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Cornelia Saukel Rüdiger Stein Christoph Vogt Vladimir P. Shevchenko 《Geo-Marine Letters》2010,30(6):605-616
In this study, the grain-size and clay-mineral compositions of 73 surface sediment samples collected in a variety of environmental
settings in the White Sea are presented to characterize recent sedimentation processes, reconstruct transport pathways, and
identify potential source areas of the terrigenous components. Areas >100 m deep are invariably characterized by silty clay,
whereas areas <100 m deep exhibit more heterogeneous grain-size compositions plausibly explained by coastal erosion and (re-)distribution
mechanisms, particularly tidal currents. The dominance of sand in the estuarine areas of the Onega and Dvina rivers as well
as toward the Gorlo Strait connecting the White Sea with the Barents Sea is attributed to increased current speeds. Illite
and smectite are the dominant clay minerals in recent sediments of the southwestern and eastern White Sea sectors, respectively.
Their distribution patterns largely depend on the geology of the source areas, and mirror surface circulation patterns, especially
in Dvina Bay. Smectite is a key clay mineral in White Sea surface sediments, as it reveals the dominating influence of the
Northern Dvina’s runoff on sedimentation and water circulation throughout the basin. In comparison to other Eurasian shelf
seas, the White Sea is characterized by a greater diversity of clay-mineral assemblages, which range from illite- to smectite-dominated
sectors containing variable amounts of chlorite and kaolinite. 相似文献
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Xavier Faïn Daniel Obrist Cornelia Barth Douglas P. Boyle 《Geochimica et cosmochimica acta》2011,75(9):2379-2392
Few data are available on mercury (Hg) dynamics at high-elevation mountain sites. In this project, a whole-watershed approach was used to quantify major fluxes and pools of Hg in Sagehen basin, a closed basin in the Sierra Nevada mountains in California. Over a period spanning 9 months (January-September 2009), we estimated wet deposition inputs to the watershed at 3.8 μg m−2. Dry deposition added additional Hg in the range of 0.30-2.45 μg m−2 during this time period, and was the dominant deposition process during summer time. Seasonal snowpack accounted for only half of the Hg deposited by wet deposition. We suggest that photo-induced reduction of Hg(II) in snow and subsequent volatilization was responsible for this loss. Thus, snowpacks in the Sierra Nevada mountains likely reduce the effective atmospheric mercury flux via wet deposition due to significant emission fluxes prior to snowmelt. As such, wet Hg deposition could be of lesser importance as a Hg source in snow-dominated systems. Finally, stream runoff collected at the outlet of the watershed could account for only 4% of total Hg wet deposition suggesting that a large fraction of mercury deposition was sequestered in the ecosystem, specifically in the soils. 相似文献
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Cornelia Kriete 《Geostandards and Geoanalytical Research》2011,35(3):319-340
Round 23 of the GeoPT international proficiency testing scheme included the ferromanganese nodule powder FeMn‐1 which was distributed as an additional sample (23A). The aim of this initiative was to assess overall analytical performance for such a challenging oxide matrix with a view to the possible certification of such a material in accordance with ISO Guide requirements. To investigate inter‐method discrepancies, precision data and the method means for the most frequently used analytical methods (XRF, ICP‐MS and ICP‐AES) and sample preparation techniques were calculated and then compared using statistical tests of equivalence. For most major elements, XRF and ICP‐AES data dominated and these were found to give equivalent results. In contrast, for most trace elements significant discrepancies were detected between data obtained by different analytical methods. Possible causes are discussed with a view to attributing their origin to calibration strategy, sensitivity or interferences. It is assumed that the unusual oxide matrix generated unexpected interferences and thus method bias. Discrepancies observed between data from different analytical methods provide valuable information for the participating analysts, helping them to avoid systematic errors and thus minimising bias. They also suggest actions necessary to improve results for any future certification of such a material. 相似文献
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Anton?le?RoexEmail author Cornelia?Class 《Contributions to Mineralogy and Petrology》2014,168(2):1046
In situ trace element analyses of constituent minerals in mantle xenoliths occurring in an alnöite diatreme and in nephelinite plugs emplaced within the central zone of the Damara Belt have been determined by laser ablation ICP-MS. Primitive mantle-normalized trace element patterns of clinopyroxene and amphibole indicate the presence of both depleted MORB-like mantle and variably enriched mantle beneath this region. Clinopyroxenes showing geochemical depletion have low La/Smn ratios (0.02–0.2), whereas those showing variable enrichment have La/Smn ranging up to 3.8 and La/Ybn to 9.1. The most enriched clinopyroxenes coexist with amphibole showing similar REE patterns (La/Smn = 1.3–4.1; La/Ybn = 4.5–9). Primitive mantle-normalized trace element patterns allow further groups to be distinguished amongst the variably enriched clinopyroxenes: one having strong relative depletion in Rb–Ba, Ta–Nb and relative enrichment in Th–U; another with similar characteristics but with additional strong relative depletion in Zr–Hf; and one showing no significant anomalies. Amphiboles show similar normalized trace element patterns to co-existing clinopyroxene. Clinopyroxene and amphiboles showing LREEN enrichment have high Sr and low Nd isotope ratios compared to clinopyroxene with LREE-depleted patterns. Numerical simulation of melt percolation through the mantle via reactive porous flow is used to show that the chromatographic affect associated with such a melt migration process is able to account for the fractionation seen