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Braunschweig, Germany

Rogasik H.,Leibniz Center for Agricultural Landscape Research | Schrader S.,Thunen Institute TI | Onasch I.,Leibniz Center for Agricultural Landscape Research | Kiesel J.,Leibniz Center for Agricultural Landscape Research | Gerke H.H.,Leibniz Center for Agricultural Landscape Research

The burrowing activity of earthworms leads to soil structural changes by compaction of surrounded soil matrix, which represents the so-called drilosphere. This is a distinct volume around the resulting macropore, which controls various soil processes. In the aim to detect the bulk density variation around earthworm burrows, two repacked soil columns from a silt loam with defined water content and bulk density were created, separately inoculated with the anecic earthworm species Lumbricus terrestris, stored under constant conditions for 7weeks and finally analyzed by means of X-ray computed tomography. A basic voxel approach was developed to conduct a gapless analysis of the drilosphere and surrounding soil matrix. The measured Hounsfield Units of basic voxels (pixel size of 0.25mm and slice thickness of 0.625mm) were converted into the corresponding dry bulk density (BD). The initial mean BD of an entire horizontal soil slice was 1.34Mgm-3 (core 1) and 1.38Mgm-3 (core 2). Due to burrowing L. terrestris compacted the inner boundary of the drilosphere (burrow wall) up to a BD of at least 1.75Mgm-3 which equates to more than 30% compared to the soil matrix. The BD decreased from the inner boundary of the drilosphere to its outer boundary, which is a transition zone to the surrounding soil matrix. However, the BD decrease was not concentrically uniform but revealed heterogeneous patterns of zones with different BD-classes. This locally heterogeneous BD distribution is an evidence of radial earthworm forces acting anisotropically. We conclude that BD heterogeneity in the drilosphere of L. terrestris might have notable implications for the understanding of lateral transfer of water and solutes in the soil profile.© 2013 Elsevier B.V. Source

Placencia Pena M.I.,Bern University of Applied Sciences | Placencia Pena M.I.,University of Lorraine | Deutschle A.L.,Sudan University of Science and Technology | Deutschle A.L.,Thunen Institute TI | And 3 more authors.
European Journal of Wood and Wood Products

The solubility in water and carbohydrates/lignin composition after hydrolysis of wood welded by linear friction welding was studied. Welded beech (WB) and welded spruce (WS) were analyzed at welding times (Wt) of 1, 1.5, 2, 2.5, 3 s, and 2, 4, 6, 8, 10, 12 s, respectively. Scratched welded material was first extracted in water, dried, cryo-milled, and then hydrolyzed with sulfuric acid. Maximal percentages of solids dissolved in water were 17.7 and 10 for WB and WS and 2.2 and 1.4 for un-welded beech and spruce, respectively. Among water extracts, lignin, mono-oligosaccharides, acetic acid, vanillin, furfural, 5 hydroxymethylfurfural (5HMF), and syringaldehyde were quantified. Maximal percentages of water soluble lignin in WB and WS were 5 and 3.6, respectively; molecular weight and polydispersity were also determined. Regarding carbohydrates in the water extracts, a maximum of 1.4 % oligosaccharides in WB and 1 % monosaccharides in WS were detected. After hydrolysis, an increase in the amount of Klason lignin and a progressive diminution of some sugars take place at consecutive Wt of WB and WS. This study allows explaining to a good extent the behavior of welded joints face to liquid water. Moreover, the degradation of certain wood components is clearly presented. © 2015, Springer-Verlag Berlin Heidelberg. Source

Gimpel A.,Thunen Institute TI | Stelzenmuller V.,Thunen Institute TI | Grote B.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Alfred Wegener Institute for Polar and Marine Research | And 4 more authors.
Marine Policy

The concept of co-location of marine areas receives an increased significance in the light of sustainable development in the already heavily used offshore marine realm. Within this study, different spatial co-location scenarios for the coupling of offshore aquacultures and wind farms are evaluated in order to support efficient and sustainable marine spatial management strategies. A Geographic Information System (GIS) and multi-criteria evaluation (MCE) techniques were combined to index suitable co-sites in the German exclusive economic zone of the North Sea. The MCE was based on criteria such as temperature, salinity or oxygen. In total, 13 possible aquaculture candidates (seaweed, bivalves, fish and crustaceans) were selected for the scenario configuration. The GIS modelling framework proved to be powerful in defining potential co-location sites. The aquaculture candidate oarweed (Laminaria digitata) revealed the highest suitability scores at 10-20. m depth from April to June, followed by haddock (Melanogrammus aeglefinus) at 20-30. m depth and dulse (Palmaria palmata) and Sea belt (Saccharina latissima) at 0-10. m depth between April and June. In summary, results showed several wind farms were de facto suitable sites for aquaculture since they exhibited high suitability scores for Integrated Multi-Trophic Aquaculture (IMTA) systems combining fish species, bivalves and seaweeds. The present results illustrate how synergies may be realised between competing needs of both offshore wind energy and offshore IMTA in the German EEZ of the North Sea. This might offer guidance to stakeholders and assist decision-makers in determining the most suitable sites for pilot projects using IMTA techniques. © 2015 Elsevier Ltd. Source

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