Search Results - (Author, Cooperation:M. Kleber)
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1Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2015-11-26Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Agriculture ; Carbon Cycle ; Crops, Agricultural/metabolism ; Ecosystem ; Humic Substances/*analysis ; Soil/*chemistry ; Water/chemistryPublished by: -
2Latest Papers from Table of Contents or Articles in PressM. W. Schmidt ; M. S. Torn ; S. Abiven ; T. Dittmar ; G. Guggenberger ; I. A. Janssens ; M. Kleber ; I. Kogel-Knabner ; J. Lehmann ; D. A. Manning ; P. Nannipieri ; D. P. Rasse ; S. Weiner ; S. E. Trumbore
Nature Publishing Group (NPG)
Published 2011Staff ViewPublication Date: 2011-10-08Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Bioengineering ; Carbon/*metabolism ; *Carbon Cycle ; Charcoal/metabolism ; Climate Change ; *Ecosystem ; Freezing ; Organic Chemicals/*analysis/metabolism ; Plant Roots/metabolism ; Plants/metabolism ; Soil/*chemistry ; Soil MicrobiologyPublished by: -
3Articles: DFG German National LicensesKleber, M. ; Mertz, C. ; Zikeli, S. ; Knicker, H. ; Jahn, R.
Oxford, UK; Malden, USA : Blackwell Science Ltd
Published 2004Staff ViewISSN: 1365-2389Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: GeosciencesAgriculture, Forestry, Horticulture, Fishery, Domestic Science, NutritionNotes: Preservation of organic matter in soils depends on the chemical structure of organic compounds and on the surface properties of the mineral matrix. We tested the effect of mineral surface reactivity on organic matter decomposition by (i) investigating changes of organic matter composition in clay subfractions of an illitic Haplic Chernozem along a time series of fertilizer deprivation and (ii) simultaneously characterizing the reactivity of mineral surfaces. The soil was subjected to fertilizer deprivation for 18, 44 and 98 years, respectively. Mineral surface properties were characterized by selective dissolution of pedogenic oxides. The number of hydroxyls released after exposure to sodium fluoride was taken as an index for mineral surface reactivity. Organic soil constituents were determined by 13C cross-polarization magic-angle spinning nuclear magnetic resonance (13C CPMAS NMR).Clay subfractions had different mineral surface properties. The coarse fractions have more reactive surfaces and contain more organic carbon than the fine clay fractions. Mineral surface properties are constant over time and are not affected by fertilizer deprivation. Surface reactivity is a function of iron oxide density and controls carbon concentrations in the clay subfractions. Within the time frame of our investigation, alkyl C and aromatic C responded to the duration of fertilizer deprivation, but were indifferent to mineral surface reactivity. O–alkyl C seems to be protected by interactions with pedogenic oxides.Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesKleber, M. ; Mikutta, R. ; Torn, M. S. ; Jahn, R.
Oxford, UK; Malden, USA : Blackwell Science Ltd
Published 2005Staff ViewISSN: 1365-2389Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: GeosciencesAgriculture, Forestry, Horticulture, Fishery, Domestic Science, NutritionNotes: Soil minerals are known to influence the biological stability of soil organic matter (SOM). Our study aimed to relate properties of the mineral matrix to its ability to protect organic C against decomposition in acid soils. We used the amount of hydroxyl ions released after exposure to NaF solution to establish a reactivity gradient spanning 12 subsoil horizons collected from 10 different locations. The subsoil horizons represent six soil orders and diverse geological parent materials. Phyllosilicates were characterized by X-ray diffraction and pedogenic oxides by selective dissolution procedures. The organic carbon (C) remaining after chemical removal of an oxidizable fraction of SOM with NaOCl solution was taken to represent a stable organic carbon pool. Stable organic carbon was confirmed as older than bulk organic carbon by a smaller radiocarbon (14C) content after oxidation in all 12 soils. The amount of stable organic C did not depend on clay content or the content of dithionite–citrate-extractable Fe. The combination of oxalate-extractable Fe and Al explained the greatest amount of variation in stable organic C (R2 = 0.78). Our results suggest that in acid soils, organic matter is preferentially protected by interaction with poorly crystalline minerals represented by the oxalate-soluble Fe and Al fraction. This evidence suggests that ligand exchange between mineral surface hydroxyl groups and negatively charged organic functional groups is a quantitatively important mechanism in the stabilization of SOM in acid soils. The results imply a finite stabilization capacity of soil minerals for organic matter, limited by the area density of reactive surface sites.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesSiregar, A. ; Kleber, M. ; Mikutta, R. ; Jahn, R.
