the biogeochemical features of the Atlantic Inflow (AI) towards the Mediterranean Sea. This work was focused on the seasonal variation of the biogeochemical patterns in the AI and the role of the Strait; including primary production and phytoplankton features. As the physical model is 1D (horizontal) and two-layer, different integration methods for the primary production in the Biogeochemical Fluxes Model (BFM) have been evaluated. An approach based on the integration of a production-irradiance function was the chosen method. Using this Plankton Functional Type model (BFM), a simplified phytoplankton seasonal cycle in the AI was simulated. Main results included a principal bloom in spring dominated by nanoflagellates, whereas minimum biomass (mostly picophytoplankton) was simulated during summer. Physical processes occurring in the Strait could trigger primary production and raise phytoplankton biomass (during spring and autumn), mainly due to two combined effects. First, in the Strait a strong interfacial mixing (causing nutrient supply to the upper layer) is produced, and, second, a shoaling of the surface Atlantic layer occurs eastward. Our results show that these phenomena caused an integrated production of 105 g C m− 2 year− 1 in the eastern side of the Strait, and would also modify the proportion of the different phytoplankton groups. Nanoflagellates were favored during spring/autumn while picophytoplankton is more abundant in summer. Finally, AI could represent a relevant source of nutrients and biomass to Alboran Sea, fertilizing the upper layer of this area with 4.95 megatons nitrate year− 1 (79.83 gigamol year− 1) and 0.44 megatons C year− 1. A main advantage of this coupled model is the capability of solving relevant high-resolution processes as the tidal forcing without expensive computing requirements, allowing to assess the effect of these phenomena on the biogeochemical patterns at longer time scales.

Description: To better understand Pleistocene climatic changes in the Arctic, integrated palaeoenvironmental and palaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologic age control are required, not least for correlation to extra-Arctic records. In this paper we discuss, from an Arctic perspective, methods and correlation tools that are commonly used to date Arctic Pleistocene marine and terrestrial events. We review the state of the art of Arctic geochronology, with focus on factors that affect the possibility and quality of dating, and support this overview by examples of application of modern dating methods to Arctic terrestrial and marine sequences. Event stratigraphy and numerical ages are important tools used in the Arctic to correlate fragmented terrestrial records and to establish regional stratigraphic schemes. Age control is commonly provided by radiocarbon, luminescence or cosmogenic exposure ages. Arctic Ocean deep-sea sediment successions can be correlated over large distances based on geochemical and physical property proxies for sediment composition, patterns in palaeomagnetic records and, increasingly, biostratigraphic data. Many of these proxies reveal cyclical patterns that provide a basis for astronomical tuning. Recent advances in dating technology, calibration and age modelling allow for measuring smaller quantities of material and to more precisely date previously undatable material (i.e. foraminifera for C-14, and single-grain luminescence). However, for much of the Pleistocene there are still limits to the resolution of most dating methods. Consequently improving the accuracy and precision (analytical and geological uncertainty) of dating methods through technological advances and better understanding of processes are important tasks for the future. Another challenge is to better integrate marine and terrestrial records, which could be aided by targeting continental shelf and lake records, exploring proxies that occur in both settings, and by creating joint research networks that promote collaboration between marine and terrestrial geologists and modellers.

Description: The Atlantis II Deep is one of the only locations on the modern seafloor where active formation of a brine pool-type stratiform ore deposit can be studied. The presence of the brine pool causes retention of the hydrothermally released metals within the brine covered area, resulting in the accumulation of 90 Mt of low-grade metalliferous sediment (2.06% Zn, 0.46% Cu, 41 g/t Ag, and 0.5 g/t Au; Guney et al., 1988). Almost all metals are derived from hydrothermal input, but some are also derived from seawater (e.g., Mo), pelagic phytoplankton (Ni) and detrital input (Cr). The hydrothermal fluid that is vented into the pool is rich in metals but relatively low in reduced sulfur compared to open ocean black smokers. Metals are deposited as sulfides from the cooling hydrothermal fluid but also by adsorption onto non-sulfidic “surface-active” particles (Si–Fe-OOH) in the brine pool. An unexpected increase in the Cu/Zn ratio of the sediments with distance from the vent source(s) may reflect pulses of higher-temperature venting and increased Cu fluxes to the brine pool, which are recorded as higher Cu/Zn ratios in the distal sediments or, alternatively, more efficient adsorption of Cu to Fe-OOH particles in the distal brine. During early diagenesis (a few thousand years) metals that are loosely bound to surface-active particles in the sediment apparently react with H2S to form sulfides. Proximal to the inferred vents, the ambient pore water is highly concentrated in trace metals such as Cd, Ag and Hg that are incorporated in diagenetic sulfides, including chalcopyrite and sphalerite. At greater distance from the vents, trace metals such as Mo, As, and Ga are taken up by framboidal pyrite. High concentrations of Au (up to 3 ppm) are found in both proximal and distal metalliferous sediments, indicating that both primary deposition with sulfides and adsorption by diagenetic pyrite are important depositional processes. Some of the inferred pathways for metal precipitation in the Atlantis II Deep sediments, especially adsorption onto surface-active particles and subsequent incorporation in sulfides during diagenesis, may have been important unrecognized processes for metal accumulation in ancient stratiform ore deposits thought to have formed in brine pools.

Description: Here we present trace element and Sr-Nd-Hf-Pb (double spike) isotopic data covering the entire igneous section of oceanic crust drilled at Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) Site 1256 on the Cocos Plate. The penetrated interval extends from the upper lavas through the sheeted dike complex to the gabbroic plutonic rocks, formed during superfast spreading at the mid-Miocene equatorial East Pacific Rise. The data are used to characterize the effects of chemical alteration, resulting from convection of seawater and hydrothermal fluids, on the trace element and isotopic composition of oceanic crust. Compared to normal mid-ocean-ridge basalt, the igneous basement of Site 1256 (Holes 1256C/D) is isotopically slightly enriched but shows only narrow downhole variations in Nd-Hf-Pb isotope ratios: 143Nd/144Nd = 0.513089 ± 0.000028 (2σ), 176Hf/177Hf = 0.283194 ± 0.000033 (2σ), 206Pb/204Pb = 18.61 ± 0.11 (2σ), 207Pb/204Pb = 15.521 ± 0.014 (2σ), 208Pb/204Pb = 38.24 ± 0.15 (2σ). We believe that this minor variability is mainly of primary (magmatic) origin. The Sr isotopic composition shows considerably larger variation and, as expected, serves as sensitive tracer of seawater influence, which is particularly pronounced in the lava-dike transition zone and the sheeted dikes. The seawater influence is most prominent in a highly metal sulfide-enriched breccia layer encountered in the transition zone with 87Sr/86Sr of ~ 0.706, indicating a maximum water-rock mixing ratio of ~ 12. However, compared to the igneous section drilled at Site 504 (Hole 504B), which formed at intermediate, i.e., slower spreading rates at the Galápagos Spreading Center and hosting a much thicker sulfide-rich stockwork zone, the average intensity of water-rock interaction is lower. This is expressed by lesser mobility of base metals, narrower variability of alteration-sensitive incompatible elements, and less radiogenic Sr isotopic compositions on average at Site 1256. The amount of metal sulfide precipitation seems to be positively correlated with the degree of hydrothermal overprint. The less intense alteration of the Site 1256 transition zone, compared to Site 504, most likely reflects the higher rate of spreading, eventually resulting in a shorter period of time of continuous exposure to hydrothermal convection at the ridge crest. The observed seafloor alteration, leading to modified radiogenic parent/daughter ratios in the Site 1256 rocks, is ultimately not sufficient to develop time-integrative high 206Pb/204Pb and moderate 87Sr/86Sr ratios, as being characteristic of the HIMU (high μ = high 238U/204Pb) mantle signature proposed to originate from hydrothermally altered, subducted oceanic crust. Therefore, additional modification during the subduction process must be taken into account.

Description: Carbonate chimney-like deposits up to 60 m high are scattered or arranged in rows at the shores of a desiccating hypersaline and alkaline lake from a continental rift setting (Lake Abhé, Afar Rift, Djibouti). The chimneys formed sub-aqueously in the lake water body at a higher water level than observed today. Alternating calcite and low-Mg calcite + silica concentric layers compose the chimney structures. Mineralogical and geochemical investigations of the chimneys, lake water, and hot spring (hydrothermal) fluids suggest that the chimneys are a result of rapid carbonate precipitation during the mixing of hydrothermal fluids with lake water. In contrast to the hot spring fluid, lake water is enriched in HREE and possesses a pronounced positive Ce anomaly, features that are preserved in the carbonate chimney layers. Mixing calculations based on Sr-isotope and concentration data indicate a hydrothermal fluid contribution of ~ 45% in the chimney interior, which decreases to ~ 4% in the external chimney layer. Sr in the hydrothermal fluids is predominantly leached from the underlying volcanic rocks, whereas the lake's Sr budget is dominated by riverine input. Considering the fluid mixing ratios calculated by Sr-data, the measured C and O isotope compositions indicate that chimney carbonates precipitated at temperatures between 14 °C (internal part) and 22 °C (external part) with δ13C-carbonate mainly controlled by isotope equilibrium exchange of lake water with atmospheric CO2. The low-Mg calcite layers, including the outermost layer, have enhanced signals of lake water inheritance based on elevated concentrations of immobile elements, ΣREE, and Sr and Ca isotope compositions. Ca-isotope data reveal that internal chimney layers formed by non-equilibrium calcite precipitation with a predominantly hydrothermal Ca source. The external low-Mg calcite layer received Ca contributions from both hydrothermal fluid and lake water, with the latter being the dominant Ca source. Highly positive δ44/40Ca of lake water likely reflects non-equilibrium Ca-carbonate precipitation during lake water evaporation with resulting 44Ca enrichment of residual lake water. The strong degree of 44Ca enrichment may point towards multiple lake drying and Ca-reservoir depletion events. Coupled C–O–Ca-isotope data of the sampled carbonate chimney suggest late-stage (low-temperature) hydrothermal carbonate chimney formation during strongly evaporative lake conditions at the time of low-Mg calcite precipitation. U–Th age dating suggests that the chimneys formed no earlier than 0.82 kyr BP (0.28 ± 0.54).

Description: We present the first full water column Nd isotope (εNd) and concentration data for Caribbean seawater, as well as for stations close to the Orinoco River mouth and in the Florida Straits. The surface inflow into the southeastern Caribbean via the Guyana Current is characterized by an εNdsignature of −10.9, which is a consequence of the mixing of relatively unradiogenic εNdsignatures (−13.6) supplied by the Orinoco River with contributions from the Amazon River (∼−10). Despite the proximity to land, sub-surface and intermediate waters within the Caribbean largely retain the εNdsignatures of their source water masses in the Atlantic. In contrast, the deep waters of the Caribbean show εNdsignatures at least 3 εNdunits more radiogenic than the inflowing Upper North Atlantic Deep Water (UNADW). A εNdshift from −13 to −9.7 can be explained by addition of radiogenic Nd to the deep Caribbean through weathering inputs from land. However, in order to balance such large shifts in εNdwith at the same time modest increases in Nd concentrations, Nd must also be removed from seawater within the basin. It is suggested that the long residence time of deep waters in the Caribbean allows significant interaction of seawater with sinking particles and seafloor sediments resulting in more radiogenic values. These findings have implications for the use of εNdas a proxy for paleocirculation in restricted basins, in which the residence times of the deep waters are long.

Description: We investigated the zooplankton community in two different areas of the Baleares Archipelago, Western Mediterranean, using data obtained in autumn (December 2009) and summer (July 2010). Micrometazooplankton and mesozooplankton samples were collected in the 0-200 m layer above the shelf (200 m) and the slope (900 m) of each area by a 53 mu m and a 200 mu m mesh size net respectively. The zooplankton biomass (expressed as dry weight) was higher in autumn than in summer (930 and 6.95 mg m(-3), respectively) with an important contribution of micrometazooplankters (29% and 41% of total biomass respectively). The latter fraction overwhelmed in the entire metazooplankton abundance, suggesting a non-negligible role as potential food for fish in the epipelagic waters of the Baleares archipelago. The abundance of micrometazooplankton was two-fold higher in December (3581 ind. m(-3)) than in July (1585 ind. m(-3)), represented mainly by small copepods and nauplii. Likewise, the mesozooplankton community showed smaller difference between months (554 and 390 ind. m(-3), in December and July). Micrometazooplankton abundance was higher in the northern area than in the southern area during autumn, probably linked to the presence of a front, while the opposite was found in summer. In both periods and areas copepods dominated, and within the highly diverse community ten species and their juveniles accounted for 70% of the community. In both areas, Clausocalanus (C pergens + paululus and C. arcuicornis), Paracalanus parvus, Oncaea media, Oithona plumifera and Acartia clausi were abundant in autumn, whereas Centropages typicus, Temora stylifera and Mecynocera clausi were mainly present in summer. ANOSIM analysis revealed significant differences in the mesozooplankton community composition between months while differences between areas were detected only in summer

Description: The paleoceanographic development of the eastern Fram Strait during the transition from the cold Late Glacial and into the warm Early Holocene was elucidated via a multiproxy study of a marine sediment record retrieved at the western Svalbard slope. The multiproxy study includes analyses of planktic foraminiferal fauna, bulk sediment grain size and CaCO3 content in addition to Mg/Ca ratios and stable isotopes (delta C-13 and delta O-18) measured on the planktic foraminifer Neogloboquadrina pachyderma. Furthermore paleosubsurface water temperatures were reconstructed via Mg/Ca ratios (sSST(Mg/Ca)) and transfer functions (sSST(Transfer)) enabling comparison between the two proxies within a single record. The age model was constrained by four accelerator mass spectrometry (AMS) C-14 dates. From 14,000 to 10,300 cal yr B.P. N. pachyderma dominated the planktic fauna and cold polar sea surface conditions existed. The period was characterized by extensive sea ice cover, iceberg transport and low subsea surface temperatures (sSST(Transfer) similar to 2.1 degrees C; sSST(Mg/Ca) similar to 3.5 degrees C) resulting in restricted primary production. Atlantic Water inflow was reduced compared to the present-day and likely existed as a subsurface current. At ca. 10,300 cal yr B.P. Atlantic Water inflow increased and the Arctic Front retreated north-westward resulting in increased primary productivity, higher foraminiferal fluxes and a reduction in sea ice cover and iceberg transport. The fauna rapidly became dominated by the subpolar planktic foraminifer Turborotalita quinqueloba and summer sSST(Transfer) increased by similar to 3.5 degrees C. Concurrently, the sSST(Mg/Ca) recorded by N. pachyderma rose only similar to 0.5 degrees C. From ca. 10,300 to 8600 cal yr B.F. the average sSST(Mg/Ca) and sSST(Transfer) were similar to 4.0 degrees C and similar to 55 degrees C, respectively. The relatively modest change in sSST(Mg/Ca) compared to sSST(Transfer) can probably be tied to a change of the main habitat depth and/or shift in the calcification season for N. pachyderma during this period.

Description: The East Scotia subduction zone, located in the Atlantic sector of the Southern Ocean, hosts a number of hydrothermal sites in both back-arc and island-arc settings. High temperature (〉348 °C) ‘black smoker’ vents have been sampled at three locations along segments E2 and E9 of the East Scotia back-arc spreading ridge, as well as ‘white smoker’ (〈212 °C) and diffuse (〈28 °C) hydrothermal fluids from within the caldera of the Kemp submarine volcano. The composition of the endmember fluids (Mg = 0 mmol/kg) is markedly different, with pH ranging from 〈1 to 3.4, [Cl−] from ∼90 to 536 mM, [H2S] from 6.7 to ∼200 mM and [F−] from 35 to ∼1000 μM. All of the vent sites are basalt- to basaltic andesite-hosted, providing an ideal opportunity for investigating the geochemical controls on rare earth element (REE) behaviour. Endmember hydrothermal fluids from E2 and E9 have total REE concentrations ranging from 7.3 to 123 nmol/kg, and chondrite-normalised distribution patterns are either light REE-enriched (LaCN/YbCN = 12.8–30.0) with a positive europium anomaly (EuCN/Eu∗CN = 3.45–59.5), or mid REE-enriched (LaCN/NdCN = 0.61) with a negative Eu anomaly (EuCN/Eu∗CN = 0.59). By contrast, fluids from the Kemp Caldera have almost flat REE patterns (LaCN/YbCN = 2.1–2.2; EuCN/Eu∗CN = 1.2–2.2). We demonstrate that the REE geochemistry of fluids from the East Scotia back-arc spreading ridge is variably influenced by ion exchange with host minerals, phase separation, competitive complexation with ligands, and anhydrite deposition, whereas fluids from the Kemp submarine volcano are also affected by the injection of magmatic volatiles which enhances the solubility of all the REEs. We also show that the REE patterns of anhydrite deposits from Kemp differ from those of the present-day fluids, potentially providing critical information about the nature of hydrothermal activity in the past, where access to hydrothermal fluids is precluded.

