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Berlin Brandenburg

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  • 1
    In: Der Donauraum, 01/1/2012, Vol.52(2)
    ISSN: 0012-5415
    E-ISSN: 2307-289X
    Source: CrossRef
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  • 2
    In: Physical Chemistry Chemical Physics, 2012, Vol.14(12), pp.4162-4170
    Description: The thermodynamic stability of the acetic acid dimer conformers in microhydrated environments and in aqueous solution was studied by means of molecular dynamics simulations using the density functional based tight binding (DFTB) method. To confirm the reliability of this method for the system studied, density functional theory (DFT) and second order MllerPlesset perturbation theory (MP2) calculations were performed for comparison. Classical optimized potentials for liquid simulations (OPLS) force field dynamics was used as well. One focus of this work was laid on the study of the capabilities of water molecules to break the hydrogen bonds of the acetic acid dimer. The barrier for insertion of one water molecule into the most stable cyclic dimer is found to lie between 3.25 and 4.8 kcal mol 1 for the quantum mechanical methods, but only at 1.2 kcal mol 1 for OPLS. Starting from different acetic acid dimer structures optimized in gas phase, DFTB dynamics simulations give a different picture of the stability in the microhydrated environment (4 to 12 water molecules) as compared to aqueous solution. In the former case all conformers are converted to the hydrated cyclic dimer, which remains stable over the entire simulation time of 1 ns. These results demonstrate that the considered microhydrated environment is not sufficient to dissociate the acetic acid dimer. In aqueous solution, however, the DFTB dynamics shows dissociation of all dimer structures (or processes leading thereto) starting after about 50 ps, demonstrating the capability of the water environment to break up the relatively strong hydrogen bridges. The OPLS dynamics in the aqueous environment showsin contrast to the DFTB resultsimmediate dissociation, but a similar long-term behavior.
    Keywords: Acetic Acid ; Aqueous Solutions ; Breaking ; Density ; Dimers ; Dynamics ; Simulation ; Stability ; Miscellaneous Sciences (So);
    ISSN: 1463-9076
    E-ISSN: 1463-9084
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  • 3
    Language: English
    In: Soil Biology and Biochemistry, 2010, Vol.42(2), pp.155-161
    Description: In alpine environments, climate change may alter vegetation composition as well as the quantity and quality of plant litter, which in turn may affect microbial community composition and functioning. In this study, we analyzed soil microbial community composition and its activity along a vegetation gradient (900–1900 m above sea level (a.s.l.)) in the Austrian Limestone Alps. Soil pH and C:N ratios were significantly different under different plant communities and ranged from 3.9 to 6.1 and from 29 to 17, respectively. The highest amounts of microbial biomass, estimated by the sum of microbial phospholipid fatty acids (total PLFAs), were found at sites with high pH and low C:N ratio, i.e. in alpine grassland and beech forest sites (3.9 ± 0.05 and 3.4 ± 0.7 μmol per g organic carbon (OC), respectively), and the lowest amounts were found at sites with low pH and high C:N ratio, i.e. sites with high percentage of conifers and acidophilic vegetation (around 2 μmol (g OC) ). Total and bacterial PLFAs as well as microbial activity (dimethyl sulphoxide reduction) did not show consistent altitudinal trends. The fungal PLFA 18:2ω6,9 was significantly higher in the forest sites (between 9.2 and 6.7 mol%) compared to the shrubland and grassland sites (between 4.5 and 2.3 mol%). A similar trend was found for ergosterol contents. As a consequence, the bacterial to fungal biomass ratio increased significantly from forest sites to shrubland and grassland sites. Expected future upward migration of the tree line in alpine environments in response to climate warming will therefore increase the abundance of fungi in these ecosystems.
    Keywords: Leptic Histosols ; Climosequence ; Dmso ; Ergosterol ; Litter Layer ; Phospholipid Fatty Acids ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 4
    In: Die Bodenkultur: Journal of Land Management, Food and Environment, 08/24/2018, Vol.69(1), p.1
    Keywords: Agriculture;
    ISSN: Die Bodenkultur: Journal of Land Management, Food and Environment
    E-ISSN: 0006-5471
    Source: CrossRef
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  • 5
    In: Die Bodenkultur: Journal of Land Management, Food and Environment, 2018, Vol.68(4), pp.271-271
    Keywords: Agriculture;
    E-ISSN: 0006-5471
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  • 6
    Language: English
    In: Soil biology & biochemistry, 2010, Vol.42, pp.155-161
    Description: In alpine environments, climate change may alter vegetation composition as well as the quantity and quality of plant litter, which in turn may affect microbial community composition and functioning. In this study, we analyzed soil microbial community composition and its activity along a vegetation gradient (900–1900 m above sea level (a.s.l.)) in the Austrian Limestone Alps. Soil pH and C:N ratios were significantly different under different plant communities and ranged from 3.9 to 6.1 and from 29 to 17, respectively. The highest amounts of microbial biomass, estimated by the sum of microbial phospholipid fatty acids (total PLFAs), were found at sites with high pH and low C:N ratio, i.e. in alpine grassland and beech forest sites (3.9 ± 0.05 and 3.4 ± 0.7 μmol per g organic carbon (OC), respectively), and the lowest amounts were found at sites with low pH and high C:N ratio, i.e. sites with high percentage of conifers and acidophilic vegetation (around 2 μmol (g OC)−1). Total and bacterial PLFAs as well as microbial activity (dimethyl sulphoxide reduction) did not show consistent altitudinal trends. The fungal PLFA 18:2ω6,9 was significantly higher in the forest sites (between 9.2 and 6.7 mol%) compared to the shrubland and grassland sites (between 4.5 and 2.3 mol%). A similar trend was found for ergosterol contents. As a consequence, the bacterial to fungal biomass ratio increased significantly from forest sites to shrubland and grassland sites. Expected future upward migration of the tree line in alpine environments in response to climate warming will therefore increase the abundance of fungi in these ecosystems. ; Includes references ; p. 155-161.
    Keywords: Soil Bacteria ; Soil Ph ; Alpine Plants ; Altitude ; Vegetation ; Soil Ecology ; Climate Change ; Plant Litter ; Shrublands ; Spatial Variation ; Mountains ; Soil Microorganisms ; Soil Fungi ; Montane Forests ; Plant Communities ; Grasslands ; Carbon Nitrogen Ratio ; Microbial Activity ; Ecological Function ; Microbial Ecology
    ISSN: 0038-0717
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 7
    In: Global Change Biology, July 2014, Vol.20(7), pp.2272-2285
    Description: Lignin is an aromatic plant compound that decomposes more slowly than other organic matter compounds; however, it was recently shown that lignin could decompose as fast as litter bulk carbon in minerals soils. In alpine istosols, where organic matter dynamics is largely unaffected by mineral constituents, lignin may be an important part of soil organic matter (). These soils are expected to experience alterations in temperature and/or physicochemical parameters as a result of global climate change. The effect of these changes on lignin dynamics remains to be examined and the importance of lignin as SOM compound in these soils evaluated. Here, we investigated the decomposition of individual lignin phenols of maize litter incubated for 2 years in Histosols on an Alpine elevation gradient (900, 1300, and 1900 m above sea level); to this end, we used the cupric oxide oxidation method and determined the phenols’ C signature. Maize lignin decomposed faster than bulk maize carbon in the first year (86 vs. 78% decomposed); however, after the second year, lignin and bulk C decomposition did not differ significantly. Lignin mass loss did not correlate with soil temperature after the first year, and even correlated negatively at the end of the second year. Lignin mass loss also correlated negatively with the remaining maize N at the end of the second year, and we interpreted this result as a possible negative influence of nitrogen on lignin degradation, although other factors (notably the depletion of easily degradable carbon sources) may also have played a role at this stage of decomposition. Microbial community composition did not correlate with lignin mass loss, but it did so with the lignin degradation indicators (Ac/Al)s and S/V after 2 years of decomposition. Progressing substrate decomposition toward the final stages thus appears to be linked with microbial community differentiation.
    Keywords: C ; Compound‐Specific Isotope Analysis ; Cupric Oxide ; Histosols ; Lignin ; Plfa ; Soil Microbial Communities ; Soil Organic Matter
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 8
    Language: English
    In: Journal of Environmental Management, 15 January 2017, Vol.186, pp.167-174
    Description: Extensive contamination of grassland with cadmium (Cd), lead (Pb) and zinc (Zn) is a typical problem close to Pb/Zn smelter sites. The entry of Cd or Pb into the food chain is very likely, as are toxicity effects of Zn in plants. Previous promising results from pot and field experiments showed the high potential of using amendments for immobilisation to reduce metal input into the food chain via crops grown on smelter-contaminated soils at Arnoldstein (Austria) (Friesl et al., 2006). The aim of this study was to find a practical solution for large-scale contaminations in hilly regions that avoids erosion. Field application of amendments without destroying the vegetation cover (grassland) involved two approaches: (a) slurrying (Slu) the amendments into cut gaps in the vegetation cover and (b) injecting (Inj) the amendments through the vegetation cover. Here, we investigate the immobilising and long-term efficiency of treatments [gravel sludge (2.5%) + red mud (0.5%) (GS + RM)]. Risk assessment was based on soil, plant and water samples taken over a period of 10 years. Ammonium-nitrate-extractable Cd was reduced up to 50%, Pb up to 90%, and Zn over 90%. Plant uptake into the grass mixture and narrow leaf plantain was significantly reduced for Cd, Pb, and Zn. Harvesting early in vegetation period can further reduce uptake and meet the threshold for fodder crops. The reduction of these elements in the seepage water in 24 samplings within these 10 years reached 40%, 45% and 50%, respectively. Immobilisation increased microbial biomass and decreased human bioaccessibility for Pb. Our investigation of the long-term efficiency of GS + RM in all treatments shows that the Slu and Inj amendment application techniques have promising potential as a realistic and practical method for extensively contaminated hilly land. Slurrying performed best. We conclude that grassland remediation methods involving tillage are counterproductive from the viewpoint of bioaccessibility and soil protection and therefore should be avoided.
    Keywords: Field Experiment ; Immobilisation ; Large-Scale Contamination ; Gentle Remediation Options ; Microbial Biomass ; Grassland ; Environmental Sciences ; Economics
    ISSN: 0301-4797
    E-ISSN: 1095-8630
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  • 9
    In: Der Donauraum, 01/1/2012, Vol.52(2)
    ISSN: 0012-5415
    E-ISSN: 2307-289X
    Source: CrossRef
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  • 10
    Language: English
    In: Geoderma, Dec, 2011, Vol.169, p.1(3)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.geoderma.2011.07.021 Byline: Daniel Tunega, Martin H. Gerzabek, Kai U. Totsche Article History: Received 16 May 2011; Revised 3 July 2011; Accepted 23 July 2011
    Keywords: Soils -- Models
    ISSN: 0016-7061
    Source: Cengage Learning, Inc.
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