HR: 1340h
AN: H43C-1514    [Abstracts]
TI: Biologically-Mediated Weathering of Minerals From Nanometre Scale to Environmental Systems
AU: * Brown, D J
EM: d.j.brown@sheffield.ac.uk
AF: Department of Civil and Structural Engineering, University of Sheffield, Kroto Research Institute, North Campus, Broad Lane, Sheffield, S3 7HQ, United Kingdom
AU: Banwart, S A
EM: s.a.banwart@sheffield.ac.uk
AF: Department of Civil and Structural Engineering, University of Sheffield, Kroto Research Institute, North Campus, Broad Lane, Sheffield, S3 7HQ, United Kingdom
AU: Smits, M M
EM: m.smits@sheffield.ac.uk
AF: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, United Kingdom
AU: Leake, J R
EM: j.r.leake@sheffield.ac.uk
AF: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, United Kingdom
AU: Bonneville, S
EM: s.bonneville@see.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Earth Science Building, Leeds, LS2 9JT, United Kingdom
AU: Benning, L G
EM: liane@see.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Earth Science Building, Leeds, LS2 9JT, United Kingdom
AU: Haward, S J
EM: s.j.haward@bristol.ac.uk
AF: Department of Physics, University of Bristol, H. H. Wills Physics Lab, Tyndell Avenue, Bristol, BS8 1TL, United Kingdom
AU: Ragnarsdottir, K
EM: vala.ragnarsdottir@bris.ac.uk
AF: Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 1RJ, United Kingdom
AB: The Weathering Science Consortium is a multi-disciplinary project that aims to create a step change in understanding how biota control mineral weathering and soil formation (http://www.wun.ac.uk/wsc). Our hypothesis is that rates of biotic weathering are driven by the energy supply from plants to the organisms, controlling their biomass, surface area of contact with minerals and their capacity to interact chemically with minerals. Symbiotic fungal mycorrhiza of 90% of plant species are empowered with an available carbohydrate supply from plants that is unparalleled amongst soil microbes. They develop extensive mycelial networks that intimately contact minerals, which they weather aggressively. We hypothesise that mycorrhiza play a critical role through their focussing of photosynthate energy from plants into sub-surface weathering environments. Our work identifies how these fungal cells, and their secretions, interact with mineral surfaces and affect the rates of nutrient transfer from minerals to the organism. Investigating these living systems allows us to create new concepts and mathematical models that can describe biological weathering and be used in computer simulations of soil weathering dynamics. We are studying these biochemical interactions at 3 levels of observation: 1. At the molecular scale to understand interactions between living cells and minerals and to quantify the chemistry that breaks down the mineral structure; 2. At the soil grain scale to quantify the activity and spatial distribution of the fungi, roots and other organisms (e.g. bacteria) and their effects on the rates at which minerals are dissolved to release nutrients; 3. At soil profile scale to test models for the spatial distribution of active fungi and carbon energy and their seasonal variability and impact on mineral dissolution rates. Here we present early results from molecular and soil grain scale experiments. We have grown pure culture (Suillus bovinus, Paxillus involutus) mycorrhizal mycelial networks associated with pine trees in otherwise sterile (agar) and also non-sterile (peat) microcosms, which include mineral sections and powders of biotite, apatite and quartz. ¹⁴C labelling has been used to map C flux through the microcosms and to determine the transfer of photosynthate energy into the weathering arenas. We have used Vertical Scanning Interferometry (VSI) to assess volumetric alteration of mineral substrates in contact with fungi. Focused Ion Beam (FIB)- Transmission Electron Microscope (TEM) work provides evidence for increased mechanical forcing and possible alteration of biotite surfaces with greater fungi contact time. We also present real-time in situ observations of mineral-organic acid and mineral-exudate interactions using Atomic Force Microscopy (AFM).
UR: http://www.wun.ac.uk/wsc
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0463 Microbe/mineral interactions
DE: 1865 Soils (0486)
DE: 1886 Weathering (0790, 1625)
SC: Hydrology [H]
MN: 2007 Fall Meeting