Description: Two ∼6 m long sediment cores were collected along the ∼300 m isobath on the Alaskan Beaufort Sea continental margin. Both cores showed distinct sulfate-methane transition zones (SMTZ) at 105 and 120 cm below seafloor (cmbsf). Sulfate was not completely depleted below the SMTZ but remained between 30 and 500 μM. Sulfate reduction and anaerobic oxidation of methane (AOM) determined by radiotracer incubations were active throughout the methanogenic zone. Although a mass balance could not explain the source of sulfate below the SMTZ, geochemical profiles and correlation network analyses of biotic and abiotic data suggest a cryptic sulfur cycle involving iron, manganese and barite. Inhibition experiments with molybdate and 2-bromoethanesulfonate (BES) indicated decoupling of sulfate reduction and AOM and competition between sulfate reducers and methanogens for substrates. While correlation network analyses predicted coupling of AOM to iron reduction, the addition of manganese or iron did not stimulate AOM. Since none of the classical archaeal anaerobic methanotrophs (ANME) were abundant, the involvement of unknown or unconventional phylotypes in AOM is conceivable. The resistance of AOM activity to inhibitors implies deviation from conventional enzymatic pathways. This work suggests that the classical redox cascade of electron acceptor utilization based on Gibbs energy yields does not always hold in diffusion-dominated systems, and instead biotic processes may be more strongly coupled to mineralogy.

Description: Elevated anthropogenic pCO2 can delay growth and impair otolith structure and function in the larvae of some fishes. These effects may concurrently alter the larva’s proteome expression pattern. To test this hypothesis, Atlantic herring larvae were exposed to ambient (370 μatm) and elevated (1800 μatm) pCO2 for one-month. The proteome structure of the larvae was examined using a 2-DE and mass spectrometry. The length of herring larvae was marginally less in the elevated pCO2 treatment compared to the control. The proteome structure was also different between the control and treatment, but only slightly: the expression of a small number of proteins was altered by a factor of less than 2-fold at elevated pCO2. This comparative proteome analysis suggests that the proteome of herring larvae is resilient to elevated pCO2. These observations suggest that herring larvae can cope with levels of CO2 projected for near future without significant proteome-wide changes.

Description: The isotope composition of reactive iron (Fe) in marine sediments and sedimentary rocks is a promising tool for identifying Fe sources and sinks across ocean basins. In addition to cross-basinal Fe redistribution, which can modify Fe isotope signatures, Fe minerals also undergo diagenetic redistribution during burial. The isotope fractionation associated with this redistribution does not affect the bulk isotope composition, but complicates the identification of mineral-specific isotope signatures. Here, we present new Fe isotope data for Peru margin sediments and revisit previously published data for sediments from the California margin to unravel the impact of early diagenesis on Fe isotope compositions of individual Fe pools. Sediments from oxic California margin sites are dominated by terrigenous Fe supply with Fe release from sediments having a negligible influence on the solid phase Fe isotope composition. The highly reactive Fe pool (sum of Fe bound to (oxyhydr)oxide, carbonate, monosulfide and pyrite) of these sediments has a light isotope composition relative to the bulk crust, which is consistent with earlier studies showing that continental weathering shifts the isotope composition of Fe (oxyhydr)oxides to lighter values. Ferruginous sedimentswithin the Peruvian oxygen minimumzone are depleted in Fe relative to the lithogenic background, which we attribute to extensive Fe release to the water column. The remaining highly reactive Fe pool has a heavier isotope composition compared to California margin sediments. This observation is in agreement with the general notion of an isotopically light benthic Fe efflux. Most of the reactive Fe delivered and retained in the sediment is transferred into authigenic mineral phases within the topmost 10 to 20 cm of the sediments. We observe a first-order relationship between the extent of pyritization of Fe monosulfide and the isotope composition of authigenic pyrite. With increasing pyritization, the isotope composition of authigenic pyrite approaches the isotope composition of the highly reactive Fe pool. We argue that the isotope composition of authigenic pyrite or other Fe minerals that may undergo pyritization may only be used to trace water column sources or sinks if the extent of pyritization is separately evaluated and either close to 100% or 0%. Alternatively, one may calculate the isotope composition of the highly reactive Fe pool, thereby avoiding isotope effects due to internal diagenetic redistribution. In depositional settings with high Fe but lowsulfide concentrations, source and sink signatures in the isotope composition of the highly reactive Fe pool may be compromised by sequestration of Fe within authigenic silicate minerals. Authigenic silicate minerals appear to be an important burial phase for reactive Fe below the Peruvian oxygen minimum zone.

Description: More than 1500 km of multi-channel seismic reflection profiles combined with ICDP (International Continental Scientific Drilling Program) drilling data, provide important insights into the stratigraphic evolution of Lake Van, eastern Turkey. Three major basins (Tatvan, Northern and the Deveboynu basins) comprise the main lake basin and are separated by morphological highs (Ahlat ridge and Northern ridge). Moreover, NE–SW faults, parallel to the general tectonic lineament of the area, dominate the entire basin and are in charge of creating graben and half-graben structures. Well-developed prograding deltaic sequences on top of the basement were recognized by seismic stratigraphy analysis. Most likely, they formed during the initial flooding of Lake Van ∼600 ka. The Tatvan basin sediments are dominated by mass-flow deposits of various origins alternating with undisturbed lacustrine sediments including distinct tephra layers. Faulting along the Tatvan basin margins may have triggered margin-wide slope failures. Ahlat ridge started to form between ca 340 ka–290 ka. Since then, Ahlat ridge was sheltered from major mass-flows due to its elevation. Hence, slow lacustrine sedimentation has prevailed throughout lake history on Ahlat ridge, which was the location of the main drill site during the ICDP. Several lake level fluctuations are evident on the eastern slope area but the deep basins were permanently covered by water. A significant lake-level low stand (ca 600 ka BP) was found at ∼610 m below present lake level. The setting of the lake changed at about 30 ka. Tectonic activity appears to have waned significantly as the mass-transport deposition decreased across the Tatvan basin while normal undisturbed lacustrine sedimentation prevailed. A different setting is found in the Northern basin from ca 90 ka to Present, especially due to the strong influx of mostly volcaniclastic turbidites causing sedimentation rates to be about 3.5 times higher (drill Site 1), than at Site 2 (Ahlat ridge).

Description: Understanding the biogeochemical cycle of magnesium (Mg) is not only crucial for terrestrial ecology, as this element is a key nutrient for plants, but also for quantifying chemical weathering fluxes of Mg and associated atmospheric CO2 consumption, requiring distinction of biotic from abiotic contributions to Mg fluxes exported to the hydrosphere. Here, Mg isotope compositions are reported for parent basalt, bulk soils, clay fractions, exchangeable Mg, seasonal soil solutions, and vegetation for five types of volcanic soils in Iceland in order to improve the understanding of sources and processes controlling Mg supply to vegetation and export to the hydrosphere. Bulk soils (δ26Mg = -0.40±0.11‰) are isotopically similar to the parent basalt (δ26Mg = -0.31‰), whereas clay fractions (δ26Mg = -0.62±0.12‰), exchangeable Mg (δ26Mg = -0.75 ± 0.14 ‰), and soil solutions (δ26Mg = -0.89 ± 0.16 ‰) are all isotopically lighter than the basalt. These compositions can be explained by a combination of mixing and isotope fractionation processes on the soil exchange complex. Successive adsorption-desorption of heavy Mg isotopes leads to the preferential loss of heavy Mg from the soil profile, leaving soils with light Mg isotope compositions relative to the parent basalt. Additionally, external contributions from sea spray and organic matter decomposition result in a mixture of Mg sources on the soil exchange complex. Vegetation preferentially takes up heavy Mg from the soil exchange complex (Δ26Mgplant-exch = +0.50±0.09‰), and changes in δ26Mg in vegetation reflect changes in bioavailable Mg sources in soils. This study highlights the major role of Mg retention on the soil exchange complex amongst the factors controlling Mg isotope variations in soils and soil solutions, and demonstrates that Mg isotopes provide a valuable tool for monitoring biotic and abiotic contributions of Mg that is bioavailable for plants and is exported to the hydrosphere.

Description: Highlights: • Slice and transient simulations of Holocene climate change were performed. • Spatial–temporal patterns of Holocene Asian summer precipitation are investigated. • A tripole pattern of summer precipitation can be seen over monsoonal Asia. • Insolation change is a key factor for Holocene Asian summer monsoon change. • Internal feedbacks are important to Holocene Asian summer precipitation changes. Abstract: Paleoclimate proxy records of precipitation/effective moisture show spatial–temporal inhomogeneous over Asian monsoon and monsoon marginal regions during the Holocene. To investigate the spatial differences and diverging temporal evolution over monsoonal Asia and monsoon marginal regions, we conduct a series of numerical experiments with an atmosphere–ocean–sea ice coupled climate model, the Kiel Climate Model (KCM), for the period of Holocene from 9.5 ka BP to present (0 ka BP). The simulations include two time-slice equilibrium experiments for early Holocene (9.5 ka BP) and present-day (0 ka BP), respectively and one transient simulation (HT) using a scheme for model acceleration regarding to the Earth's orbitally driven insolation forcing for the whole period of Holocene (from 9.5 to 0 ka BP). The simulated summer precipitation in the equilibrium experiments shows a tripole pattern over monsoonal Asia as depicted by the first modes of empirical orthogonal function (EOF1) of H0K and H9K. The transient simulation HT exhibits a wave train pattern in the summer precipitation across the Asian monsoon region associated with a gradually decreased trend in the strength of Asian summer monsoon, as a result of the response of Asian summer monsoon system to the Holocene orbitally-forced insolation change. Both the synthesis of multi-proxy records and model experiments confirm the regional dissimilarity of the Holocene optimum precipitation/effective moisture over the East Asian summer monsoon region, monsoon marginal region, and the westerly-dominated areas, suggesting the complex response of the regional climate systems to Holocene insolation change in association with the internal feedbacks within climate system, such as the air-sea interactions associated with the El Nino/Southern Oscillation (ENSO) and shift of the Intertropical Convergence Zone (ITCZ) in the evolution of Asian summer monsoon during the Holocene.

Description: Improving the understanding of digestive physiology in first feeding larvae is a prerequisite for advancing diet formulations and feeding protocols. In marine fish larvae that lack a stomach at first-feeding trypsin represents the main proteolytic enzyme. CCK is one of the key regulators of digestive enzyme secretion in adult vertebrates and current knowledge suggests that it is also involved in early stages of teleosts, although this may vary between species. Here, we investigated the influence of Artemia and a commercial microdiet on the ontogenetic development of tryptic enzyme activity as an indicator for digestive capacity in first-feeding sea bass. In order to examine the regulation and feedback mechanisms in the digestive tract we followed the response of gut CCK and tryptic enzyme activity during a one-day observation depending on the feeding regime at 23 days post hatch. Larvae fed the microdiet showed a higher tryptic enzyme activity, probably as an adaptation to the higher content in complex protein in the diet. The plant protein phytohemagglutinin (PHA), added to the microdiet as a potential stimulator for the digestive system, did not induce elevated tryptic enzyme activity nor was it beneficial for growth. This was possibly due to adverse effects of too high doses. We observed an endogenous rhythm of CCK over the day, independent of the dietary treatment or short-term fasting. Higher tryptic enzyme activity in larvae fed Artemia during the day might indicate a better stimulation by live prey in the digestive tract or the superiority of a discontinuous feeding schedule in this group. We suggest that a reduction in tryptic enzyme activity after several feeding events indicates a limit in diurnal digestive capacity. Sea bass larvae are apparently able to adapt to the feeding schedule by synchronizing the tryptic enzyme activity like adult fish.

Description: We present iron (Fe) concentration and Fe isotope data for a sediment core transect across the Peru upwelling area, which hosts one of the ocean’s most pronounced oxygen minimum zones (OMZs). The lateral progression of total Fe to aluminum ratios (FeT/Al) across the continental margin indicates that sediments within the OMZ are depleted in Fe whereas sediments below the OMZ are enriched in Fe relative to the lithogenic background. Rates of Fe loss within the OMZ, as inferred from FeT/Al ratios and sedimentation rates, are in agreement with benthic flux data that were calculated from pore water concentration gradients. The mass of Fe lost from sediments within the OMZ is within the same order of magnitude as the mass of Fe accumulating below the OMZ. Taken together, our data are in agreement with a shuttle scenario where Fe is reductively remobilized from sediments within the OMZ, laterally transported within the anoxic water column and re-precipitated within the more oxic water below the OMZ. Sediments within the OMZ have increased 56Fe/54Fe isotope ratios relative to the lithogenic background, which is consistent with the general notion of benthic release of dissolved Fe with a relatively low 56Fe/54Fe isotope ratio. The Fe isotope ratios increase across the margin and the highest values coincide with the greatest Fe enrichment in sediments below the OMZ. The apparent mismatch in isotope composition between the Fe that is released within the OMZ and Fe that is re-precipitated below the OMZ implies that only a fraction of the sediment-derived Fe is retained near-shore whereas another fraction is transported further offshore. We suggest that a similar open-marine shuttle is likely to operate along many ocean margins. The observed sedimentary fingerprint of the open-marine Fe shuttle differs from a related transport mechanism in isolated euxinic basins (e.g., the Black Sea) where the laterally supplied, reactive Fe is quantitatively captured within the basin sediments. We suggest that our findings are useful to identify OMZ-type Fe cycling in the geological record.

Description: Major and trace element and Nd, Sr and Pb isotope data from c. 550 Ma-old gray granites and c. 510 Ma-old red leucogranites of the high-grade central part of the Damara orogen (Namibia) indicate a dominantly deep crustal origin. Moderately peraluminous gray granites are isotopically evolved (initial epsilon(Nd): C. - 17) and were likely derived from meta-igneous sources with late Archean to Paleoproterozoic crustal residence ages. Based on a comparison with experimental results, the granites were derived by partial melting of a granodioritic biotite gneiss at c. 900-950 degrees C and less than 10 kbar. Slightly peraluminous red leucogranites are also isotopically evolved (initial epsilon(Nd): - 15 to - 18) but have undergone extensive crystal fractionation coupled with minor contamination of mid crustal meta-pelitic material. Major and trace element data do not support closed-system fractional crystallization processes for all samples, however, some chemical features underline the importance of crystal fractionation processes especially for the leucogranites. Isotope data do not support mixing of different crust-derived melts or assimilation of crustal rocks by a mafic magma on a large scale. For the gray granites, unradiogenic Pb isotope compositions with substantial variation in Pb-207/Pb-204 at almost constant (206)pb/(204)pb, strongly negative epsilon(Nd) values and moderately radiogenic Sr isotope compositions argue for an undepleted nature of the source. High Rb/Sr ratios of the red leucogranites permit a comparison with the gray granites but similar initial ENd values indicate that the source of these granites is not fundamentally different to the source of the gray granites. The most acceptable model for both granite types involves partial melting of meta-igneous basement rocks of Archean to Proterozoic age. The consistency of the chemical data with a crustal anatectic origin and the observation that the gray granites intruded before the first peak of high-grade regional metamorphism suggests that they intruded simultaneously with crustal thickening. The red leucogranites are interpreted to be a result of crustal melting during the main peak of regional metamorphism. The heating events that promoted melting of fertile deep-crustal rocks might have been caused by the inferred high heat productivity of heat-producing radioactive elements (Th, U, K) together with crustal thickening during the main periods of orogeny

Description: We present trace element compositions, rare earth elements (REEs) and radiogenic Nd–Sr isotope analyses of Cretaceous to recent sediments of the Tarfaya basin, SW Morocco, in order to identify tectonic setting, source rocks composition and sediments provenance. The results suggest that the sediments originate from heterogeneous source areas of the Reguibat Shield and the Mauritanides (West African Craton), as well as the western Anti-Atlas, which probably form the basement in this area. For interpreting the analyzed trace element results, we assume that elemental ratios such as La/Sc, Th/Sc, Cr/Th, Th/Co, La/Co and Eu/Eu∗ in the detrital silicate fraction of the sedimentary rocks behaved as a closed system during transport and cementation, which is justified by the consistency of all obtained results. The La/Y-Sc/Cr binary and La–Th–Sc ternary relationships suggest that the Tarfaya basin sediments were deposited in a passive margin setting. The trace element ratios of La/Sc, Th/Sc, Cr/Th and Th/Co indicate a felsic source. Moreover, chondrite-normalized REE patterns with light rare earth elements (LREE) enrichment, a flat heavy rare earth elements (HREE) and negative Eu anomalies can also be attributed to a felsic source for the Tarfaya basin sediments. The Nd isotope model ages (TDM = 2.0–2.2 Ga) of the Early Cretaceous sediments suggest that sediments were derived from the Eburnean terrain (Reguibat Shield). On the other hand, Late Cretaceous to Miocene–-Pliocene sediments show younger model ages (TDM = 1.8 Ga, on average) indicating an origin from both the Reguibat Shield and the western Anti-Atlas. In contrast, the southernmost studied Sebkha Aridal section (Oligocene to Miocene–Pliocene) yields older provenance ages (TDM = 2.5–2.6 Ga) indicating that these sediments were dominantly derived from the Archean terrain of the Reguibat Shield.

Description: Highlights: • Strong intraseasonal variability of near shore plankton in Peru upwelling system. • Chlorophyll variability is driven by the intraseasonal coastally trapped waves. • Chlorophyll anomalies propagate poleward at speed of high order CTW mode. • Intraseasonal wind impacts mainly the northern shelf variability and at 20–30 days. Abstract The impact of intraseasonal coastal-trapped waves on the nearshore Peru ecosystem is investigated using observations and a regional eddy-resolving physical-ecosystem coupled model. Model results show that intraseasonal variability over the period 2000–2006 represents about one fourth of the total surface chlorophyll variance and one third of the carbon export variance on the Peruvian shelf. Evidence is presented that subsurface nutrient and chlorophyll intraseasonal variability are mainly forced by the coastally trapped waves triggered by intraseasonal equatorial Kelvin waves reaching the South American coast, and propagate poleward along the Peru shore at a speed close to that of high order coastal trapped waves modes. The currents associated with the coastal waves induce an input of nutrients that triggers a subsequent phytoplankton bloom and carbon export. The impact of the local wind-forced intraseasonal variability on the ecosystem is of a similar order of magnitude to that remotely forced in the northern part of the Peru shelf on [50–90] day time scales and dominates over the entire shelf on [20–30] day time scales.

Description: Coarse particulate organic matter (CPOM) represents a small portion of the inner shelf sediments but occurs across all river outlets. To consider the ecogeochemical fate of CPOM in such an environment, we examined both the infauna community and secondary evidence of geochemical reactions preserved in the surface sediments of the Rhône prodelta. ICP-AES, scanning electron microscopy and energy dispersive X-ray spectrometry of the CPOM showed that the fate of organic matter in this environment is driven by sulphate reduction and geochemical reactions resulting from the precipitation of sulfide due to the presence of large amounts of iron-bearing minerals. Leaf litter debris contained such high quantities of iron that after dry ashing the remaining material is easily attracted by a magnet. The observed geochemical trade-off was proposed as a mechanism that helps to maintain a bioturbating animal community that in turn contributes to the mineralization of organic matter within this suboxic environment. This study showed that the accumulation of refractory organic carbon in sediments was intimately associated with the sequestering of iron and sulphur by providing a nucleation point for mineral deposition and also that the extent of decomposition of the organic materials did not necessarily increase progressively from coarser to finer particles.

Description: A new mound field, the West Melilla mounds, interpreted as being cold-water coral mounds, has been recently unveiled along the upper slope of the Mediterranean Moroccan continental margin, a few kilometers west of the Cape Tres Forcas. This study is based on the integration of high-resolution geophysical data (swath bathymetry, parametric sub-bottom profiler), CTD casts, Acoustic Doppler Current Profiler (ADCP), ROV video and seafloor sampling, acquired during the TOPOMED GASSIS (2011) and MELCOR (2012) cruises. Up to 103 mounds organized in two main clusters have been recognized in a depth range of 299–590 m, displaying a high density of 5 mounds/km2. Mounds, 1–48 m high above the surrounding seafloor and on average 260 m wide, are actually buried by a 1–12 m thick fine-grained sediment blanket. Seismic data suggest that the West Melilla mounds grew throughout the Early Pleistocene–Holocene, settling on erosive unconformities and mass movement deposits. During the last glacial–interglacial transition, the West Melilla mounds may have suffered a drastic change of the local sedimentary regime during the late Holocene and, unable to stand increasing depositional rates, were progressively buried. At the present day, temperature and salinity values on the West Melilla mounds suggest a plausible oceanographic setting, suitable for live CWCs. Nonetheless, more data is required to groundtruth the West Melilla mounds and better constrain the interplay of sedimentary and oceanographic factors during the evolution of the West Melilla mounds.

Description: The Pan-African Damara orogen of Namibia is characterized by large-scale granitoid intrusions. Two plutons in the Northern Central Zone (NCZ) of the Damara orogen within the Okombahe district have U–Pb zircon ages of 576.2 ± 5.7 Ma and 570.9 ± 4.9 Ma that predate the time of high grade regional metamorphism which occurred between 540 and 480Ma. The intrusive rocks are magnesian high-K alkali-calcic granodiorites to granites, are enriched in HFSE and REE, and have undergone only a limited degree of fractional crystallization, and do not contain xenoliths of local country rocks. Initial isotope compositions are unevolvedwith 87Sr/86Sr between 0.704 and 0.706 and initial εNd ranging from −1.9 to−3.9. Lead isotopes are radiogenic (206Pb/204Pb: 18.32 to 18.61, 207Pb/204Pb: 15.61 to 15.69 and 208Pb/204Pb: 37.87 to 39.29) with variable 207Pb/204Pb ratios at almost constant 206Pb/204Pb and 208Pb/204Pb ratios, suggesting a derivation from ancient sources with comparatively high U/Pb but low Th/Pb ratios. The limited variations in Sr, Nd and Pb isotopes were not caused by crustal contamination or magma mixing, but instead reflect source heterogeneities. Strontium and Nd isotope compositions suggest mafic lithologies similar to amphibolites from the Kalahari Craton basement as potential sources. A comparison with amphibolite melting experiments confirms the possible derivation of the granodiorites from an amphibolitic source. Calculated maximum zircon saturation temperatures at insignificant amounts of inherited zircon, indicate intrusion temperatures of up to 900 °C. Apatite saturation temperatures are higher, up to ca. 950 °C. Pressures of 5 to 10 kbar are determined through Qz-Ab-Or systematics and are interpreted as minimum pressures at the site of melting suggesting that the granodiorites/granites represent high temperature partial melts generated in the lower crust. Although there are some compositional similarities with granites generated in subduction zones, radiogenic Pb isotope ratios and high δ18O values suggest that reprocessed amphibolitic rocks are more likely sources.

Description: Highlights: • The geochemistry of a Cretaceous Tongan fore-arc basalt (FAB) suite is reported. • The Tonga FAB suite is very similar to the Poya Terrane basalts of New Caledonia. • Similar geochemistry to IBM FAB but not associated with subduction initiation • Possibly a remnant of the hypothesized back-arc East New Caledonia Basin Abstract: The Tonga fore-arc preserves a complex history of subduction initiation, back-arc basin formation and arc volcanism which has extended from the Cretaceous to the present. In this paper, we discuss the geochemistry of a Cretaceous basalt/dolerite/gabbro suite recovered in two dredges from the Tonga fore-arc at ~ 19°S. The geochemistry of the Tonga fore-arc suite is unlike that of the uniformly depleted MORB basalts of the subducting Pacific Plate and therefore is unlikely to be accreted from Pacific Cretaceous crust. The ~ 102 Ma age obtained for one Tongan fore-arc dolerite is contemporaneous with a major phase of Cretaceous subduction-related volcanism, recorded both in detrital zircon age populations and associated volcanics from New Caledonia and New Zealand. We believe that the Tonga fore-arc basalts are a remnant of a hypothesized, once extensive Cretaceous back-arc basin, called the East New Caledonia Basin, which we propose to have existed from ~ 102 to 50 Ma. The allochthonous Poya Terrane of New Caledonia is geochemically very similar to the Tonga fore-arc basalts and represents a younger (~ 84–55 Ma) remnant of the same basin. Subduction-related Cretaceous volcanics from the SW Pacific, representing both arc and back-arc settings, all appear to have similar Zr/Nb values, suggesting a common mantle component in their petrogenesis. The Tonga fore-arc basalts are also similar to fore-arc basalts recovered from the Izu-Bonin-Mariana fore-arc, but unlike these basalts they are not associated with subduction initiation.

Description: Pteropods are an important component of the zooplankton community and hence of the food web in the Fram Strait. They have a calcareous (aragonite) shell and are thus sensitive in particular to the effects of the increasing CO2 concentration in the atmosphere and the associated changes of pH and temperature in the ocean. In the eastern Fram Strait, two species of thecosome pteropods occur, the cold water-adapted Limacina helicina and the subarctic boreal species Limacina retroversa. Both species were regularly observed in year-round moored sediment traps at ~ 200–300 m depth in the deep-sea long-term observatory HAUSGARTEN (79°N, 4°E). The flux of all pteropods found in the trap samples varied from 〈 20 to ~ 870 specimen m− 2 d− 1 in the years 2000–2009, being lower during the period 2000–2006. At the beginning of the time series, pteropods were dominated by the cold-water-adapted L. helicina, whereas the subarctic boreal L. retroversa was only occasionally found in large quantities (〉 50 m− 2 d− 1). This picture completely changed after 2005/6 when L. retroversa became dominant and total pteropod numbers in the trap samples increased significantly. Concomitant to this shift in species composition, a warming event occurred in 2005/6 and persisted until the end of the study in 2009, despite a slight cooling in the upper water layer after 2007/8. Sedimentation of pteropods showed a strong seasonality, with elevated fluxes of L. helicina from August to November. Numbers of L. retroversa usually increased later, during September/October, with a maximum at the end of the season during December/January. In terms of carbonate export, aragonite shells of pteropods contributed with 11–77% to the annual total CaCO3 flux in Fram Strait. The highest share was found in the period 2007 to 2009, predominantly during sedimentation events at the end of the year. Results obtained by sediment traps occasionally installed on a benthic lander revealed that pteropods also arrive at the seafloor (~ 2550 m) almost simultaneous with their occurrence in the shallower traps. This indicates a rapid downward transport of calcareous shells, which provides food particles for the deep-sea benthos during winter when other production in the upper water column is shut down. The results of our study highlight the great importance of pteropods for the biological carbon pump as well as for the carbonate system in Fram Strait at present, and indicate modifications within the zooplankton community. The results further emphasize the importance of long-term investigation to disclose such changes.

Description: A mass spectrometric (MS) method for the identification of iron protoporphyrin (IX) (FePTP, heme b) in marine particulate material and phytoplankton is described. Electrospray ionisation of FePTP produced the molecular Fe(III)PTP+ ion (m/z = 616) or the pseudomolecular [Fe(II)PTP + H]+ ion (m/z = 617), depending on the oxidation state of the central iron ion. Collision induced dissociation (CID) in the ion trap mass spectrometer resulted in a single detected product ion (m/z = 557) indicative of loss of ethanoic acid from a carboxylic acid side chain. Widening the isolation width to 616 ± 3 resulted in production of a mass spectrum demonstrating the distinctive isotopic ratio of the iron containing fragment, further increasing the specificity of the analysis. Selective reactant monitoring (SRM) of the fragment ion (m/z = 557) was applied to the detection of FePTP after chromatography of ammoniacal OGP extracts of marine samples. The detection limit for FePTP analysed by SRM after chromatography was 1.2 ± 0.5 fmol. For phytoplankton samples, reasonably good agreement was achieved between results obtained with SRM and those obtained by monitoring absorbance at λ = 400 nm using a diode array detector (DAD). Use of SRM for analysis of particulate material obtained from the high latitude North Atlantic allowed for the analysis of FePTP in the presence of a co-eluting compound that interfered with detection by DAD. Simultaneous collection of mass spectra from m/z = 300 to 1500 resulted in identification of the pseudomolecular ion for the interfering compound. The CID fragmentation pattern and UV–visible mass spectra indicated that the interfering compound was a previously unidentified chlorin type compound. Comparison of FePTP determined by SRM and DAD on samples where this compound could not be detected showed that results collected using the two methods correlated. The use of both MS and DAD results in a powerful tool for quantifying this important biogenic component of the particulate iron pool.

Description: Investigations in four natural traps from southeastern France have provided new and extensive information on the palaeoenvironment from the Last Glacial Maximum (LGM; 21,000 to 15,075 cal BP), the Late-glacial period (15,075 to 11,490 cal BP) and the beginning of Holocene (11,490 to 2835 cal BP). Radiocarbon and U/Th dates provided precise chronological data. In the Coulet des Roches, an LGM and a near complete Late-glacial period sequence were identified. The infilling preserved skeletons of large mammals, revealing a new faunal assemblage for southeastern France. For the first time, two distinct southern expansions of Dicrostonyx torquatus have been identified, correlated firstly to the LGM and secondly to the Late-glacial period. Dicrostonyx torquatus was found to be associated with Microtus oeconemus during the Oldest Dryas (15,075 to 18,270 cal BP). Morphological adaptations to the cold climate were indicated by some mammals (Vulpes vulpes, Mustela nivalis, Mustela erminea, Equus caballus gallicus). Among the birds, Bubo scandiacus and Pyrrhocorax graculus were found to be abundant. Palynological data suggested a very open landscape as well as a cold and rather dry climate. Rangifer tarandus remains were recovered from the Oldest Dryas layers of Aven des Planes. During the Allerød, a wooded environment permitted the dispersal of Cervus elaphus, Sus scrofa, Tetrao urogallus as well as reptiles and amphibians. Holocene sequences existed in these two natural traps as in Aven Souche n° 1 and n° 2. At this time, a sparsely wooded landscape covered much of the area. Cervus elaphus and Tetrao urogallus were still present with Canis lupus, Lynx lynx and Felis silvestris. Areas of open landscape were occupied by Otis tarda. During the Bronze Age (2200 to 800 cal BC) and Iron Age (800 to 50 cal BC), Aven des Planes, Aven Souche n° 1 and n° 2 were used by humans and had a sepulchral destination.

Description: Fifteen Lateglacial to Holocene rhyolitic, dominantly primary tephra layers piston-cored and drilled (ICDP Paleovan drilling project) in western Lake Van (eastern Anatolia, Turkey) were precisely correlated to either of the two adjacent and active large volcanoes Nemrut and Süphan based on shard textures, mineralogy and mineral and glass compositions. The young peralkaline (comenditic to pantelleritic) primary rhyolitic Nemrut tephras are characterized by anorthoclase, hedenbergitic to augitic clinopyroxene, fayalitic olivine, minor quartz, and rare accessory chevkinite and zircon. Phenocrysts in subalkaline primary rhyolitic Süphan tephras are chiefly oligoclase-labradorite, with minor K-rich sanidine in some, biotite, amphibole, hypersthene, rare augitic clinopyroxene, relatively common allanite and rare zircon. Two contrasting explosive eruptive modes are distinguished from each other: episodic (Süphan) and periodic (Nemrut). The Lateglacial Süphan tephra swarm covers a short time interval of ca. 338 years between ca. 13,078 vy BP and 12,740 vy BP, eruptions having occurred statistically every ca. 42 years with especially short intervals between V-11 (reworked) and V-14. Causes for the strongly episodic Süphan explosive behavior might include seismic triggering of a volcano–magma system unable to erupt explosively without the benefit of external triggering, as reflected in pervasive faulting preceding the Süphan tephra swarm. Seismic triggering may have caused the rise of more mafic (“trachyandesitic”) parent magma, heating near-surface pockets of highly evolved magma – that might have formed silicic domes during this stage of volcano evolution – resulting in ascent and finally explosive fragmentation of magma essentially by external factors, probably significantly enhanced by magma–water/ice interaction. Explosive eruptions of the Nemrut volcano system, interpreted to be underlain by a large fractionating magma reservoir, follow a more periodic mode of (a) long-term relatively constant supply of parent magma, (b) evolution by low pressure crystal fractionation resulting in sporadic relatively low-volume eruption of trachytic and minor rhyolitic magmas, (c) evolution of a large magma reservoir to the point of highly explosive large-volume peralkaline rhyolitic Plinian eruptions at temporal intervals of ca. 20–40 ky, some accompanied by ignimbrites and inferred caldera collapse. A striking tephra gap between ca. 14 ka and ca. 30 ka, i.e. during glacial climate conditions, is postulated to be due to climate-forcing via lithosphere unloading following deglaciation.

Description: We examine ocean changes in response to changes in paleogeography from the Cretaceous to present in an intermediate complexity model and in the fully coupled CCSM3 model. Greenhouse gas concentrations are kept constant to allow a focus on effects arising from changing continental configurations. We find consistent and significant geography-related Cenozoic cooling arising from the opening of Southern Ocean (SO) gateways. Both models show significant deep ocean cooling arising from tectonic evolution alone. Simulations employing continental configurations associated with greenhouse climates, namely the Turonian and the Eocene simulations, systematically exhibit warm deep ocean temperatures at elevated pCO2 close to 10 °C. In contrast, continental configurations associated with (later) icehouse climates are associated with cooler deep ocean temperatures at identical pCO2, arising from a progressive strengthening of the Antarctic Circumpolar Current. This suggests that a component of the Cenozoic benthic cooling trend recorded in oxygen isotopes could arise directly from changes in continental configuration, and so be partially decoupled from the Cenozoic greenhouse gas history. In this paper we will present our model results against the background of an extensive review of previous work on ocean gateways and additional modelling results from several other global climate models.

Description: A 844 cm long core PS51/118-3 (77°53.54′ N; 132°11.92′ E) recovered from the upper slope (122 m water depth) of the Laptev Sea (Russian Arctic) has been studied for pollen, spores and aquatic palynomorphs, including freshwater green algae and cysts of marine dinoflagellates. The age model was established on the basis of radiocarbon dates obtained on marine bivalve mollusk shells. The available dates suggest that the analyzed sediment was accumulated during the last ca. 10.8 cal. ka and reveal two intervals with markedly different sedimentation rates, reflecting the sedimentary regime changes of the Laptev Sea shelf during postglacial sea-level rise. Very high sedimentation rates (ca. 4.7 mm per year) in the lower part of the core (120–866 cm) between ca. 9.2 and 10.8 cal. ka BP reflect lower-than-present sea levels, high erosion activity and much closer position of the palaeo-shoreline with the Lena and Yana river mouths to the core site. Dramatic decrease in sedimentation rates (ca. 0.1 mm per year) during the middle and late Holocene interval reflects high sea-level and decreased amount of suspended material transported to the outer shelf by rivers. Despite the location of the core site at the continental slope and far away from the modern coastline pollen, spores and fresh-water algae constitute a major part of the microfossils throughout the whole record, indicating great impact of the Lena and Yana rivers and possibly prevalent wind regime on the pollen and non-pollen-palynomorph (NPP) assemblages. Although a number of short-term (decadal to multi-century) oscillations deviate from the mean Holocene values, pollen taxa percentages and pollen-based numerical biome reconstructions do not show very clear trends. The latter is likely a result of the mixed environmental signal and complex pollen contribution of several large environmental regions and vegetation zones of Siberia drained by the Lena and Yana rivers. The greater pollen contribution of the forested regions to the PS51/118-3 record reflects higher pollen production of the boreal trees and shrubs over the low-productive Arctic vegetation. The intervals of the relative increase in the tundra biome scores in the PS51/118-3 record reflect decreased arboreal pollen production or/and increased landscape openness within the pollen source area and can be correlated (within the uncertainty of the age models) with the cold episodes observed in the Greenland ice and North Atlantic sediment records.

Description: Cells contain several mechanosensing components that transduce mechanical signals into biochemical cascades. During cell–ECM adhesion, a complex network of molecules mechanically couples the extracellular matrix (ECM), cytoskeleton, and nucleoskeleton. The network comprises transmembrane receptor proteins and focal adhesions, which link the ECM and cytoskeleton. Additionally, recently identified protein complexes extend this linkage to the nucleus by linking the cytoskeleton and the nucleoskeleton. Despite numerous studies in this field, due to the complexity of this network, our knowledge of the mechanisms of cell–ECM adhesion at the molecular level remains remarkably incomplete. Herein, we present a review of the structures of key molecules involved in cell-ECM adhesion, along with an evaluation of their predicted roles in mechanical sensing. Additionally, specific binding events prompted by force-induced conformational changes of each molecule are discussed. Finally, we propose a model for the biomechanical events prominent in cell–ECM adhesion.

Description: The rhyolitic Plinian eruption of the Chilean Chaitén Volcano, initiated on May 2, 2008, suddenly introduced abundant pyroclastic sediments in the Blanco River catchment area, which experienced important modifications. Before May 2, the river was characterised by gravelly and moderate to low-sinuosity channels crossing a vegetated and locally urbanised (Chaitén City) floodplain. This river, limited by steep and densely forested highlands, was connected with the Pacific Ocean via a tidally-influenced delta plain. After heavy rains in May 11–20, the river discharge increased and triggered several responses including logjam formation and breakage, crevassing, avulsion (and channel abandonment), changes in the pattern and dimensions of channels, and construction of a new delta plain area. In this context, the goals of this contribution were: i) to document the sedimentological processes within a detailed geomorphic framework and ii) to understand the influence of logjams on fluvial dynamics. Upstream of the logjam zone, the deposits are mostly composed of ash and lapilli with abundant palaeovolcanic (epiclastic) sediments, which were produced by dilute currents and debris flows. Downstream of the logjam zone, deposits are composed by ash and lapilli, both pumice-rich and lacking important participation of older (epiclastic) sediments. The abandoned and filled palaeochannel, and the proximal part of crevasse splays experienced transient dilute flows with variable sediment concentration and, subordinately, hyperconcentrated flows. The distal sectors of crevasse splays mostly record settling from suspension. At the delta plain, tephra transported by the Blanco River was mixed with older sediments by tide and wave action (dilute flows). We conclude that immediately after eruption, both geomorphic and sedimentary processes of the river were mainly controlled by a combination of high availability of incoherent pyroclastic sediments on steep slopes, abundant rains, large logs that jammed the river and huge areas of devastated forest. Logjams played an important role in the river response to the volcanic eruption; they were responsible of the marked compositional change recorded upstream and downstream of the logjam zone and its breakage resulted in downstream flooding and avulsion. The likelihood of formation of logjams in rivers draining forested volcanic areas should be considered in the evaluation of volcanic hazards related to Plinian eruptions.

Description: More than a decade since the estimation of global subducting sediment (GLOSS), an expanding inductively coupled plasma mass spectrometry dataset for trace elements motivates a new assessment of the bulk sediment flux into deep-sea trenches and an update, GLOSS-II. The specific focus here is on key elements in solid earth recycling that are now better constrained by new data: Li, Be, B, Nb, Ta, Pb, Th, and U. The abundances of these elements reflect, to first order, dilution of continental detritus by biogenic opal and carbonate and, second, various continental and marine processes, such as the extent of continental weathering (Li/K2O), hydrogenous versus hydrothermal oxides (Pb/Fe), biophosphate accumulation and exposure age on the seafloor (Th and U), and organic carbon burial (U). The Be/K2O ratio (0.86 ± 0.04) and Nb/Ta ratio (14 ± 1) of terrigenous marine sediments reflect average upper continental crust and indeed refine those estimates. Given these new systematics, along with newly published data, revised bulk sediment compositions are calculated for 16 of the 25 trenches included in GLOSS. Two major additional margins are newly assessed (New Zealand-Hikurangi and Chile). Many element budgets are substantially revised for individual trenches, particularly Rb, Cs, Nb, and Pb. A new global weighted average, GLOSS-II, is similar to GLOSS (within 10% relative abundance) for many elements, with more significant changes (up to 50%) in Rb, Cs, Rb/Sr, Nd/Hf, and U/Th. The updated trench estimates provide new insights into sediment recycling at subduction zones, particularly for Li, Be, and Nb. The mass flux of Li subducted into different trenches correlates strongly with the Li/Y ratio in adjacent volcanic arcs, pointing to a direct control on Li enrichment in arcs by subducted sediment. Such a control may be consistent with Li-isotope variations in some arcs, with little fractionation required in the slab or mantle. On the other hand, arcs do not reflect the common Be/K2O ratio of most sediments and show fractionation to higher and lower ratios. These fractionations may relate to the different thermal structure of different slabs and/or subducted sediment versus basalt contributions. Sediments vary significantly in their Nb anomaly (i.e., Nb depletion with respect to La and Th), and some arcs inherit the sedimentary Nb anomaly (e.g., South Sandwich) with no new fractionation in the subduction zone, while others (e.g., Marianas and Aleutians) likely require residual rutile in the slab. The Nb anomaly is thus a nearly ubiquitous feature in arcs that has a complex origin, dependent on at least three variables: the sedimentary Nb anomaly, the presence of rutile in the slab (likely driven by Fe2 +, Fe3 +, and/or Ti abundances in the sediments), and Nb/La variation in the mantle. Trench sediments and GLOSS-II should thus continue to be useful in elucidating processes occurring in subduction zones, the continents, and the mantle.

Description: Tracers can be used to make quantitative inferences about the physical processes of mixing and advection in the ocean. After describing the nature of mixing in the ocean, the theoretical framework of tracer distribution analysis is discussed, starting with the derivation of advection–diffusion equations and tracer age dating. Next follows a description of three commonly used approaches, namely, optimum multiparameter analysis, transit time distributions, and tracer contour inverse analysis. Finally, the author discusses example applications for both steady-state (natural) tracers and transient (anthropogenic) tracers, followed by an application of tracer age dating and tracer release experiments.

Description: Protists (unicellular eukaryotes) play important roles in marine ecosystems but are tremendously diverse and many remain uncharacterized. Deep-sequencing of a universal marker gene has helped resolve community composition patterns among rare and abundant protistan sequence groups in coastal European waters.

Description: The described protocol is a simple and easily implemented method for making dynamic micropatterns for cell culture. It is based on the use of a surface coating material (azido-PLL-g-PEG (APP)) that initially repels cells, but which can be made strongly adherent by addition of a small functional peptide (BCN–RGD) to the cell culture medium. The method can be applied to trigger the adhesion, migration, or shape change of single cells or of populations of cells, and it can be used to create patterned cocultures. The entire process can be subdivided into three main parts. The first part describes the creation of patterned APP substrates. The second part describes cell seeding and “click” triggering of cell adhesion; the final part describes variations that allow the overlay of multiple patterns or the creation of patterned cocultures. The APP coating of substrates and the triggering of adhesion only involves treating the surface with aqueous stock solutions, allowing any biology lab to adopt this technique.

Description: Experiments from May to December measuring selective grazing and egestion of different phytoplankton taxa in natural Saginaw Bay (Lake Huron) seston by shallow-water morph quagga mussels (Dreissena bugensis rostriformis) showed that the mussels were highly selective filter feeders and that their net clearance rates on different species ranged widely, resulting in food consumption that was strongly driven by seasonal phytoplankton dynamics. Overall, net clearance rates by quagga mussels on the entire phytoplankton assemblage were similar to those observed for zebra mussels (Dreissena polymorpha) during the 1990s. Phytoplankton taxon, rather than size, was more important to food selection since quagga mussels cleared similar sized but different species of algae at very different rates. In contrast to many studies with zebra mussels, larger-sized algae such as Dinobryon divergens, Aulacoseira italica, Fragilaria crotonensis, and Anabaena were cleared at high rates and rejected at lower rates than many smaller species within the same broad taxonomic group. We suspect that these differences between dreissenid species do not stem from species differences but methodological factors and phytoplankton composition of systems studied. Small-sized diatoms, green algae with thick cell walls (Scenedesmus and Oocystis), and colonial cyanobacteria with gelatinous sheaths (Aphanocapsa, Chroococcus, and Microcystis) were cleared at low rates and rejected in high proportion in pseudofeces or feces during all seasons. We describe the likely mechanisms of pre- and post-ingestive behavior that explain these differences, which relate to phytoplankton size, morphology, cell wall characteristics, and chemical composition. Changes in the Great Lakes phytoplankton communities are consistent with mussel grazing preferences.

Description: The Jiaodong Terrane of the Eastern Shandong Complex in the Eastern Block of the North China Craton (NCC) consists predominantly of Archean granitoid gneisses with minor supracrustal rock enclaves or lenses. This study presents new zircon LA-ICP-MS U–Pb and Lu–Hf isotopic data for these lithologies, which help to better understand the Archean crustal evolution of the Eastern Block of the NCC. Magmatic zircon U–Pb data reveal that zircons in the supracrustal rocks and granitoid gneisses were generated by multi-stage events at ~ 2.9 Ga, ~ 2.7 Ga and ~ 2.5 Ga. Metamorphic zircon U–Pb data obtained for these rocks show distinct metamorphic ages at ~ 2.50 and ~ 1.9–1.8 Ga, suggesting that the Jiaodong Terrane experienced a regional metamorphic event at the end of the Neoarchean and encountered reworking by a tectonothermal event that was associated with the formation of the Paleoproterozoic Jiao–Liao–Ji Belt. Magmatic zircons have variable εHf(t) values from − 5.5 to + 7.7 with model ages of 3.92–2.57 Ga, of which most εHf(t) values are positive with a predominant peak of model ages at 3.4–3.1 Ga and a subordinate peak at 2.8–2.7 Ga. These Hf features reveal major juvenile crustal growth stages with significant additions of older crustal materials at 3.4–3.1 Ga and 2.8–2.7 Ga, and a crustal reworking event with minor juvenile additions at ~ 2.5 Ga in the Jiaodong Terrane.

Description: The central Liaodong Peninsula is located in the northwestern part of the Jiao-Liao-Ji Belt in the Eastern Block of the North China Craton. Surface rocks in this region are voluminous meta-mafic rocks, which mainly comprise amphibolite and metamorphic gabbro or diabase. We present zircon cathodoluminescence images, U–Pb dates, and Lu–Hf isotope data, as well as whole-rock geochemical data for these rocks, in order to constrain the tectonic nature and evolution of the Jiao-Liao-Ji Belt. Zircons from these meta-mafic rocks can be divided into two groups, with one having a typical magmatic origin and the other a metamorphic origin. Zircon U–Pb dating and Lu–Hf isotopic results show that the magmatic zircons have two peak ages at 2503 and 2154 Ma, with the former have ɛHf = +7.1 to +8.1 and single-stage model ages (THf) = 2.50–2.55 Ga, indicating that these captured or inherited zircons formed at ca. 2.50 Ga by partial melting of coeval juvenile crust. The younger magmatic zircons have ɛHf = +3.2 to +9.6, mainly varying from +7.4 to +9.6 (average = +8.7), and THf = 2.15–2.34 Ga (peak at 2.19 Ga), suggesting that the meta-mafic rocks were emplaced at ca. 2.15 Ga and derived by partial melting of depleted mantle. The metamorphic zircons yield a peak age of 1897 Ma and have ɛHf = −4.5 to +6.8. These zircons can be further divided into three groups on the basis of Hf isotope data (i.e., ɛHf = −4.5 to −2.3, −0.6 to +1.0, and +3.1 to +6.8; THf = 2.39–2.54, 2.26–2.39, and 2.03–2.11 Ga, respectively), indicating they were derived by reworking of Neoarchean–Paleoproterozoic ancient crust and some Paleoproterozoic juvenile crust. Thus there existed two crustal growth events at 2.50 and 2.15 Ga and one reworking event at ca. 1.90 Ga in the Eastern Block. Geochemical data show that these meta-mafic rocks are characterized by: SiO2 = 47.3–49.8 wt.%; TiO2 = 0.97–1.59 wt.%; K2O = 0.39–1.95 wt.%; Na2O/K2O = 1.03–4.85; Mg# = 39–52; Cr = 29–247 ppm; and Ni = 24.4–73.4 ppm. These features, combined with low total rare earth element concentrations (ΣREE), relative enrichment in light REE, significant positive Rb, Ba, K, and P anomalies, and depletions in high-field strength elements (e.g., Nb, Ta, and Ti), indicate derivation by partial melting of depleted lithospheric mantle that had been metasomatized by subduction-derived fluids, with little or no crustal contamination during magma ascent. Given our dating results and the regional geological framework, we propose that the subduction in the eastern Longgang Block took place at least in age of 2.15 Ga, and that the meta-mafic rocks in the central Liaodong Peninsula may have formed in a back-arc basin. However, the tectonic location of this magmatic arc and its relationship with the Nangrim Block need to be further studied to confirm this hypothesis.

Description: Rising stable nitrogen isotope ratios (δ15N) in dated sediment records of the German Bight/SE North Sea track river-induced coastal eutrophication over the last 2 centuries. Fully exploiting their potential for reconstructions of pristine conditions and quantitative analysis of historical changes in the nitrogen cycle from these sediment records requires knowledge on processes that alter the isotopic signal in non-living organic matter (OM) of sinking particles and sediments. In this study, we analyze the isotopic composition of particulate nitrogen (PN) in the water column during different seasons, in surface sediments, and in sediment cores to assess diagenetic influences on the isotopic composition of OM. Amino acid (AA) compositions of suspended matter, surface sediments, and dated cores at selected sites of the German Bight serve as indicators for quality and degradation state of PN. The δ15N of PN in suspended matter had seasonal variances caused by two main nitrate sources (oceanic and river) and different stages of nitrate availability during phytoplankton assimilation. Elevated δ15N values (〉 20‰) in suspended matter near river mouths and the coast coincide with a coastal water mass receiving nitrate with elevated isotope signal (δ15N 〉 10‰) derived from anthropogenic input. Particulate nitrogen at offshore sites fed by oceanic nitrate having a δ15N between 5 and 6‰ had low δ15N values (〈 2‰), indicative of an incipient phytoplankton bloom. Surface sediments along an offshore–onshore transect also reflect the gradient of low δ15N of nitrate in offshore sites to high values near river mouths, but the range of values is smaller than between the end members listed above and integrates the annual δ15N of detritus. Sediment cores from the coastal sector of the gradient show an increasing δ15N trend (increase of 2.5‰) over the last 150 years. This is not related to any change in AA composition and thus reflects eutrophication. The δ15N signals from before AD 1860 represent a good estimation of pre-industrial isotopic compositions with minimal diagenetic overprinting. Rising δ13C in step with rising δ15N in these cores is best explained by increasing productivity caused by eutrophication.

Description: By accelerating the naturally-occurring carbonation of magnesian silicates, it would be possible to sequester some of the anthropogenic excess of CO2 in more geologically-stable solid magnesium carbonates. Reaction rates can be accelerated by decreasing the particle size, raising the reaction temperature, increasing the pressure, using a catalyst, and hypothetically, by bacterial addition. We aimed here at assessing quantitatively the added value of photosynthetic microbial activity on the efficiency of Mg-silicates carbonation processes. Synechococcus PCC 7942 (freshwater cyanobacteria) was selected for this study. Two magnesian silicate minerals (substrates) were chosen: a synthetic forsterite with nanometer-sized grains and an industrial ultramafic slag (scoria). All tests were performed at 20 ± 1 °C in closed and sterile 1L Schott® glass bottle reactors. With the aim to elucidate the interaction between mineral phases and bacteria, we used pH and concentration measurements, scanning and transmission electron microscopy along with Raman spectroscopy. The results show that, at ambient temperature, cyanobacteria Synechococcus can accelerate silicate dissolution (i.e. Mg2+ release) and then magnesium carbonate nucleation and precipitation by adsorption on the produced exopolymeric substances and local pH increase during photosynthesis, respectively.

Description: The Outokumpu district within the North Karelia Schist Belt in eastern Finland hosts a number of Cu–Co–Zn–Ni–Ag–Au sulfide deposits that are associated with Palaeoproterozoic ophiolitic metaserpentinites derived from depleted mantle peridotites that were subsequently tectonically interleaved with allochthonous metaturbidites. The metaperidotites have been extensively metasomatized to quartz–carbonate–calc–silicate rocks of the Outokumpu assemblage. The Outokumpu area has been affected by a multiple-phase tectonic history comprising various phases of folding and shearing followed by several faulting events. Future exploration has to expand the search into deeper areas and requires knowledge of the subsurface geology. In order to unravel the complex structure 3D geologic models of different scales have been built using a variety of information including geological aeromagnetic and gravity maps, digital terrain models, and mine cross sections as well as data like drill core logs combined with observations from underground mine galleries, structural measurements, aeromagnetic data, and seismic surveys. For crustal structures, data from seismic surveys lines have been reprocessed for our purpose. Both deposit-scale and regional-scale models allow the reconstruction of a sequence of structural events. The mined ore has formed during remobilization of a proto-ore and is closely related to shear zones (thrusts) that truncate the Outokumpu assemblage. Later faults dismembered the ore explaining the variable depth of the different ore bodies along the Outokumpu ore zone. On larger scale at least four km-scale thrust sheets, separated by major listric shear zones can be identified in the ore belt, which are internally further imbricated by subordinate shear zones. These thrusts separate a number of lens-shape metaperidotite bodies that are probably surrounded by Outokumpu assemblage rocks. Thrust stacking was followed by at least three stages of faulting that divided the ore belt into fault-bounded blocks with heterogeneous displacements: (i) faulting along NW-dipping faults with unresolved kinematics, (ii) reverse faulting along c. 50°–60° SE-dipping faults, and (iii) SW–NE to SSW–NNE striking faults which may have formed at an earlier stage and have been reactivated. The specific Outokumpu alteration assemblage around metaperidotite bodies combined with shear zones acting as path ways for fluids are the main vectors to mineralization. Seismic reflection data do not provide a simple tool to directly detect the sites of Outokumpu assemblage bodies at depth but they identify strong reflector zones which are characteristic for though not exclusive to the assemblage, shear zones can be recognized as curved dislocations in the seismic lines. Our study shows that 3D modeling, when used in combination with surface geology and other geophysical data and good knowledge about the structural evolution clearly improves the interpretation of reflectors and enables the identification of strong reflector packages as Outokumpu assemblage that, due to absent geological control, have first been mapped as “unknown reflector”. It thus enhances the chances for locating potentially economic horizons at depth and to delineate target areas for detailed exploration.

Description: Sequencing of mitochondrial gene fragments from specimens representing a wide range of geographical locations has indicated limited population structuring in Atlantic cod (Gadus morhua). We recently performed whole genome analysis based on next-generation sequencing of two pooled ecotype samples representing offshore migratory and inshore stationary cod from the North-east Atlantic Ocean. Here we report molecular features and variability of the 16.7 kb mitogenome component that was collected from the datasets. These sequences represented more than 25 times coverage of each individual and more than 1100 times coverage of each ecotype sample. We estimated the mitogenome to have evolved 14 times more rapidly than the nuclear genome. Among the 365 single nucleotide polymorphism (SNP) sites identified, 121 were shared between ecotypes, and 151 and 93 were private within the migratory and stationary cod, respectively. We found 323 SNPs to be located in protein coding genes, of which 29 were non-synonymous. One synonymous site in ND2 was likely to be under positive selection. FST measurements indicated weak differentiation in ND1 and ND2 between ecotypes. We conclude that the Atlantic cod mitogenome and the nuclear genome apparently evolved by distinct evolutionary constraints, and that the reproductive isolation observed from whole genome analysis was not visible in the mtDNA sequences.

Description: Abstract The malaria parasite Plasmodium goes through two life stages in the human host, a non-symptomatic liver stage (LS) followed by a blood stage with all clinical manifestation of the disease. In this study, we investigated a series of 2-alkynoic fatty acids (2-AFAs) with chain lengths between 14 and 18 carbon atoms for dual in vitro activity against both life stages. 2-Octadecynoic acid (2-ODA) was identified as the best inhibitor of Plasmodium berghei parasites with ten times higher potency (IC50 = 0.34 μg/ml) than the control drug. In target determination studies, the same compound inhibited three Plasmodium falciparum FAS-II (PfFAS-II) elongation enzymes PfFabI, PfFabZ, and PfFabG with the lowest IC50 values (0.28–0.80 μg/ml, respectively). Molecular modeling studies provided insights into the molecular aspects underlying the inhibitory activity of this series of 2-AFAs and a likely explanation for the considerably different inhibition potentials. Blood stages of P. falciparum followed a similar trend where 2-ODA emerged as the most active compound, with 20 times less potency. The general toxicity and hepatotoxicity of 2-AFAs were evaluated by in vitro and in vivo methods in mammalian cell lines and zebrafish models, respectively. This study identifies 2-ODA as the most promising antiparasitic 2-AFA, particularly towards P. berghei parasites.

Description: More than a decade since the estimation of global subducting sediment (GLOSS), an expanding inductively coupled plasma mass spectrometry dataset for trace elements motivates a new assessment of the bulk sediment flux into deep-sea trenches and an update, GLOSS-II. The specific focus here is on key elements in solid earth recycling that are now better constrained by new data: Li, Be, B, Nb, Ta, Pb, Th, and U. The abundances of these elements reflect, to first order, dilution of continental detritus by biogenic opal and carbonate and, second, various continental and marine processes, such as the extent of continental weathering (Li/K 2 O), hydrogenous versus hydrothermal oxides (Pb/Fe), biophosphate accumulation and exposure age on the seafloor (Th and U), and organic carbon burial (U). The Be/K 2 O ratio (0.86 ± 0.04) and Nb/Ta ratio (14 ± 1) of terrigenous marine sediments reflect average upper continental crust and indeed refine those estimates. Given these new systematics, along with newly published data, revised bulk sediment compositions are calculated for 16 of the 25 trenches included in GLOSS. Two major additional margins are newly assessed (New Zealand-Hikurangi and Chile). Many element budgets are substantially revised for individual trenches, particularly Rb, Cs, Nb, and Pb. A new global weighted average, GLOSS-II, is similar to GLOSS (within 10% relative abundance) for many elements, with more significant changes (up to 50%) in Rb, Cs, Rb/Sr, Nd/Hf, and U/Th. The updated trench estimates provide new insights into sediment recycling at subduction zones, particularly for Li, Be, and Nb. The mass flux of Li subducted into different trenches correlates strongly with the Li/Y ratio in adjacent volcanic arcs, pointing to a direct control on Li enrichment in arcs by subducted sediment. Such a control may be consistent with Li-isotope variations in some arcs, with little fractionation required in the slab or mantle. On the other hand, arcs do not reflect the common Be/K 2 O ratio of most sediments and show fractionation to higher and lower ratios. These fractionations may relate to the different thermal structure of different slabs and/or subducted sediment versus basalt contributions. Sediments vary significantly in their Nb anomaly (i.e., Nb depletion with respect to La and Th), and some arcs inherit the sedimentary Nb anomaly (e.g., South Sandwich) with no new fractionation in the subduction zone, while others (e.g., Marianas and Aleutians) likely require residual rutile in the slab. The Nb anomaly is thus a nearly ubiquitous feature in arcs that has a complex origin, dependent on at least three variables: the sedimentary Nb anomaly, the presence of rutile in the slab (likely driven by Fe 2 + , Fe 3 + , and/or Ti abundances in the sediments), and Nb/La variation in the mantle. Trench sediments and GLOSS-II should thus continue to be useful in elucidating processes occurring in subduction zones, the continents, and the mantle.

Description: Mantle plume behavior near subducting plates is still poorly understood and in fact varies significantly from the classical hotspot model. We investigate using 3D laboratory models how subduction-driven flow relates to the deformation and dispersal of a nearby plume. Results show slab-driven flow severely distorts plume-driven flow, entraining and passively advecting plume material despite its thermal buoyancy. Downdip sinking of the slab initially stalls vertical plume ascent while the combination of downdip and rollback sinking motions redistribute material throughout the system. As a consequence of the subduction-induced flow, surface expressions differ significantly from traditional plume expectations. Variations in slab sinking style and plume position lead to a range in head and conduit melting signatures, as well as migrating hotspots. For the Samoa–Tonga system, model predictions are consistent with proposed entrainment of plume material around the subducting plate.

Description: In North Iceland, extensional plate motion is accommodated by the Northern Volcanic Zone, a set of en-echelon volcanic systems, and the Tjörnes Fracture Zone, a transform offset in the mid-Atlantic Ridge consisting of two parallel transform lineaments. The southern lineament, the Húsavík–Flatey fault, is a 100 km-long right-lateral strike slip fault that has not ruptured for more than 140 years and poses a significant seismic hazard to Húsavík, a fishing town located by the fault, and to other coastal communities. We present results of InSAR time-series analysis data spanning almost two decades (1992–2009) that show extensional and interseismic deformation within the Northern Volcanic Zone and the on-shore part of the Tjörnes Fracture Zone. The results also exhibit transient inflation at Theistareykir volcano, deflation at Krafla central volcano and a broad uplift north of Krafla. The current plate extension is not uniform across the Northern Volcanic Zone, but concentrated at the western fissures of the Theistareykir volcanic system and the outermost fissures of the Krafla fissure swarm. We combine a back-slip plate boundary model with a set of point pressure sources representing volcanic changes to describe the current extensional plate boundary deformation and update the previous estimations of the locking depth and slip rate of the Húsavík–Flatey fault that were based on GPS data alone. Using different combinations of input data, we find that the Húsavík–Flatey fault has a locking depth of 6–10 km and, with a slip rate of 6–9 mm/yr, is accommodating about a third of the full transform motion. We furthermore show that while the InSAR data provide important constraints on the volcanic deformation within the NVZ, they do not significantly improve the model parameter estimation for the HFF, as the dense GPS network appears to better capture the deformation across the fault.

Description: Large scale CO2 storage has previously been considered for the Vedsted structure located in the Northern part of Jylland in Denmark. Pressure buildup in the Gassum reservoir and transmission to the shallower Chalk Group where the brine–fresh water interface resides need to be investigated as part of site qualification, as overpressure can push brine into the fresh water zone and thereby affecting aquifer performance. Pressure transmission from the reservoir into the surrounding formations, when fractures and faults are ignored, will depend on the properties and thickness of the sealing rock. The most important property to be considered is caprock compressibility and permeability. Laboratory experiments on centimeter-scale plugs and dynamic sonic velocity data from relevant shale formations in Denmark indicate that shale compressibility is lower than often assumed for reservoir simulation studies. The measured compressibility for the Fjerritslev Formation is 0.5 × 10−5 bar−1, which is an order of magnitude lower than the standard compressibility (4.5 × 10−5 bar−1) normally used for reservoir simulation studies. The consequences of this lower compressibility are investigated in a simulation case study and the results indicate that higher overpressure is created in the reservoir and the caprock. Overestimating caprock compressibility can therefore underestimate overpressure within the storage and sealing formations and this can have significant implication in the presence of highly permeable fractures and faults. The caprock permeability is measured on core samples using a geotechnical method of constant rate of strain (CRS) experiments which seem to match the modeled permeability data for the Fjerritslev Formation. We found an average vertical permeability of 0.1 μD for the Fjerritslev Formation from the samples measured. The sensitivity of pressure development for the caprock permeability has been studied by varying from one to three orders of magnitude higher and one to two orders of magnitude lower than the measured permeability of 0.1 μD. Injecting 60 million tons (Mt) of CO2 at a rate of 1.5 Mt/year into the Gassum Formation for 40 years indicates that, with permeability above 1.0 μD, overpressure can be transmitted through the 530 m thick Fjerritslev Formation caprock and further up into the overburden layers.

Description: The Richat dome is a spectacular circular structure located in the Mauritanian part of the Sahara Desert. The current erosion level of this igneous complex presents a wide variety of contrasting extrusive and intrusive rocks from shallow to deep source regions providing insight into the magmatic process at the origin of the complex. The Richat is the superposition of a bimodal tholeiitic suite crosscut by carbonatitic and kimberlitic magmatic rocks. The bimodal series is characterized by two concentric gabbroic ring dikes and two extrusive rhyolitic centers representing the remnant of two maar systems. Silica undersaturated magmas occur as carbonatite dikes, a kimberlite plug, and kimberlite sills extruded along the old regional anisotropies filling NNE–SSW dextral strike-slip faults and en-echelon tension gashes. An intense low-temperature hydrothermal event affected the Richat area. It is responsible, notably, for the karst-collapse central mega-breccia, the alteration of the rhyolites, the potassic alteration of the gabbros and the stable isotope enrichment in the carbonatites. A piston-like collapse is proposed to explain the contrast existing between the central and outer part of the Richat. Structural inheritance played an important role in the history of the Richat complex. Pre-existing anisotropies acted as a pathway for the ascent of asthenospheric and sub-continental melts and allowed the coexistence of alkaline and tholeiitic magmas within the same igneous complex.

Description: Chemical examination of the fermentation broth of the marine-derived bacterium Bacillus sp. resulted in the isolation of seven new amicoumacin-type isocoumarin derivatives, namely bacillcoumacins A–G (1–7), together with four known analogues. Their structures were elucidated on the basis of extensive spectroscopic analysis, while the absolute configurations of the new compounds were determined by CD, Mosher’s method, and chemical conversion. Compounds 7 and 9 showed inhibitory effects against the NO production induced by lipopolysaccharide (LPS) in mouse macrophage RAW 264.7 cells.

Description: Previously, carnosic acid and carnosol have demonstrated anti-proliferative activity against different types of cancer. To obtain extracts enriched in these two key phenolic compounds, two different processes have been developed in the present work based on the use of two-step sequential supercritical fluid extraction (SFE). By removing the interfering, less active fractions in a first step (150 or 300 bar, 40°C, neat CO2, 60 min), suitable enrichment is achieved in the second step (150 bar, 40°C, CO2 + 7% ethanol, 120 min), and this leads to carnosic acid concentrations in the extract as high as 40% of total dry weight, which are among the highest concentrations that have been described with this type of process. The enriched extracts were tested against the HT-29 human adenocarcinoma cell line, showing enhancement of their antiproliferative activity by approximately 3-fold compared to previously reported SFE rosemary extracts and higher inhibitory effects at lower concentrations (30 µg mL−1 of extract). Thus, the proposed two-step SFE process effectively improves the carnosic acid and carnosol recovery in shorter processing times (180 min vs. 300 min). Moreover, the obtained extracts possess higher anti-proliferative activity and consume less solvent.

Description: The stratigraphic section “Kellwasser-Tal” is the type locality of the Late Devonian Kellwasser Horizons. The locality, which was already badly preserved shortly after its discovery in the middle of the 19 th century by F.A. Roemer, has recently been re-opened and widened. The newly created section ranges from the upper Frasnian to the Lower Carboniferous “Kulm-Kieselschiefer”. Although some parts of the outcrop are highly tectonised it is nonetheless possible to reconstruct the sedimentary sequence. The Kellwasser Horizons, connected to one of the five most severe mass-extinction events in Earth History (Kellwasser Crisis), can now be studied again in detail. Conodonts sampled by O.H. Walliser (Göttingen) in the 1980s as well as new samples were investigated with respect to conodont biostratigraphy and microfacies. The type locality is situated in the European Geopark Harz-Braunschweiger Land-Ostfalen and should be protected as a geosite. Das Profil Kellwasser-Tal (NW-Harz) ist die Typlokalität der oberdevonischen Kellwasser-Horizonte. Die Lokalität, schon bald nach ihrer Entdeckung durch F.A. Roemer Mitte des 19. Jahrhunderts verfallen, ist maschinell erneut freigelegt worden. Es liegt nun ein zusammenhängendes Profil vom höheren Frasnium bis in die Kulm-Kieselschiefer des Unterkarbons vor. Obwohl Teile des Aufschlusses tektonisch sehr stark beansprucht sind, ist die Rekonstruktion der sedimentären Abfolge möglich. Die beiden Kellwasser-Horizonte, zwei isochrone, global nachweisbare Litho-Einheiten (,,Kellwasser-Kalke“), sind wieder gut aufgeschlossen. Sie bezeugen eines der fünf größten Aussterbe-Ereignisse der Erdgeschichte (Kellwasser-Krise). Im Zusammenhang mit den Geländeaktivitäten ist Sammlungsmaterial (Conodontenfaunen, An- und Dünnschliffe) aufgearbeitet worden, so dass der gegenwärtige Bearbeitungsstand der Lokalität dargestellt werden kann. Grundlage der stratigrafischen Bearbeitung waren insbesondere Conodontenproben, welche unter Leitung von O.H. Walliser (Göttingen) in den 1980er Jahren gesammelt wurden. Zusätzliches, in den letzten Jahren entnommenes Material (Conodonten- und sedimentologisch-fazielle Proben) ließ sich mit den Banknummern von Walliser korrelieren. Diese Typlokalität ist Teil des Europäischen Geoparks Harz-Braunschweiger Land-Ostfalen und sollte als Geotop geschützt und erhalten bleiben.

Description: Highlights • Naturally enriched AOM biomass was studied in high-pressure continuous incubation. • We report the first S- and O-isotope fractionation values by sulfate reduction coupled to AOM from culture studies. • There is a tight link between methane concentration and S- and O-isotope fractionation. • S- and O-isotope fractionation values indicate reversibility of energy limited microbial processes. • The wide range of environmental S- and O-isotope signatures can be explained. Abstract Isotope signatures of sulfur compounds are key tools for studying sulfur cycling in the modern environment and throughout earth's history. However, for meaningful interpretations, the isotope effects of the processes involved must be known. Sulfate reduction coupled to the anaerobic oxidation of methane (AOM-SR) plays a pivotal role in sedimentary sulfur cycling and is the main process responsible for the consumption of methane in marine sediments − thereby efficiently limiting the escape of this potent greenhouse gas from the seabed to the overlying water column and atmosphere. In contrast to classical dissimilatory sulfate reduction (DSR), where sulfur and oxygen isotope effects have been measured in culture studies and a wide range of isotope effects has been observed, the sulfur and oxygen isotope effects by AOM-SR are unknown. This gap in knowledge severely hampers the interpretation of sulfur cycling in methane-bearing sediments, especially because, unlike DSR which is carried out by a single organism, AOM-SR is presumably catalyzed by consortia of archaea and bacteria that both contribute to the reduction of sulfate to sulfide. We studied sulfur and oxygen isotope effects by AOM-SR at various aqueous methane concentrations from 1.4±0.6 mM1.4±0.6 mM up to 58.8±10.5 mM58.8±10.5 mM in continuous incubation at steady state. Changes in the concentration of methane induced strong changes in sulfur isotope enrichment (View the MathML sourceεS34) and oxygen isotope exchange between water and sulfate relative to sulfate reduction (θOθO), as well as sulfate reduction rates (SRR). Smallest View the MathML sourceεS34 (21.9±1.9‰21.9±1.9‰) and θOθO (0.5±0.20.5±0.2) as well as highest SRR were observed for the highest methane concentration, whereas highest View the MathML sourceεS34 (67.3±26.1‰67.3±26.1‰) and θOθO (2.5±1.52.5±1.5) and lowest SRR were reached at low methane concentration. Our results show that View the MathML sourceεS34, θOθO and SRR during AOM-SR are very sensitive to methane concentration and thus also correlate with energy yield. In sulfate–methane transition zones, AOM-SR is likely to induce very large sulfur isotope fractionation between sulfate and sulfide (i.e. 〉60‰〉60‰) and will drive the oxygen isotope composition of sulfate towards the sulfate–water oxygen isotope equilibrium value. Sulfur isotope fractionation by AOM-SR at gas seeps, where methane fluxes are high, will be much smaller (i.e. 20 to 40‰).

Description: Late Pliocene changes in the advection of Mediterranean Outflow Water (MOW) derivates were reconstructed at northeast Atlantic DSDP/ODP sites 548 and 982 and compared to records of WMDW at West Mediterranean Site 978. Neodymium isotope (εNd) values more positive than −10.5/−11 reflect diluted MOW derivates that spread almost continuously into the northeast Atlantic from 3.7 to 2.55 Ma, reaching Rockall Plateau Site 982 from 3.63 to 2.75 Ma. From 3.4 to 3.3 Ma average MOW temperature and salinity increased by 2°–4 °C and ~1 psu both at proximal Site 548 and distal Site 982. The rise implies a rise in flow strength, coeval with a long-term rise in both west Mediterranean Sea surface salinity by almost 2 psu and average bottom water salinity (BWS) by ~1 psu, despite inherent uncertainties in BWS estimates. The changes were linked with major Mediterranean aridification and a drop in African monsoon humidity. In contrast to model expectations, the rise in MOW salt discharge after 3.4 Ma did not translate into improved ventilation of North Atlantic Deep Water, since it possibly was too small to significantly influence Atlantic Meridional Overturning Circulation. Right after ~2.95 Ma, with the onset of major Northern Hemisphere Glaciation, long-term average bottom water temperature (BWT) and BWS at Site 548 dropped abruptly by ~5 °C and ~1–2 psu, in contrast to more distal Site 982, where BWT and BWS continued to oscillate at estimates of ~2 °C and 1.5–2.5 psu higher than today until ~2.6 Ma. We relate the small-scale changes both to a reduced MOW flow and to enhanced dilution by warmwaters of a strengthenedNorth Atlantic Current temporarily replacingMOWderivates at Rockall Plateau.

Description: Noble gas radionuclides, including 81Kr (t1/2 = 229,000 years), 85Kr (t1/2 = 10.8 years), and 39Ar (t1/2 = 269 years), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide. We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically: determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times. Other scientific questions involving a deeper circulation of fluids in the Earth's crust and mantle are also within the scope of future applications. We conclude that the geoscience community would greatly benefit from an ATTA facility dedicated to this field, with instrumentation for routine measurements, as well as for research on further development of ATTA methods.

Description: Abstract Ethnopharmacological relevance The oil macerates of Hypericum perforatum L. (St. John׳s Wort=SJW) have a long history of medicinal use and SJW has been used in traditional medicine both orally and topically for centuries worldwide mainly for wound healing, ulcer and inflammation. Materials and methods We analyzed the fatty acid composition of 10 traditionally (home-made) and 13 commercially (ready-made) prepared SJW oil macerates by GC–MS. The acid, peroxide, iodine, saponification values, and the unsaponifiable matters of the samples were determined according to the European Pharmacopoeia. We also explored potential mechanism of wound healing effect of the samples, i.e. TNFα-induced NF-κB activation. Results The most home-made oil samples contained oleic acid predominantly and complied with the requirements set for olive oil by European Pharmacopoeia. However, majority of the ready-made samples appeared to have adulteration with some other oils. Moderate NF-κB inhibitory effects have been observed with some of the oil samples. Conclusion This study sheds light on the fact that application of the proper traditional method to prepare olive oil macerates from Hypericum perforatum is able to get bioactive constituents in the oil. Besides, inhibition of TNFα-induced NF-κB activation appears to be a potential mechanism for topical wound healing activity of SJW oil macerates.

Description: Highlights: • We coupled LA-ICP-MS Me/Ca single-chamber composition of four planktonic foraminifera with eddy induced hydrographic changes • The Mg/Ca-based temperature difference between N. dutertrei and G. scitula are likely to be an eddy proxy suitable for down-core application • Near-surface dwelling species inhabit well oxygenated surface waters and show lower test Mn/Ca values, compared to deeper dwelling species • Planktonic foraminifera Mn/Ca test values are in line with water column variability in dissolved Mn concentrations Hydrographic conditions in the Mozambique Channel are dominated by the passing of large anticyclonic eddies, propagating poleward into the upstream Agulhas area. Further south, these eddies have been found to control the shedding of Agulhas rings into the Atlantic ocean, thereby playing a key role in Indo-Atlantic Ocean exchange. The element composition of several planktonic foraminifera species collected from sediment trap samples, was compared to in situ water column data from the Mozambique Channel. Single-chamber trace element composition of these foraminifera reveals a close coupling with hydrographic changes induced by anticyclonic eddies. Obtained Mg/Ca values for the surface dwelling Globigerinoides ruber as well as the thermocline dwelling Neogloboquadrina dutertrei follow temperature changes and reduced temperature stratification during eddy conditions. At greater depth. Globorotalia scitula and Pulleniatina obliquiloculata record stable temperatures and thus respond to hydrographic changes with a deepening in habitat depth. Furthermore, test Mn/Ca values indicate a close relationship between water column oxygenation and Mn incorporation in these planktonic foraminiferal species

Description: The recent marine carbonate world comprises two major compartments: (1) the surface domain of the photozoan carbonates, confined in space by water depth and by the penetration of light, and (2) a deep domain, where heterozoan mound-builder guilds directly forage on fluxes of nutrients, which primarily percolate from the photic zone and/or are generated by in situ benthic processes. Locally, giant cold-water coral mounds tower up to heights of 150 to 250 m above the sea floor, in general between 500 and 1300 m water depth and within sharply delineated provinces. Some 15 years of research on these giant mound provinces conveys a picture of their distribution in space and possibly sheds light on controls, acting in concert. Globally, there is no counterpart for the prolific North Atlantic Mound Basin (NAMB). A chemical control is seen by an overlay of the mound provinces on a map of the aragonite saturation horizon (ASH). An external physical control is inferred fromthe position of themound provinces, girdling a vigorous North Atlantic subtropical gyre systemand clustering close to the roof of the intermediate to deep water masses of a dynamically stratified ocean. On the eastern boundary of the NAMB, nutrient fluxes are enhanced by mixing processes, driven either by internal waves between Galicia and the Shetlands, or by the vast and heterogeneous Eastern Boundary Upwelling System along the Iberian/African margins down to 10°N. Early diagenesis by carbonate dissolution and re-precipitation driven by convecting or advecting internal fluids can contribute to stabilize such constructions, facilitating an exuberant vertical accretion. It is speculated that in theNorth Atlantic Ocean, the deep-water carbonate factory outclasses in size the shallow water coral reefs. Giant mound formation is a recurrent play of Life since the dawn of the metazoans (Nama Group, Upper Neoproterozoic), however with actors and plots, varying from act to act. Remarkably, literature reports only three occurrences of deep-water mounds in the Phanerozoic: the modern ocean, possibly the Danian, and the Carboniferous. Some striking parallelisms in the development of the Atlantic and the Paleo-Tethys oceans, combined with the developing insights in the controls on deep-watermounds in the present ocean, invite for a comparative study. This has the potential to eventually shed light on the full circulation pattern of the Paleo-Tethys Ocean, surface and deep. Comparative studies will build upon (1) modeling of ocean circulation constrained by the record of deep-water carbonate systems and supported by advances in tracer and proxy tools, and (2) field studies on representative and accessible continental locations. The mound route that develops in Morocco under the auspices of IOC-UNESCO will provide tomulti-disciplinary teams with marine and continental experience opportunities for confronting observations from the modern ocean and on key records of past oceanic basins. It has the potential to eventually qualify for a UNESCO recognition as World Heritage.

Description: Due to the strong interest in geochemical CO2-fluid-rock interaction in the context of geological storage of CO2 a growing number of research groups have used a variety of different experimental ways to identify important geochemical dissolution or precipitation reactions and – if possible – quantify the rates and extent of mineral or rock alteration. In this inter-laboratory comparison the gas-fluid-mineral reactions of three samples of rock-forming minerals have been investigated by 11 experimental labs. The reported results point to robust identification of the major processes in the experiments by most groups. The dissolution rates derived from the changes in composition of the aqueous phase are consistent overall, but the variation could be reduced by using similar corrections for changing parameters in the reaction cells over time. The comparison of experimental setups and procedures as well as of data corrections identified potential improvements for future gas-fluid-rock studies.

Description: Supercritical carbon dioxide (SC-CO2) extraction of lipid from Scenedesmus sp. for biodiesel production was investigated and compared to conventional extraction methods. The effect of biomass pre-treatment prior to extraction and extracting conditions, namely pressure in the range of 200–500 bar, temperatures in the range of 35–65 °C and CO2 flow rate in the range of 1.38–4.02 g min−1, on SC-CO2 extraction yield and quality of lipid were investigated. Three levels full factorial design of experiments and response surface methodology was used to model the system. A second order polynomial model was developed and used to predict the optimum conditions. Scaling up to a laboratory larger scale was also tested. The results indicated that SC-CO2 extraction was superior to other extraction techniques, but exhibited significant variations in yield with changes in operating parameters. In the developed model, it was found that the linear and quadratic terms of the temperature, as well as the interaction with pressure had a significant effect on lipid yield; whereas, their effect on lipid quality was insignificant. The best operating conditions, in the tested range, were 53 °C, 500 bar and 1.9 g min−1, in which lipid extraction yield of 7.41% (dry weight basis) was obtained. Negligible differences were observed when the fatty acid composition of SC-CO2 extracted lipid was compared to that extracted by the conventional methods. At the optimum conditions, SC-CO2 extraction was successfully scaled-up by eight-folds and the extracted lipid yield dropped by 16%.

Description: Decades of paleoceanographic studies have reconstructed a well-resolved water mass structure for the deep Atlantic Ocean during the Last Glacial Maximum (LGM). However, the variability of intermediate water circulation in the tropics over the LGM and deglacial abrupt climate events is still largely debated. This study aims to reconstruct intermediate northern- and southern-sourced water circulation in the tropical North Atlantic during the past 22 kyr and attempts to confine the boundary between Antarctic Intermediate Water (AAIW) and northern-sourced intermediate water (i.e., upper North Atlantic Deep Water (NADW) or Glacial North Atlantic Intermediate Water) in the past. High-resolution Nd isotopic compositions of fish debris and acid-reductive leachate of bulk sediment in core VM12-107 (1079 m depth) from the Southern Caribbean are not in agreement. We suggest that the leachate method does not reliably extract the Nd isotopic compositions of seawater at this location, and that it needs to be tested in more detail in various oceanic settings. The fish debris εNd values display a general decrease from the early deglaciation to the end of the Younger Dryas, followed by a greater drop toward less radiogenic values into the early Holocene. We propose a potentially more radiogenic glacial northern endmember water mass and interpret this pattern as recording a recovery of the upper NADW during the last deglaciation. Comparing our new fish debris Nd isotope data to authigenic Nd isotope studies in the Florida Straits (546 and 751 m depth), we propose that both glacial and deglacial AAIW do not penetrate beyond the lower depth limit of modern AAIW in the tropical Atlantic.

Description: Highlights • Numerical simulations to investigate climate change impact on estuarine circulation. • Rising sea levels lead to stronger UGC and enhanced salinity intrusion. • With low inflows, effects of sea-level rise on salinity intrusion are largest. • Stronger inflows required with sea-level rise to maintain L in San Francisco Bay. Abstract Estuaries lie at the interface of land and sea, and are particularly vulnerable to sea-level rise due to climate change that might lead to intrusion of salt water further upstream and affect circulation patterns. Climate change is also likely to have a major impact on hydrological cycles and consequently lead to changes in freshwater inflows into estuaries. An idealized estuary model is employed to investigate the effects of sea-level rise and freshwater inflows on estuarine circulation. Rising sea levels result in a stronger longitudinal salinity gradient ∂s/∂x, indicating an increase in the strength of the gravitational circulation UGC, higher longitudinal dispersion coefficients K and enhanced salinity intrusion. Under low-flow conditions, the effects of sea level rise on salinity intrusion are largest because sea-level rise has a greater impact due to weaker vertical stratification. Strong flows increase the strength of the gravitational circulation, resulting in higher vertical stratification, which leads to the nonlinear feedback between vertical mixing and stratification. The effect of sea-level rise on salinity intrusion is reduced owing to the suppression of mixing by stratification. Supporting three-dimensional simulations from northern San Francisco Bay are presented. The intrusion length scale L is used as a substitute for regulating inflows to ensure that sufficient fresh water is available to flush the Bay. Following a set of standards explicitly stated in the 1994 Bay-Delta Accord, a series of simulations is performed and we find that with sea-level rise stronger inflows are required to maintain L at the proposed locations.

Description: We present new Sr-Nd-Pb-Hf-O isotope data from the volcanic arc (VA, volcanic front and rear arc) in Chile and the backarc (BA) in Argentina of the Central Southern Volcanic Zone in Chile (CSVZ; 38-43°S). Compared to the Transitional (T) SVZ (34.5-38°S; Jacques et al., 2013), the CSVZ VA has erupted greater volumes over shorter time intervals (Völker et al., 2011) and produced more tholeiitic melts. Although the CSVZ VA monogenetic cones are similar to the TSVZ VA samples, the CSVZ VA stratovolcanoes have higher ratios of highly fluid-mobile to less fluid-mobile trace elements (e.g. U/Th, Pb/Ce, Ba/Nb) and lower more- to less-incompatible fluid-immobile element ratios (e.g. La/Yb, La/Sm, Th/Yb, Nb/Yb), consistent with an overall higher fluid flux and greater degree of flux melting beneath the CSVZ stratovolcanoes compared to the CSVZ monogenetic centers and the TSVZ VA. The CSVZ monogenetic centers overlap the TSVZ in Sr and Nd isotopes, but the stratovolcanoes are shifted to higher Sr and/or Nd isotope ratios. The Pb isotopic composition of the CSVZ overlaps the TSVZ, which is clearly dominated by the composition of the trench sediments, but the CSVZ monogenetic samples extend to less radiogenic Pb isotope ratios. δ18Omelt from the CSVZ stratovolcano samples are below the MORB range, whereas the CSVZ monogenetic and the TSVZ samples fall within and slightly above the MORB range. The Nd and Hf isotopic ratios of the CSVZ VA extend to more radiogenic compositions than found in the TSVZ VA, indicating a greater contribution from a more depleted source. These correlations are interpreted to reflect derivation of fluids from hydrothermally altered oceanic crust and/or serpentinized upper mantle of the subducting plate. CSVZ BA basalts largely overlap TSVZ BA basalts, displaying less or no subduction influence compared to the VA, but some CSVZ BA basalts tap more enriched mantle, possibly subcontinental lithosphere, with distinctively lower Nd and Hf and elevated 207Pb/204Pb and 208Pb/204Pb isotope ratios.

Description: This chapter has four main aims. Provide a comprehensive picture of the composition of volcanic rocks from subduction-related magmatic arcs. Review evidence in favor of the existence of andesitic, as well as basaltic primary magmas in arcs. Present new data on the composition of arc lower crust, based mainly on our work on the Talkeetna arc section in southcentral Alaska. Summarize evidence from arc lower crustal sections that a substantial proportion of the dense, lower crustal pyroxenites and garnet granulites produced by crystal fractionation are missing.

Description: Highlights: • Modeling of oxygen conditions of the Baltic Sea for the period 1970–2010 by a coupled hydrodynamic-oxygen consumption model • Determination of the evolution of hypoxic and anoxic areas for the period 1970–2010 for the total Baltic Sea • Determination of the frequencies of the occurrences of areas of oxygen deficiencies for the period 1970–2010 • Calculation of the Baltic Cod reproduction volumes in the Bornholm Basin for the period 1970–2010 Abstract: The Baltic Sea deep waters suffer from extended areas of hypoxia and anoxia. Their intra- and inter-annual variability is mainly determined by saline inflows which transport oxygenated water to deeper layers. During the last decades, oxygen conditions in the Baltic Sea have generally worsened and thus, the extent of hypoxic as well as anoxic bottom water has increased considerably. Climate change may further increase hypoxia due to changes in the atmospheric forcing conditions resulting in less deep water renewal Baltic inflows, decreased oxygen solubility and increased respiration rates. Feedback from climate change can amplify effects from eutrophication. A decline in oxygen conditions has generally a negative impact on marine life in the Baltic Sea. Thus, a detailed description of the evolution of oxygenated, hypoxic and anoxic areas is particularly required when studying oxygen-related processes such as habitat utilization of spawning fish, survival rates of their eggs as well as settlement probability of juveniles. One of today's major challenges is still the modeling of deep water dissolved oxygen, especially for the Baltic Sea with its seasonal and quasi-permanent extended areas of oxygen deficiency. The detailed spatial and temporal evolution of the oxygen concentrations in the entire Baltic Sea have been simulated for the period 1970–2010 by utilizing a hydrodynamic Baltic Sea model coupled to a simple pelagic and benthic oxygen consumption model. Model results are in very good agreement with CTD/O2-profiles taken in different areas of the Baltic Sea. The model proved to be a useful tool to describe the detailed evolution of oxygenated, hypoxic and anoxic areas in the entire Baltic Sea. Model results are further applied to determine frequencies of the occurrence of areas of oxygen deficiency and cod reproduction volumes.

Description: Despite its enormous extent and importance for global climate, the South Pacific has been poorly investigated in comparison to other regions with respect to chemical oceanography. Here we present the first detailed analysis of dissolved radiogenic Nd isotopes (εNd) and rare earth elements (REEs) in intermediate and deep waters of the mid-latitude (∼40°S) South Pacific along a meridional transect between South America and New Zealand. The goal of our study is to gain better insight into the distribution and mixing of water masses in the South Pacific and to evaluate the validity of Nd isotopes as a water mass tracer in this remote region of the ocean. The results demonstrate that biogeochemical cycling (scavenging processes in the Eastern Equatorial Pacific) and release of LREEs from the sediment clearly influence the distribution of the dissolved REE concentrations at certain locations. Nevertheless, the Nd isotope signatures clearly trace water masses including AAIW (Antarctic Intermediate Water) (average εNd = −8.2 ± 0.3), LCDW (Lower Circumpolar Deep Water) (average εNd = −8.3 ± 0.3), NPDW (North Pacific Deep Water) (average εNd = −5.9 ± 0.3), and the remnants of NADW (North Atlantic Deep Water) (average εNd = −9.7 ± 0.3). Filtered water samples taken from the sediment–water interface under the deep western boundary current off New Zealand suggest that boundary exchange processes are limited at this location and highlight the spatial and temporal variability of this process. These data will serve as a basis for the paleoceanographic application of Nd isotopes in the South Pacific.

Description: Numerous calcium carbonate veins were recovered from the igneous basement of the Early Cretaceous Shatsky Rise during Integrated Ocean Drilling Program (IODP) Expedition 324. The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, !18O, !13C) compositions of these veins were determined to constrain the timing of vein formation. A dominant control by seawater chemistry on calcite composition is evident for most vein samples with variable contributions fromthe basaltic basement. Slightly elevated precipitation temperatures (as inferred from oxygen isotope ratios), indicative of hydrothermal vein formation, are only observed at Site U1350 in the central part of Shatsky Rise. The highest 87Sr/86Sr ratios (least basement influence) of vein samples at each drill site range from 0.70726 to 0.70755 and are believed to reflect the contemporaneous seawater composition during the time of calcite precipitation. In principle, age information can be deduced by correlating these ratios with the global seawater Sr isotope evolution. Since the Sr isotopic composition of seawater has fluctuated three times between the early and mid Cretaceous, no unambiguous precipitation ages can be constrained by this method and vein precipitation could have occurred at any time between ~80 and 140 Ma. However, based on combined chemical and isotopic data and correlations of vein compositionwith formation depth and inferred temperature, we argue for a rather early precipitation of the veins shortly after basement formation at each respective drill site.

Description: Preprocessing software, which converts large instrumental data sets into a manageable format for data analysis, is crucial for the discovery of chemical signatures in metabolomics, chemical forensics, and other signature-focused disciplines. Here, four freely available and published preprocessing tools known as MetAlign, MZmine, SpectConnect, and XCMS were evaluated for impurity profiling using nominal mass GC/MS data and accurate mass LC/MS data. Both data sets were previously collected from the analysis of replicate samples from multiple stocks of a nerve-agent precursor and method blanks. Parameters were optimized for each of the four tools for the untargeted detection, matching, and cataloging of chromatographic peaks from impurities present in the stock samples. The peak table generated by each preprocessing tool was analyzed to determine the number of impurity components detected in all replicate samples per stock and absent in the method blanks. A cumulative set of impurity components was then generated using all available peak tables and used as a reference to calculate the percent of component detections for each tool, in which 100% indicated the detection of every known component present in a stock. For the nominal mass GC/MS data, MetAlign had the most component detections followed by MZmine, SpectConnect, and XCMS with detection percentages of 83, 60, 47, and 41%, respectively. For the accurate mass LC/MS data, the order was MetAlign, XCMS, and MZmine with detection percentages of 80, 45, and 35%, respectively. SpectConnect did not function for the accurate mass LC/MS data. Larger detection percentages were obtained by combining the top performer with at least one of the other tools such as 96% by combining MetAlign with MZmine for the GC/MS data and 93% by combining MetAlign with XCMS for the LC/MS data. In terms of quantitative performance, the reported peak intensities from each tool had averaged absolute biases (relative to peak intensities obtained using instrument software) of 41, 4.4, 1.3 and 1.3% for SpectConnect, MetAlign, XCMS, and MZmine, respectively, for the GC/MS data. For the LC/MS data, the averaged absolute biases were 22, 4.5, and 3.1% for MetAlign, MZmine, and XCMS, respectively. In summary, MetAlign performed the best in terms of the number of component detections; however, more than one preprocessing tool should be considered to avoid missing impurities or other trace components as potential chemical signatures.

Description: Cold-water coral communities cover a wide range of possible habitats in terms of latitude, ocean basins, and depth, with ongoing studies continually expanding occurrences in various regions of the global ocean. A range of factors determines the formation of cold-water coral reefs, such as physical, hydrochemical, and biological (e.g. food supply) factors. Recently, more and more modeling studies have emerged using a variety of mathematical approaches have emerged including environmental niche factor analysis (ENFA) and predictive habitat suitability models. However, only few studies have attempted to characterize the underlying suite of hydro-biogeochemical and physical constraints of cold-water coral reefs and to differentiate between pristine reef growth vs. sites with reduced or no coral occurrences. This study concentrates on new data and a compilation of existing data sets on the physical and chemical properties in the NE Atlantic and the Mediterranean. It explores the influence of ambient bottom waters and its characteristics on living cold-water reefs and mounds formed by Lophelia pertusa. Several questions are addressed: (1) what are the physical and geochemical boundary conditions of living cold-water corals? (2) Do these geochemical parameters correlate with proposed physical prerequisites? (3) Is there a general difference in the signature of living and dead coral sites?

Description: Tidal processes play an important role in the dynamics of shelf circulation in the Laptev Sea. The Unstructured Grid Finite Volume Coastal Ocean Model (FVCOM) is used to simulate the tidal dynamics in the Lena Delta region of the Laptev Sea in ice-free barotropic case. The grid element size ranges from 400 m to 5 km. The major semidiurnal tidal waves M2M2 and S2S2 are investigated with the M2M2 being the most important in generating large sea level amplitudes and currents over shallow areas. A correction to the tidal elevation at the open boundary is proposed, which minimizes the discrepancy between the model prediction and observations. The observations include both recent mooring data and the standard set of tide gauge measurements used in previous studies. The comparison of results to known tidal solutions is carried out. The paper also discusses the residual circulation and energy fluxes and assesses the impact of additional bathymetric information. Highlights • Our simulations reproduce the semidiurnal tidal waves M2M2 and S2S2 in the Laptev Sea region. • We develop special procedure for the construction of optimal open boundary conditions for tidal elevation for M2M2 and S2S2 constituents. • The simulated tidal maps show an improved agreement with observations. • We analyze barotropic currents, residual circulation and evolution of energy fluxes in the region. • We consider the energy balance for the M2M2 and S2S2 waves and the sensitivity to the bathymetry.

Description: Mineral assemblage, trace element content and Nd and Pb isotope signatures were analysed on the fine fraction (〈20 μm) of sedimentary records from the Northern Mendeleev Ridge in the Central Arctic Ocean. Our aim was to identify the detrital particle provenance and to interpret the changes over the past ∼250 ka in the relative contribution of the different source-areas in relation to paleoenvironmental conditions. The clay mineral assemblage and the Nd and Pb isotope signatures depict systematic changes over the Late Quaternary. The bulk mineralogy exhibits increases in the relative contribution of carbonate minerals vs. silicates in interglacial/deglacial intervals. In glacial intervals, the mineral assemblage of the 〈20 μm fraction is characterised by an enrichment in kaolinite, counterbalanced by a decrease in illite. The Nd and Pb isotope signatures of 〈20 μm fraction are interpreted using a three end-member mixing model, involving crustal supplies from North America and Canada, from the Siberian margin and some from volcanic material. A compilation of geochemical signatures of geological terraines surrounding the Arctic Ocean allowed each end-member to be assigned a representative signature, averaging the signal of the eroded terraines. The Suspended Particulate Matter (SPM) of the MacKenzie River represents an average signature of the sedimentary supplies delivered from the North American platform and Canadian margin. The SPM of the Lena River reflects the mean sedimentary signature of the Siberian platform. The Okhotsh-Chukotka province from the Eastern border of Siberia is identified as the most probable volcanic source. Late Quaternary evolution of the estimated relative contribution of the three end-members confirms that the sediment provenances in the Central Arctic Ocean remain close to the current conditions during past interglacials/deglacials MIS1–3, MIS5/TII and MIS7/TIII. In contrast, glacial conditions (MIS4 and MIS6) record minimum supplies from the American margin, associated with increased volcanic contribution, to the Mendeleev Ridge core location suggesting a different sea-ice circulation associated with a low sea-level and reduced shelf area. Highlights • Nd and Pb isotope signatures of fine detrital sediment fraction are tracer of sources. • Glacial and interglacials are characterised by systematic changes in sediment sources. • The volcanic Okhotsh-Chukotka province has major contribution during glacials.

Description: Deep-sea benthic communities and their structural and functional characteristics are regulated by surface water processes. Our study focused on the impact of changes in water depth and food supplies on small-sized metazoan bottom-fauna (meiobenthos) along a bathymetric transect (1200–5500 m) in the western Fram Strait. The samples were collected every summer season from 2005 to 2009 within the scope of the HAUSGARTEN monitoring program. In comparison to other polar regions, the large inflow of organic matter to the sea floor translates into relatively high meiofaunal densities in this region. Densities along the bathymetric gradient range from approximately 2400 ind. 10 cm-2 at 1200 m to approximately 300 ind. 10 cm-2 at 4000 m. Differences in meiofaunal distribution among sediment layers (i.e., vertical profile) were stronger than among stations (i.e., bathymetric gradient). At all the stations meiofaunal densities and number of taxa were the highest in the surface sediment layer (0–1 cm), and these decreased with increasing sediment depth (down to 4–5 cm). However, the shape of the decreasing pattern differed significantly among stations. Meiofaunal densities and taxonomic richness decreased gradually with increasing sediment depth at the shallower stations with higher food availability. At deeper stations, where the availability of organic matter is generally lower, meiofaunal densities decreased sharply to minor proportions at sediment depths already at 2–3 cm. Nematodes were the most abundant organisms (60–98%) in all the sediment layers. The environmental factors best correlated to the vertical patterns of the meiofaunal community were sediment-bound chloroplastic pigments that indicate phytodetrital matter. Highlights • Small-scale heterogeneity is the main source of variation in meiofauna community. • Trophic conditions influence vertical patterns of meiofauna distribution. • Meiofauna abundance and biomass decrease with increasing water depth.

Description: TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) is a sea surface temperature (SST) proxy based on the distribution of archaeal isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs). In this study, we appraise the applicability of TEX86 and View the MathML sourceTEX86L in subpolar and polar regions using surface sediments. We present TEX86 and View the MathML sourceTEX86L data from 160 surface sediment samples collected in the Arctic, the Southern Ocean and the North Pacific. Most of the SST estimates derived from both TEX86 and View the MathML sourceTEX86L are anomalously high in the Arctic, especially in the vicinity of Siberian river mouths and the sea ice margin, plausibly due to additional archaeal contributions linked to terrigenous input. We found unusual GDGT distributions at five sites in the North Pacific. High GDGT-0/crenarchaeol and GDGT-2/crenarchaeol ratios at these sites suggest a substantial contribution of methanogenic and/or methanotrophic archaea to the sedimentary GDGT pool here. Apart from these anomalous findings, TEX86 and View the MathML sourceTEX86L values in the surface sediments from the Southern Ocean and the North Pacific do usually vary with overlaying SSTs. In these regions, the sedimentary TEX86-SST relationship is similar to the global calibration, and the derived temperature estimates agree well with overlaying annual mean SSTs at the sites. However, there is a systematic offset between the regional View the MathML sourceTEX86L-SST relationships and the global calibration. At these sites, temperature estimates based on the global View the MathML sourceTEX86L calibration are closer to summer SSTs than annual mean SSTs. This finding suggests that in these subpolar settings a regional View the MathML sourceTEX86L calibration may be a more suitable equation for temperature reconstruction than the global calibration.

