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Hannover, Germany

Houben G.J.,Federal Institute for Geosciences and Natural Resources | Hauschild S.,State Authority for Mining
Ground Water | Year: 2011

Numerical flow models can be a useful tool for dimensioning water wells and to investigate the hydraulics in their near-field. Fully laminar flow can be assumed for all models calculated up to the screen. Therefore models can be used to predict-at least qualitatively, neglecting turbulent losses inside the well-the spatial distribution of inflow into the well and the overall hydraulic performance of different combinations of aquifer parameters and technical installations. Models for both horizontal (plan view) and vertical flow (cross section) to wells were calculated for a variety of setups. For the latter, this included variations of hydraulic conductivity of the screen, pump position, and aquifer heterogeneity. Models of suction flow control devices showed that they indeed can homogenize inflow, albeit at the cost of elevated entrance losses. © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

Acksel A.,University of Rostock | Amelung W.,University of Bonn | Kuhn P.,University of Tubingen | Gehrt E.,State Authority for Mining | And 2 more authors.
Geoderma Regional | Year: 2016

The genesis of Chernozems in the Baltic Sea region is still insufficiently understood and the composition of its organic matter may be a key for a better pedogenetic interpretation of the mollic, biogenically mixed (Axh) horizons. Therefore, we investigated the composition of soil organic matter in the Ap/Ah- and Axh-horizons from seven soil profiles at the islands of Poel, Fehmarn (Germany), and Sjalland (Denmark). In a multi-methods approach we carried out synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy at the carbon (C) and nitrogen (N) K-edges, pyrolysis-field ionisation-mass spectrometry (Py-FIMS) and soil color measurements as non-specific, bulk SOM characterization methods, and quantified the benzene polycarboxylic acids (BPCAs) as specific markers for black carbon (BC). The XANES- and Py-FIMS-spectra in good agreement revealed relative enrichments of aromatic C and heterocyclic N compounds in the lower Axh- in comparison to the corresponding upper Ap/Ah-horizons. In almost all horizon pairs, the BC portions in the Axh- (7.6 to 18% of Corg) exceeded those in the Ap/Ah-horizons (6.7 to 12% of Corg) and were similar to the BC portions in typical Phaeozems and Chernozems from European loess areas. The ratios of penta- to hexacarboxylic benzoic acids (B5CA/B6CA) of 0.9 to 2.2, mean 1.2, indicated contributions of combustion residues from domestic and grassland fires. This pyrogenic organic matter and its transformation products governed the soil color, which was closely correlated to the BC portions (L∗-value = - 0.880 x + 52.13; r2 = 0.539∗∗). In summary, the enrichments of stabilized aromatic and heterocyclic compounds in the Axh-horizons derived from C- and N-XANES, Py-FIMS and the BC-determination are interpreted by an input of pyrogenic matter into the Baltic Chernozems, indicating an anthropo-pedogenesis in the period between Bronze age and the Early Middle Ages. © 2016 Elsevier B.V. All rights reserved.

Pusch M.,Federal Institute for Geosciences and Natural Resources | Hammer J.,Federal Institute for Geosciences and Natural Resources | Kus J.,Federal Institute for Geosciences and Natural Resources | Klosa D.,State Authority for Mining | And 2 more authors.
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften | Year: 2014

In context of further exploration of the Gorleben salt dome (March 2011 to November 2012) mineralogical and geochemical investigations have been conducted on hydrocarbon-bearing samples of the "Knäuelsalz" (z2HS1), particularly the oldest part of the "Hauptsalz" (Staßfurt Series z2). Investigations focus on genesis, composition and macro-/microstructural distribution of hydrocarbons. These exploration works continue investigations of Gerling & Faber (2001) and Gerling et al. (2002). For this purpose 45 entire cored sampling boreholes supplemented with 20 packer boreholes in Crosscuts 1 West (Q1W) and 1 East (Q1E) have been drilled between March 2011 and March 2012 at the 840 m level of the Gorleben exploration mine in order to get new faultless and unaltered samples beyond the excavation damaged zone. Drill cores of hydrocarbon sampling and packer boreholes have been investigated under ultraviolet light (λ = 254 nm) for indications of the existence of fluorescent (aromatic) hydrocarbons. The results were documented and visualised in the geological 3D model of the Gorleben salt dome. Microscopical studies of thin and thick sections show that hydrocarbons were located at the grain boundaries of halite and/or anhydrite crystals, in newly formed microcracks due to drilling respectively preparational works, in microcapillary tubes of anhydrite crystals and rarely in micro-porous parts of the Hauptsalz.

Richoz S.,Goethe University Frankfurt | Richoz S.,Austrian Academy of Sciences | Van De Schootbrugge B.,Goethe University Frankfurt | Pross J.,Goethe University Frankfurt | And 10 more authors.
Nature Geoscience | Year: 2012

The evolution of complex life over the past 600 million years was disrupted by at least five mass extinctions, one of which occurred at the close of the Triassic period. The end-Triassic extinction corresponds to a period of high atmospheric-CO 2 concentrations caused by massive volcanism and biomass burning; most extinction scenarios invoke the resulting environmental perturbations in accounting for the loss of marine and terrestrial biodiversity. Here we reconstruct changes in Tethyan shallow marine ecosystems and ocean redox chemistry from earliest Jurassic (Hettangian)-aged black shales from Germany and Luxemburg. The shales contain increased concentrations of the biomarker isorenieratane, a fossilized pigment from green sulphur bacteria. The abundance of green sulphur bacteria suggests that the photic zone underwent prolonged periods of high concentrations of hydrogen sulphide. This interval is also marked by the proliferation of green algae, an indicator of anoxia. We conclude that the redox changes in the entire water column reflect sluggish circulation in marginal regions of the Tethys Ocean. We suggest that the resultant repeated poisoning of shallow epicontinental seasg-hotspots of Mesozoic biodiversityg-with hydrogen sulphide may have slowed the recovery of marine ecosystems during the Early Jurassic. © 2012 Macmillan Publishers Limited. All rights reserved.

Klimke J.,Leibniz University of Hanover | Klimke J.,Federal Institute for Geosciences and Natural Resources | Wiederhold H.,Leibniz Institute for Applied Geophysics | Winsemann J.,Leibniz University of Hanover | And 2 more authors.
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften | Year: 2013

The increasing demand on using the subsurface raises the call for a better understanding of the depositional architecture. In this study, we demonstrate how 3D subsurface models can be improved by airborne electromagnetic data. The study area is located in the Pleistocene Quakenbrück Basin in Northern Germany. This overdeepened basin is fronted by a push moraine ridge and fi lled with Middle Pleistocene (Saalian) to Holocene sediments known from a limited amount of borehole data. In 2009, this area was target of an aeroelectromagnetic survey with the SkyTEM system. For the interpretation of SkyTEM resistivity data, a relation between grain size and resistivity was derived using resistivity borehole logs from the larger study area. The analysis of the data showed a positive correlation as resistivity increases with increasing grain size and permeability. Each stratigraphic layer was then modelled with the commercial software GOCAD® based on the geological and geophysical information as each sediment layer is characterised by a specifi c resistivity in the SkyTEM data. Our results demonstrate that by integrating airborne electromagnetic data into geological 3D models, the distribution of stratigraphic units can be modelled with higher lateral resolution due to higher data density. The resistivity-grain size relation can be applied to other study areas with comparable geological conditions. Saline groundwater can clearly be identifi ed and distinguished from non-saline regions in the Quakenbrück Basin by low resistivities. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

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