in La–Ce–Nd in cryptically metasomatized clinopyroxenes in Type 1 xenoliths, where melt–matrix interactions occur near the percolation front, whereas REE patterns in clinopyroxenes proximal to the source of metasomatic melt/fluid match those found in modally metasomatized Type 2 xenoliths. The strong fractionation between Rb–Ba, Th–U and Ta–Nb shown by some cryptically metasomatized xenoliths can be also accounted for by reactive porous flow, provided amphibole crystallizes from the percolating melt/fluid close to its source. The presence of amphibole in vein-like structures in some xenoliths is consistent with this interpretation. The strong depletion in Zr–Hf in clinopyroxene and amphibole in some xenoliths cannot be accounted for by melt migration processes and requires metasomatism by a separate carbonate-rich melt/fluid. When taken together with published isotope data on these same xenoliths, the source of metasomatic enrichment of the previously depleted (MORB-like) sub-Damaran lithospheric mantle is attributed to the upwelling Tristan plume head at the time of continental breakup. 相似文献
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Wolfgang Reiter Simon Elfert Christoph Glotzbach Matthias Bernet Cornelia Spiegel 《Basin Research》2013,25(6):659-674
Despite abundant data on the early evolution of the Central Alps, the latest stage exhumation history, potentially related to relief formation, is still poorly constrained. We aim for a better understanding of the relation between glaciation, erosion and sediment deposition. Addressing both topics, we analysed late Pliocene to recent deposits from the Upper Rhine Graben and two modern river sands by apatite fission‐track and (U‐Th‐Sm)/He thermochronology. From the observed age patterns we extracted the sediment provenance and paleo‐erosion history of the Alpine‐derived detritus. Due to their pollen and fossil record, the Rhine Graben deposits also provide information on climatic evolution, so that the erosion history can be related to glacial evolution during the Plio‐Pleistocene. Our data show that Rhine Graben deposits were derived from Variscan basement, Hegau volcanics, Swiss Molasse Basin, and the Central Alps. The relations between glaciation, Alpine erosion, and thermochronological age signals in sedimentary rocks are more complex than assumed. The first Alpine glaciation during the early Pleistocene did not disturb the long‐term exhumational equilibrium of the Alps. Recent findings indicate that main Alpine glaciation occurred at ca. 1 Ma. If true, then main Alpine glaciation was coeval with an apparent decrease of hinterland erosion rates, contrary to the expected trend. We suggest that glaciers effectively sealed the landscape, thus reducing the surface exposed to erosion and shifting the area of main erosion north toward the Molasse basin, causing sediment recycling. At around 0.4 Ma, erosion rates increased again, which seems to be a delayed response to main glaciation. The present‐day erosion regime seems to be dominated by mass‐wasting processes. Generally, glacial erosion rates did not exceed the pre‐glacial long‐term erosion rates of the Central Alps. 相似文献
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Jochen Schanze Johanna Trümper Cornelia Burmeister Dirk Pavlik Ivan Kruhlov 《Environmental Earth Sciences》2012,65(5):1405-1414
The paper presents a methodology on how to consistently deal with the future change and management options in integrated water
resources management (IWRM). It is based on a conceptual framework with a five step procedure for the formulation and analysis
of a so-called ‘parameterised regional futures’. Developing and testing the approach for IWRM is realised for the upper part
of the Western Bug River catchment (Ukraine). Special attention is paid to scenarios of change covering climate and land use.
The future regional climate is downscaled with the model CCLM. Land cover is projected after retrospective change detection
and the derivation of prospective algorithms. Parameters of the interrelations between land use and the water cycle are tackled
through using the concept of the model PWF-LU. The methodology is currently being tested to analyse the impacts of mid-term
regional change and management options on the water cycle of the catchment. 相似文献
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Very little is known about the macromolecular properties of biomass combustion residues referred to as black carbon (BC). Pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS) was performed on: (i) peat from Spain at 400–1200 °C to investigate the effect of charring on pyrolysis fingerprint and (ii) natural charcoal from Laos in order to link molecular information to published chemical and reactivity parameters. Confirming earlier Py-GC/MS studies, the BC in the artificially charred peat and the natural charcoal produced predominantly benzene, toluene, C2-benzenes, PAHs and benzonitriles. Furthermore, some charcoal samples produced significant amounts of phenols, methoxyphenols, carbohydrate markers, n-alkanes and n-alkenes upon pyrolysis, reflecting non-charred and weakly charred biomass. A series of pyrolysis product ratios related to the degree of dealkylation of the pyrolysis products (benzene/toluene, naphthalene/C1-naphthalenes, C1-naphthalenes/C2-naphthalenes, benzofuran/C1-benzofurans and benzonitrile/C1-benzonitrile) increased with increasing artificial charring (peat) and, for the natural charcoal, these ratios were in accordance with established chemical and reactivity parameters related to charring intensity from other methods: proportion of aromatic C obtained from solid state 13C nuclear magnetic resonance spectroscopy (NMR), the proportion of charred material as estimated from NMR in conjunction with a molecular mixing model (NMR–MMM) and the resistance to acid dichromate oxidation. The alkyl side chains of aromatic pyrolysis products are probably inherited from short chain aliphatic C chains that cross link the predominantly aromatic building blocks of BC, and these linkages seem to disappear with increasing charring intensity. Thus, the degree of thermal alteration of BC can be discerned from the pyrolysis fragmentation pattern. 相似文献