Description: IODP Expedition 307 made it for the first time possible to investigate the entire body of a cold-water coral carbonate mound. Here we provide new insights into the long-term history of Challenger Mound on the European continental margin off Ireland. This study is based on age determinations (230Th/U, 87Sr/86Sr) and geochemical signals (Mg/Li and Ba/Ca) measured in the scleractinian cold-water coral Lophelia pertusa from IODP Site 1317 in the Porcupine Seabight. The paleoceanographic reconstructions reveal that coral growth in the Porcupine Seabight was restricted to specific oceanographic conditions such as enhanced export of primary production and Bottom-Water Temperatures (BWT) between ∼8–10 °C, related to the water mass stratification of the Mediterranean Outflow Water (MOW) and Eastern North Atlantic Water (ENAW). The geochemical signals from the coral skeletons can be explained by the close interaction between cold-water coral growth, sea-surface productivity and the surrounding water masses - the boundary layer between MOW and ENAW. Enhanced sea-surface productivity and the build-up of a stable water mass stratification between ENAW and MOW caused enhanced nutrient supply at intermediate water depths and facilitated a steady mound growth between∼3.0 - 2.1 Ma. With the decrease in sea-surface productivity and related reduced export productivity the food supply was insufficient for rapid coral mound growth between∼1.7 - 1 Ma. During the late Pleistocene (over the last∼0.5 Myr) mound growth was restricted to interglacial periods. During glacials the water mass boundary between ENAW/MOW probably was below the mound summit and hence food supply was not sufficient for corals to grow.

Description: The isotopic composition of Phanerozoic marine sediments provides important information about changes in seawater chemistry. In particular, the radiogenic strontium isotope (87Sr/86Sr) system is a powerful tool for constraining plate tectonic processes and their influence on atmospheric CO2 concentrations. However, the 87Sr/86Sr isotope ratio of seawater is not sensitive to temporal changes in the marine strontium (Sr) output flux, which is primarily controlled by the burial of calcium carbonate (CaCO3) at the ocean floor. The Sr budget of the Phanerozoic ocean, including the associated changes in the amount of CaCO3 burial, is therefore only poorly constrained. Here, we present the first stable isotope record of Sr for Phanerozoic skeletal carbonates, and by inference for Phanerozoic seawater (δ88/86Srsw), which we find to be sensitive to imbalances in the Sr input and output fluxes. This δ88/86Srsw record varies from ∼0.25‰ to ∼0.60‰ (vs. SRM987) with a mean of ∼0.37‰. The fractionation factor between modern seawater and skeletal calcite Δ88/86Srcc-sw, based on the analysis of 13 modern brachiopods (mean δ88/86Sr of 0.176±0.016‰, 2 standard deviations (s.d.)), is -0.21‰ and was found to be independent of species, water temperature, and habitat location. Overall, the Phanerozoic δ88/86Srsw record is positively correlated with the Ca isotope record (δ44/40Casw), but not with the radiogenic Sr isotope record ((87Sr/86Sr)sw). A new numerical modeling approach, which considers both δ88/86Srsw and (87Sr/86Sr)sw, yields improved estimates for Phanerozoic fluxes and concentrations for seawater Sr. The oceanic net carbonate flux of Sr (F(Sr)carb) varied between an output of -4.7x1010mol/Myr and an input of +2.3x1010mol/Myr with a mean of -1.6x1010mol/Myr. On time scales in excess of 100Myrs the F(Sr)carb is proposed to have been controlled by the relative importance of calcium carbonate precipitates during the “aragonite” and “calcite” sea episodes. On time scales less than 20Myrs the F(Sr)carb seems to be controlled by variable combinations of carbonate burial rate, shelf carbonate weathering and recrystallization, ocean acidification, and ocean anoxia. In particular, the Permian/Triassic transition is marked by a prominent positive δ88/86Srsw-peak that reflects a significantly enhanced burial flux of Sr and carbonate, likely driven by bacterial sulfate reduction (BSR) and the related alkalinity production in deeper anoxic waters. We also argue that the residence time of Sr in the Phanerozoic ocean ranged from ∼1Myrs to ∼20Myrs.

Description: The spatial variability in the mix of species making up Cold-water coral reef communities is not well known. In this study abundances of a selection of megafauna (Lophelia pertusa, Madrepora oculata, Paragorgia arborea, Primnoa resedaeformis, Mycale lingua, Geodia baretti, Acesta excavata and fish) were quantified throughout 9 manned submersible video transects from 3 reef complexes (Røst Reef, Sotbakken Reef and Traena Reef) on the Norwegian margin. Substrate type (coral structure, rubble, exposed hardground or soft sediment) was also recorded. Variations in the densities of these fauna (with respect to both reef complex and substrate type) were investigated, with spatial covariance between species assessed. For the majority of fauna investigated, densities varied by both reef and substrate. Spatial covariance indicated that some species may be utilising similar habitat niches, but that minor environmental differences may favour colonisation by one or other at a particular reef. Fish densities were generally higher in regions with biogenic substrate (coral structure and coral rubble substrates) than in areas of soft or hardground substrate. Further, fish were more abundant at the northerly Sotbakken Reef at time of study than elsewhere. Community structure varied by reef, and therefore management plans aimed at maintaining the biodiversity of reef ecosystems on the Norwegian margin should take this lack of homogeneity into account.

Description: Solid-solution partitioning of Ra determines the dissolved Ra composition of porewater in marine sands. Therefore, sorption controls also influence the endmember concentration of Ra in submarine groundwater discharge (SGD). Ra is widely used as a tracer of SGD, and constraining sorption controls in permeable sands is necessary to evaluate spatial and temporal variation in Ra groundwater activities. This work presents Ra distribution coefficients measured in seawater (salinity 35) for some common solid sorbents as well as different solution compositions relevant to permeable marine sands and the subterranean estuary. There was a strong correlation of Ra distribution coefficient (Kd = solid-phase Ra/solution Ra) with surface area for size-fractionated sediments (log Kd (L/g) = 0.77 [log S.A. (m2/g)] + 0.73; r2 = 0.76). Ra sorption showed no direct relationship with solid-phase Fe or Mn content of the sands, although removal of visible surficial oxide coatings with dilute acid reduced Kd by a factor of 2 to 3. Synthetic Fe-oxides showed nearly two orders of magnitude difference in Ra sorption. Ferrihydrite had the highest Ra sorption coefficient at 1535 ± 410 L kg− 1, followed by lepidocrocite (174 ± 21 L kg− 1), hematite (75 ± 17 L kg− 1), and goethite (20 ± 8 L kg− 1). A marked increase in Ra adsorption was observed with increasing pH, with the sorption edge of natural sands falling within the pH range of 5–8. The extent of Ra sorption at a given pH varied among different substrates. No effect of dissolved Fe was observed on Ra partitioning. A large increase in Ra Kd was evident with increasing Ba concentration when seawater contained sulfate, opposite the effect that would be expected for sorption competition. No effect of Ba concentration was observed when sulfate was excluded from the ASW, indicating that barite precipitation caused the Kd increase. There was no clear effect of temperature on Ra sorption between 2 and 60 °C. Results of this study show that minor solid-phase components increase the Ra sorption capacity of bulk sands and buffer the dissolved Ra concentration (i.e., the SGD endmember). Solution controls on Ra sorption have the potential to greatly alter the Ra composition of discharging groundwater. Given that high-salinity, high-pH conditions probably prevail in porewater below the sediment–water interface, the actual SGD Ra endmember may be less variable than suggested by compilations that include groundwater from deep and fresh groundwater. Highlights ► Variable Ra partitioning to size-fractionated and diverse sediments was primarily controlled by specific surface area. ► Ra displayed pH-dependent sorption to sands, with a sorption edge between pH 5 and 8. ► No effect on Ra partitioning was observed for temperature or competition by dissolved Fe and Ba.

Description: There is mounting evidence that driving on the beach has a significant biophysical impact, and it has been suggested in a number of recent studies that driving on the beachface leads to a net loss of sediment from the beach-dune system. Identifying a conclusive link between beach driving and beach erosion is, however, complicated by the natural variability of the environment in both space and time, and it has proven difficult to distinguish the driving signal from this background noise. In this respect, the impacts of beach driving are not clear, making it difficult to develop appropriate management strategies to reduce the impact in either degree or extent. LiDAR data from both Padre Island National Seashore and Assateague Island National Seashore are used in the present study to determine if the differences in beach and dune morphology between restricted and open access sections of the beach are associated with beach driving. Results from Padre Island National Seashore suggest that beach driving does not affect the height and volume of the foredunes, but is responsible for a statistically significant decrease in the elevation of the dune crest and base compared to the control section of beach. The decrease in elevation is ascribed to the compaction and pulverization of seaweed wrack that accumulates along the Texas coast in the spring and summer months, and is responsible for the anchoring of sediment for the growth of new vegetation seaward of the foredune. At Assateague Island National Seashore, driving on the beach is shown to cause a statistically significant change in the beach-dune morphology, with smaller dunes set further back from the shoreline within the open access sections of the beach. Despite the changes in dune morphology at both sites, there is no statistically significant difference in beach-dune volume on either side of the beach access road, which suggests that driving on the beach does not lead to a net loss of sediment from the beach-dune system. Driving on the beach does, however, make the foredune at both sites susceptible to scarping and overwash during tropical storms and hurricanes.

Description: The volcanic centers of Kos, Yali and Nisyros lie at the eastern edge of the Hellenic Volcanic Arc. Recent swath bathymetric surveys and seismic profiling, conducted by HCMR, led to the discovery of several submarine volcanic centers and massive underwater volcaniclastic deposits. Further research aboard the E/V “Nautilus” was conducted at the area in October 2010. Avyssos crater, located northeast of Strongyli islet, is believed to have been the original location of the massive eruption of Kos ignimbrite 160,000 years ago. Exploration of Avyssos showed that it the seafloor is mostly covered with fine-grained sediment full with traces of bioturbation. Hydrothermal activity was not evident at any point. Yali and Strongyli represent Late Pleistocene to Holocene volcanic islands that have developed between the islands of Kos and Tilos. ROV exploration of the eastern flank of Yali revealed wave-type sediment structures, as well as linear fractures at various depths. Several smaller craters were also discovered on the northwest slopes of Strongyli, aligned with ENE-WSW trending fractures with no signs of hydrothermal activity. Heavy biogenic encrustations cover the volcanic rock outcrops on the flanks of both Yali and Strongyli. Analysis of recovered samples will provide information about their relationship to the geology of the nearby islands.

Description: Digital macro photography and settling tests were carried out to investigate the morphological and settling characteristics of ANAMMOX granules in a high-rate reactor. The ANAMMOX granules could be divided into settling and floating granules. The settling granules with an average diameter of 2.96 ± 0.99 mm were smaller than the floating granules with an average diameter of 4.58 ± 1.22 mm. A settling model was established and validated to correlate the settling velocity with the density (ρG), mass shape factor (ψmass), shape-correction factor (characterized by sphericity (Φ′) or roundness (ξ)) and projected area equivalent sphere diameter (dP) of ANAMMOX granules. The sphericity was more suitable than the roundness for describing the settling behavior. The sensitivity of four parameters was in the order of ρG, ψmass, dP and Φ′. Based on the settling model, ANAMMOX granules with diameter of 1.75–4.00 mm were supposed to be optimal for the ANAMMOX process.

Description: A chemical study of the lichen Ramalina siliquosa complex found in Brittany was conducted. Eight chemotypes were considered and their chemical composition was elucidated for the first time by LC–MS analysis. Ten main compounds were identified: conhypoprotocetraric acid (1), salazinic acid (2), peristictic acid (3), cryptostictic acid (4), protocetraric acid (5), stictic acid (6), norstictic acid (7), hypoprotocetraric acid (8), 4-O-demethylbarbatic acid (9), (+)-usnic acid (10) and 22 minor compounds were reported. The MS/MS fragmentation patterns of each compound of R. siliquosa complex were determined and proposed.

Description: The coral species Paragorgia arborea and Primnoa resedaeformis are abundant and widely distributed gorgonians in North Atlantic waters. Both species add significant habitat complexity to the benthic environment, and support a host of invertebrate species. Mapping their distribution is an essential step in conservation and resource management, but challenging as a result of their remoteness. In this study, three predictive models — Ecological Niche Factor Analysis, Genetic Algorithm for Rule-set Production and Maximum Entropy modeling (MaxEnt) were applied to predict the distribution of species' suitable habitat across a region of Røst Reef (Norwegian margin) based on multiscale terrain variables. All three models were successful in predicting the habitat suitability for both gorgonian species across the study area, and the MaxEnt predictions were shown to outperform other predictions. All three models predicted the most suitable habitats for both species to mainly occur along the ridges and on the upper section of the large slide, suggesting both species preferentially colonize topographic highs. Jackknife tests for MaxEnt predictions highlighted the seabed aspect in relation to P. arborea distribution, and the seabed relative position (curvature) in relation to the distribution of both species. Given the vulnerability of deep-water corals to anthropogenic impacts, further comparative study over a wider study area would be particularly beneficial for the management of the species.

Description: Oil derived from photosynthetic microalgae is a potential major source of renewable energy, but while industrial-scale efforts to grow algal biomass are underway, it remains an expensive process. The cost of biomass production may be offset by using the algae to simultaneously remediate chemical contaminants from wastewater or natural surface waters. This work examines trace metal accumulation and cycling in algae grown for biofuel use, and evaluates the potential of this approach for remediation purposes. In the system studied, a natural, mixed-species algal community was allowed to develop on a shallow floway fed with water from the York River estuary (VA, USA). Accumulation of metals ranged widely in the algal biomass (Fe 〉 Mn 〉 〉Pb 〉 Cu 〉 V 〉 Cd) and represented removal from the dissolved phase of between 1 and 87% (for Cd and Pb, respectively). These metals were selected for analysis because of their differing geochemical behavior, as well as their importance as micronutrients (Fe, Mn, Cu, V) and toxicants (Pb, Cu, Cd). Most of the algal metal inventory was partitioned in the intracellular fraction (∼30% for Mn, 50–90% for other metals; operationally defined using a chemical wash technique), indicating accumulation due to biochemical demand, not adsorption to cell surfaces. Although algal community composition was similar on the upstream and downstream ends of the floway, the metal inventory was two-fold higher on the downstream end. Differences in metal accumulation may have been related to algal physiology or to pronounced cycles of water pH and dissolved oxygen driven by algal photosynthesis and respiration. Differences in metal removal efficiency and biomass inventory indicate that algal floway systems may be manipulated to optimize remediation of metal-contaminated water.

Description: Submarine groundwater discharge (SGD) to the ocean supplies Sr with less radiogenic 87Sr/86Sr than seawater, and thus constitutes an important term in the Sr isotope budget of the modern ocean. However, few data exist for Sr in coastal groundwater or in the geochemically dynamic subterranean estuary (STE). We examined Sr concentrations and isotope ratios from nine globally-distributed coastal sites and characterized the behavior of Sr in the STE. Dissolved Sr generally mixed conservatively in the STE, although large differences were observed in the meteoric groundwater end-member Sr concentrations among sites (0.1–24 μM Sr). Strontium isotope exchange was observed in the STE at five of the sites studied, and invariably favored the meteoric groundwater end-member signature. Most of the observed isotope exchange occurred in the salinity range 5–15, and reached up to 40% exchange at salinity 10. Differences in fresh groundwater Sr concentrations and isotope ratios (87Sr/86Sr = 0.707–0.710) reflected aquifer lithology. The SGD end-member 87Sr/86Sr must be lower than modern seawater (i.e., less than 0.70916) in part because groundwater Sr concentrations are orders of magnitude higher in less-radiogenic carbonate and volcanic island aquifers. A simple lithological model and groundwater Sr data compiled from the literature were used to estimate a global average groundwater end-member of 2.9 μM Sr with 87Sr/86Sr = 0.7089. This represents a meteoric-SGD-driven Sr input to the ocean of 0.7–2.8 × 1010 mol Sr y−1. Meteoric SGD therefore accounts for 2–8% of the oceanic Sr isotope budget, comparable to other known source terms, but is insufficient to balance the remainder of the budget. Using reported estimates for brackish SGD, the estimated volume discharge at salinity 10 (7–11 × 1015 L y−1) was used to evaluate the impact of isotope exchange in the STE on the brackish SGD Sr flux. A moderate estimate of 25% isotope exchange in the STE gives an SGD Sr end-member 87Sr/86Sr of 0.7091. The brackish SGD Sr flux thus accounts for 11–23% of the marine Sr isotope budget, but does not appear sufficient to balance the ∼40% remaining after other known sources are included. Substantial uncertainties remain for estimating the SGD source of Sr to the global ocean, especially in the determination of the volume flux of meteoric SGD, and in the paucity of measurements of groundwater Sr isotope composition in major SGD regions such as Papua New Guinea, the South America west coast, and West Africa. Consequently, our global estimate should be viewed with some caution. Nevertheless, we show that the combined sources of meteoric SGD and brackish SGD coupled with isotope exchange in the STE may constitute a substantial component (∼13–30%) of the modern oceanic 87Sr/86Sr budget, likely exceeding less radiogenic Sr inputs by sedimentary diagenesis and hydrothermal circulation through the mid-ocean ridge system. Temporal variation in SGD Sr fluxes and isotope composition may have contributed to fluctuations in the oceanic 87Sr/86Sr ratio over geologic time.