Research Projects

DFG

  • Soil manganese: Speciation, transformation, and reactivity
    Led by: Prof. Dr. Christian Mikutta
    Team: M. Sc. Teresa Zahoransky
    Year: 2018
    Funding: DFG
    Duration: 2018-2021
  • Aluminum interactions with iron oxides in the absence and presence of silicic acid
    Led by: Prof. Dr. Christian Mikutta, Prof. Dr. Robert Mikutta (Martin-Luther-Universität Halle-Wittenberg)
    Team: M. Sc. Svenja Heimann
    Year: 2018
    Funding: DFG
    Duration: 2018-2021
  • Natural organic matter control on silicate interactions with iron oxides and silicon phytoavailability
    Led by: Robert Mikutta, Anika Klotzbücher, Thimo Klotzbücher, Klaus Kaiser (Martin-Luther-Universität Halle-Wittenberg), Christian Mikutta (Leibniz Universität Hannover
    Team: Jana Dobritzsch
    Year: 2019
    Funding: DFG
    Duration: 2019-2022
  • Effects of redox oscillations on soil clay mineralogy and colloid dynamics
    Led by: Prof. Dr. Christian Mikutta , Dr. Reiner Dohrmann (Bundesanstalt für Geowissenschaften und Rohstoffe)
    Team: M. Sc. Max Niegisch
    Year: 2019
    Funding: DFG
    Duration: 2019-2022
  • Formation and properties of mineral-organic soil interfaces as revealed by X-ray photoelectron spectroscopy
    Led by: Robert Mikutta, Thimo Klotzbücher, Klaus Kaiser (Martin-Luther-Universität Halle-Wittenberg), Christian Mikutta (Leibniz Universität Hannover)
    Team: Thimo Klotzbücher
    Year: 2019
    Funding: DFG
    Duration: 2019-2022
  • Molecular-scale mechanisms of antimony binding to soil organic matter
    Led by: Prof. Dr. Christian Mikutta
    Team: M. Sc. Sascha Wilke
    Year: 2019
    Funding: DFG
    Duration: 2019-2022
  • Interactions between manganese oxides and dissolved organic matter in soil
    Led by: Prof. Dr. Christian Mikutta, Dr. Ricarda Behrens (Leibniz Universität Hannover), Robert Mikutta, Klaus Kaiser (Martin-Luther-Universität Halle-Wittenberg)
    Team: M. Sc. Lena Brüggenwirth
    Year: 2019
    Funding: DFG
    Duration: 2019-2022
  • Mineral surfaces as hotspots for microbes and element cycling in the Biodiversity Exploratories (BEmins)
    Led by: Marion Schrumpf (Max-Planck-Institut für Biogeochemie), Ellen Kandeler (Universität Hohenheim), Klaus Kaiser, Robert Mikutta (Martin-Luther-Universität Halle-Wittenberg), Christian Mikutta (Leibniz Universität Hannover)
    Team: Katja Pursche
    Year: 2020
    Funding: DFG
    Duration: 2020-2023
  • Abundance and composition of inorganic X-ray amorphous materials in soils
    "X-ray amorphous" solids are characterized by extremely small crystal sizes, pronounced lattice distortions or atomic short-range order. In comparison to crystalline solids, "X-ray amorphous" solids possess diffuse X-ray diffraction patterns and thus remain "visible" as elevated signal background in X-ray diffractograms. In soils, inorganic X-ray amorphous materials (iXAMs) exist as vitreous phases, minerals whose crystals have too few repeating structural units to diffract X-rays ("poorly crystalline" or "nanocrystalline" minerals), and solids of variable chemical composition possessing exclusively atomic short-range order ("mineraloids"). Due to their large specific surface areas and reactive surface groups, iXAMs control important soil processes such as carbon turnover, mineral weathering, and sorption reactions of nutrients and pollutants. Despite their ecological significance, soil iXAMs are still poorly understood. Knowledge gaps exist particularly with regard to their nature, total contents, chemical composition, and distribution in soils as well as their quantifiability using wet chemical extraction methods. To fill these knowledge gaps, we quantify iXAMs in the fine earth (<2 mm) and in particle-size fractions of four soil types (Cambisol, Chernozem, Luvisol, Podsol) by quantitative X-ray diffraction (Rietveld method). The chemical composition of the iXAMs is determined by mass balances based on the Rietveld results and chemical analyses of the soil samples ("balance sheet method"). On this basis, we investigate the suitability of common selective extraction methods for the determination of "X-ray amorphous" soil solids to quantitatively determine their absolute contents and chemical composition in soils. In addition, we explore the nature and composition of iXAMs (<1 µm) from selected particle-size fractions using analytical transmission electron microscopy. Overall, the research project provides basic information (1) on total iXAM contents in soils, their nature and chemical composition as well as depth-dependent distribution and (2) on the quantification of iXAMs by selective extraction methods. Thus, this project forms the basis for a detailed investigation of the influence of iXAMs on soil functions and properties in the future.
    Led by: Professor Dr. Christian Mikutta (LUH), Dr. Reiner Dohrmann (BGR)
    Team: M. Sc. Sileola Joseph Akinbodunse
    Year: 2021
    Funding: DFG
    Duration: 2021-2023