Oxford, UK; Malden, USA : Blackwell Science Ltd
Published 2005Staff ViewISSN: 1365-2389Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: GeosciencesAgriculture, Forestry, Horticulture, Fishery, Domestic Science, NutritionNotes: Oxidative treatment can isolate a stable organic matter pool in soils for process studies of organic matter stabilization. Wet oxidation methods using hydrogen peroxide are widely used for that purpose, but are said to modify poorly crystalline soil constituents. We investigated the effect of a modified NaOCl oxidation (pH 8) on the mineral composition of 12 subsoils (4.9–38.2 g organic C kg−1) containing varying amounts of poorly crystalline mineral phases, i.e. 1.1–20.5 g oxalate-extractable Fe kg−1, and of different phyllosilicate mineralogy. Post-oxidative changes in mineral composition were estimated by (i) the determination of elements released into the NaOCl solution, (ii) the difference in dithionite- and oxalate-extractable Si, Al and Fe, and (iii) the specific surface areas (SSAs) of the soils. The NaOCl procedure reduced the organic C concentrations by 12–72%. The amounts of elements released into the NaOCl extracts were small (≤ 0.14 g kg−1 for Si, ≤ 0.13 g kg−1 for Al, and ≤ 0.03 g kg−1 for Fe). The SSA data and the amounts of dithionite- and oxalate-extractable elements suggest that the NaOCl oxidation at pH 8 does not attack pedogenic oxides and hydroxides and only slightly dissolves Al from the poorly crystalline minerals. Therefore, we recommend NaOCl oxidation at pH 8 for the purpose of isolating a stable organic matter pool in soils for process studies of organic matter stabilization.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1365-2389Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: GeosciencesAgriculture, Forestry, Horticulture, Fishery, Domestic Science, NutritionNotes: We used the specific surface area (SSA), the cation exchange capacity (CEC) and the content of dithionite-extractable iron (Fed) to predict the content of organic carbon in illitic clay fractions of topsoils from loess. We determined SSA (BET-N2 method) and CEC of clay fractions after removing organic C or reducing oxides or both. The CEC and the SSA of the carbon- and oxide-free clay fraction explained 56% and 54% of the variation in C content, respectively. The Fed content of the clay fractions was strongly and negatively related to the C content, and with the SSA of the carbon-free clay fraction it predicted C content almost completely (R2 = 0.96). The results indicate that the amount of cations adhering to the silicate clay minerals and the size of the silicate mineral surface area are important properties of the mineral phase for the storage potential of C. The reason for the negative relation between iron oxides and C content remains unclear.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 0375-9474Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesStaff View
ISSN: 0167-2789Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesStaff View
ISSN: 0168-583XSource: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesStaff View
ISSN: 0370-2693Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesStaff View
ISSN: 0370-1573Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesStaff View
ISSN: 0370-2693Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesStaff View
ISSN: 0370-2693Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesStaff View
ISSN: 0370-2693Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The Schrödinger equation is studied in a finite subspace of the Hilbert space. The truncation of the configuration space makes the (effective) interaction energy-dependent. This dependency is investigated. An analytic expression for the matrix elements of the effective interaction is established for the schematic model, for the displaced harmonic oscillator, for a simple random-phase problem and for a pairing force model. Thereby the phase transitions from bound to unbound states and from normal to superconducting states are analysed.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We investigate bremsstrahlung processes induced by heavy ions: nuclear dipole and quadrupole radiation, radiation from bound target electrons into the continuum and secondary electron bremsstrahlung (SEB), which contribute to the background of the X-ray spectra. A comparison with experiment is presented.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We derive self-consistent equations for polarization and binding of inner-shell electrons during ion-atom collisions. No restriction is made in the collision velocity. In particular, we study the effect of recoil in close encounters. The parameter-free calculations are in excellent agreement with experimental ionization probabilities.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We calculate the twist given to theπ-electrons of a benzene-like ring molecule when a magnetic monopole passes through the ring. As a result, we obtain an almost geometrical cross section for transferring the angular momentumħ to eachπ-electron. The possibility of using organic ring molecules as a monopole detector is discussed.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The RPA method is applied to two kinds of Hamiltonians. First the pairing force Hamiltonian for two levels is considered. The RPA ground state energy lies below the actual energy whereas the RPA excitation energies are too small. In the case of a more realistic Hamiltonian a potential strength is chosen for which the RPA reproduces the 6.06 MeV 0+ level of O16. By comparison with the (variational) FBCS approximation it is seen that the RPA ground state energy again lies considerably below the variational value. The RPA ground state wave function is calculated. It is shown that the quasi-boson approach of the RPA enhances the spread of the fermi level. The enhancement is proved to become singular when the RPA breaks down. Finally, the class of possible RPA ground state wave functions is discussed.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The Tamm-Dancoff approximation is applied to the correlated FBCS ground state. This procedure proves very successful for medium and heavy nuclei both superconducting and non-superconducting. The accuracy of the Tamm-Dancoff approximation is equivalent to forth order boson methods. Calculations have been performed for the nickel isotopes, for Sn114 and for the lead isotopes. The connection with the broken-pair approximation is established. The influence of a nucleus withN−2 nucleons on the spectrum of a nucleus withN particles is exhibited.Type of Medium: Electronic ResourceURL: