TY - CHAP A1 - Lessovaia, S.N. A1 - Gerrits, Ruben A1 - Gorbushina, Anna A1 - Polekhovsky, Y.S. A1 - Dultz, S. A1 - Kopitsa, G.G. ED - Frank-Kamenetskaya, O.V. ED - Vlasov, D. ED - Panova, E.G. ED - Lessovaia, S.N. T1 - Modeling Biogenic Weathering of Rocks from Soils of Cold Environments T2 - Processes and Phenomena on the Boundary Between Biogenic and Abiogenic Nature N2 - Morphologically simple and microbially dominated ecosystems termed “biofilms” have existed on Earth for a long period of biosphere evolution. A model biofilm combining one heterotroph and one phototroph component was used in a laboratory experiment to simulate biogenic weathering with two different specimens of basic rock samples from the soil profiles. The rocks fragments from the regions of cold environments of Eurasia,where abiotic physical processes, including rock disintegration initiated by freezing–thawing cycles, represent the most probable Scenario of rock weathering, were subjected to biological colonization. The rock Fragments were represented by dolerite and metagabbro amphibolites. Polished sections of the rock samples were inoculated with the model microbiological consortium of the oligotrophic fungus and the phototrophic cyanobacteria (biofilm). After 3 month runtime of the experiment the progress of rock weathering was derived from the growth of the biofilm on the rock surfaces. The model biofilm visualization on the rock surface of polished sections illustrated their stronger development namely on dolerite in comparison with metagabbro amphibolite. The findings confirmed the higher sensitivity of dolerite to biogenic weathering due to (i) mineral association, in which quartz was absent and (ii) porosity providing higher specific surface area for biotic—abiotic interaction influenced by the occurrence of micro-porosity in the rock. KW - Biogenic weathering KW - Rock leaching KW - Fractal structure KW - Biofilm formation KW - Internal pores PY - 2020 DO - https://doi.org/10.1007/978-3-030-21614-6_27 SP - 501 EP - 515 PB - Springer AN - OPUS4-51442 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koester, M. A1 - Stock, S. C. A1 - Nájera, F. A1 - Abdallah, Khaled A1 - Gorbushina, Anna A1 - Prietzel, J. A1 - Matus, F. A1 - Klysubun, W. A1 - Boy, J. A1 - Kuzyakov, Y. A1 - Dippold, M. A. A1 - Spielvogel, S. T1 - From rock eating to vegetarian ecosystems — Disentangling processes of phosphorus acquisition across biomes JF - Geoderma N2 - Low-molecular-weight organic acids (LMWOAs) are crucial for the mobilization and acquisition of mineral phosphorus by plants. However, the role of LMWOAs in mobilizing organic phosphorus, which is the predominant phosphorus form in at least half of the world’s ecosystems, especially in humid climates, is unclear. The mechanisms of phosphorus mobilization by LMWOAs depend on climate, mainly precipitation, and shape the phosphorus nutrition strategies of plants. We disentangled the impact of roots and associated microorganisms on mechanisms of phosphorus cycling mediated by LMWOAs by studying soils along an ecosystem-sequence (ecosequence) from arid shrubland (~70 mm yr-1), and Mediterranean woodland (~370 mm yr-1) to humid-temperate forest (~1470 mm yr-1). Phosphorus speciation in soil was examined by X-ray absorption near edge structure analysis (XANES). LMWOAs were quantified as biological rock-weathering and organic phosphorus mobilization agents and compared to kinetics of acid phosphatase as a proxy for organic phosphorus mineralization. Calcium-bound phosphorus in topsoils decreased from 126 mg kg-1 in the arid shrubland, to 19 mg kg-1 in the Mediterranean woodland and was undetectable in the humid-temperate forest. In contrast, organic phosphorus in topsoils in close root proximity (0–2 mm distance to roots) was absent in the arid shrubland but raised to 220 mg kg-1 in the Mediterranean woodland and to 291 mg kg-1 in the humid-temperate forest. The organic phosphorus content in topsoils was 1.6 to 2.4 times higher in close root proximity (0–2 mm distance to roots) compared to bulk soil (4–6 mm distance to roots) in the Mediterranean woodland and humid-temperate forest, showing intensive phosphorus bioaccumulation in the rhizosphere. Redundancy analysis (RDA) revealed that LMWOAs were explained by the content of hydroxyapatite and variscite phosphorus-species in the arid shrubland, indicating that LMWOAs contribute to mineral weathering in this soil. LMWOA contents, phosphatase activity, and microbial biomass carbon correlated strongly with organic phosphorus in the humid-temperate forest soil, which implies a high relevance of LMWOAs for organic phosphorus recycling. In the Mediterranean woodland soil, however, oxalic acid correlated with organic phosphorus in the topsoil (suggesting phosphorus recycling), whereas in the subsoil malic and citric acid were correlated with primary and secondary phosphorus minerals (implying mineral weathering). We conclude that phosphorus acquisition and cycling depend strongly on climate and that the functions of LMWOAs in the rhizosphere change fundamentally along the precipitation gradient. In the arid shrubland LMWOAs facilitate biochemical weathering (rock eating), while in the humid-temperate forest their functions change towards supporting organic phosphorus recycling (vegetarian). KW - Rhizosphere processes KW - Phosphorus K-edge-XANES spectroscopy KW - Low-molecular-weight organic substances KW - Organic phosphorus breakdown KW - Biogenic weathering KW - Climate gradient PY - 2020 DO - https://doi.org/10.1016/j.geoderma.2020.114827 VL - 388 SP - 114827 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-51931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -