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Shumilovskikh L.S.,University of Gottingen | Marret F.,University of Liverpool | Fleitmann D.,Institute of Geological science | Fleitmann D.,University of Bern | And 3 more authors.
Marine Micropaleontology | Year: 2013

In order to compare the sea-surface conditions in the Black Sea during the Holocene and Eemian, sapropelic parts of marine core 22-GC3 (42°13.53'N/36°29.55'E, 838. m water depth) were studied for organic-walled dinoflagellate cyst content. The record shows a change from freshwater/brackish assemblages (Pyxidinopsis psilata, Spiniferites cruciformis, and Caspidinium rugosum) to more marine assemblages (Lingulodinium machaerophorum and Spiniferites ramosus complex) during each interglacial, due to the inflow of saline Mediterranean water. The lacustrine-marine transitions in 22-GC3 occurred at ~. 8.3. cal. kyr BP during the early Holocene and ~. 128. kyr BP during the early Eemian, slightly later compared to the onset of interglacial conditions on the adjacent land. Dinoflagellate cyst assemblages reveal higher sea-surface salinity (~. 28-30) (e.g. Spiniferites pachydermus, Bitectatodinium tepikiense, and Spiniferites mirabilis) around ~. 126.5-121. kyr BP in comparison to the Holocene (~. 15-20) as well as relatively high sea-surface temperature (e.g. Tuberculodinium vancampoae, S. pachydermus, and S. mirabilis) especially at ~. 127.6-125.3. kyr BP. Establishment of high sea-surface salinity during the Eemian correlates very well with reconstructed relatively high global sea-level and is explained as a combined effect of increased Mediterranean supply and high temperatures at the beginning of the last interglacial. The observed changes in the dinocyst record highlight the importance of nutrients for the composition of the Eemian and Holocene dinocyst assemblages. © 2013 Elsevier B.V.

Shumilovskikh L.S.,University of Gottingen | Fleitmann D.,University of Reading | Fleitmann D.,Institute of Geological science | Fleitmann D.,University of Bern | And 5 more authors.
Climate of the Past | Year: 2014

High-resolution pollen and dinoflagellate cyst records from sediment core M72/5-25-GC1 were used to reconstruct vegetation dynamics in northern Anatolia and surface conditions of the Black Sea between 64 and 20 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the concomitant presence of temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia. Long-term glacial vegetation dynamics reveal two major arid phases ∼64-55 and 40-32 ka BP, and two major humid phases ∼54-45 and 28-20 ka BP, correlating with higher and lower summer insolation, respectively. Dansgaard-Oeschger (D-O) cycles are clearly indicated by the 25-GC1 pollen record. Greenland interstadials are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm/wet conditions in northern Anatolia, whereas Greenland stadials reveal cold and arid conditions as indicated by spread of xerophytic biomes. There is evidence for a phase lag of ∼500 to 1500 yr between initial warming and forest expansion, possibly due to successive changes in atmospheric circulation in the North Atlantic sector. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates brackish Black Sea conditions during the entire glacial period. The decrease of marine indicators (marine dinocysts, acritarchs) at ∼54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water. This freshening is possibly related to humid phases in the region, to connection between Caspian Sea and Black Sea, to seasonal freshening by floating ice, and/or to closer position of river mouths due to low sea level. In the southern Black Sea, Greenland interstadials are clearly indicated by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity. Heinrich events show a similar impact on the environment in the northern Anatolia/Black Sea region as Greenland stadials. © Author(s) 2014.

Angiboust S.,Helmholtz Center Potsdam | Pettke T.,Institute of Geological science | De Hoog J.C.M.,University of Edinburgh | Caron B.,CNRS Institute of Earth Sciences | Oncken O.,Helmholtz Center Potsdam
Journal of Petrology | Year: 2014

The Monviso ophiolite Lago Superiore Unit (LSU;Western Alps) constitutes a well-preserved, largely coherent fragment of eclogitic upper oceanic lithosphere subducted to c. 80 km depth (between 50 and 40Ma) and exhumed along the subduction interface.Withinslab, 10-100 m thick, eclogite-facies shear zones cut this section; the Intermediate Shear Zone (ISZ) follows the boundary between gabbroic and basaltic eclogites (associated with minor calcschist lenses), and the Lower Shear Zone (LSZ) marks the contact between gabbroic eclogites and the antigorite serpentinite sole. Up to 10 m fragments of mylonitic gabbroic eclogites were transported within serpentinite schists from the LSZ during eclogite-facies deformation. Metasomatic rinds, formed on these fragments during peak to early retrograde lawsonite-eclogite-facies metamorphism (c. 550°C and 2·6 GPa), document episodic, prominent rock-fluid interaction along intra-slab, channelized fluid migration pathways associated with deformation. We present new petrological and geochemical data on hydrous eclogites (talc-, chlorite-, lawsoniteand phengite-bearing eclogites) and serpentinite-derived ultrabasic schists from block rinds. Bulk-rock compositions, laser ablation inductively coupled plasma mass spectrometry mineral analyses and X-ray Cr and Mg maps of garnet and clinopyroxene demonstrate that these samples underwent significant enrichments in Mg, Cr, Ni,large ion lithophile elements and prominent depletions in Fe and V during eclogite-facies metasomatism. Boron isotope data for phengite (δ11B=0 to+7‰; 80

Schlich K.,Fraunhofer Institute for Molecular Biology and Applied Ecology | Klawonn T.,Fraunhofer Institute for Molecular Biology and Applied Ecology | Terytze K.,Institute of Geological science | Hund-Rinke K.,Fraunhofer Institute for Molecular Biology and Applied Ecology
Environmental Sciences Europe | Year: 2013

Background: Silver nanoparticles (AgNPs) are widely used in many fields of application and consumer products due to their antibacterial properties. The aim of this study was to prepare a hazard assessment for one specific AgNP in soil, incorporated via sewage sludge (the sewage sludge pathway). The effects of pristine AgNPs on microorganisms, plants and earthworms were first determined in screening tests. Long-term tests over 140 days were then conducted with AgNPs added to soil via sewage sludge. AgNPs were incorporated into the sludge through a simulated sewage treatment plant (STP) over 10 days to allow transformation to occur and also by manual spiking over 2 h. The results of the most sensitive organism from the long-term tests, the soil microorganisms, are presented. Results: The STP simulations confirmed that at environmentally relevant concentrations >90% of AgNPs remain bound to sewage sludge. Effects of AgNPs bound to sewage sludge and added to soil were similar to that of pristine NM-300K after degradation of the sludge. The predicted no-effect concentration for NM-300K in soil of 0.05 mg/kg dry soil determined a maximum threshold of 30 mg/kg dry sludge per application, considering the maximum addition of sewage sludge in Germany (5 tons per hectare every 3 years). Conclusion: At environmentally relevant concentrations, AgNP absorption to sludge and aging in soil (even after transformation) cause toxic effects on soil microorganisms of the terrestrial ecosystem. © 2013 Schlich et al.; licensee Springer.

Arndt J.E.,Alfred Wegener Institute for Polar and Marine Research | Schenke H.W.,Alfred Wegener Institute for Polar and Marine Research | Jakobsson M.,University of Stockholm | Nitsche F.O.,Lamont Doherty Earth Observatory | And 12 more authors.
Geophysical Research Letters | Year: 2013

The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-Antarctic waters south of 60°S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Oceans (GEBCO). The IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single-beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 × 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at http://dx.doi.org/10.1594/PANGAEA.805736. Key Points The first regional bathymetric compilation covering the entire Southern Ocean A new keystone dataset for Antarctic research The southern equivalent to IBCAO is now released ©2013. American Geophysical Union. All Rights Reserved.

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