18. Global biogeochemical cycling of elements 18.1 Biogeochemistry Time scales: Precambrian chemistry begins about at 4.6 eons (Gigayears ago); precambrian biology begins about 3.8 Gy ago; stromatolites (most common precambrian fossils) 2.2-3.4 eons; first 2-dimensional animal 1.2 eons. Interactions between global cycles of carbon, sulfur, nitrogen, phosphorus, iron and manganese. Evolution of oxic photosynthesis. The role of microbes in Hadean to Proterozoic atmosphere and hydrosphere evolution. 18.2 Atmosphere/biosphere interactions The role of climate oscillations on biological evolution: how was prokaryotic evolution affected ? How oxygenic phototrophs changed atmospheric chemistry globally. Microbial regulation of atmospheric gases (O2, CO2, CH4, N2, N2O, NOx, DMSO). The contribution of aerobic C-1 oxidizers to global budgets of atmospheric trace gases. 18.3 Solid-state microbiology How microbes interact with mineral surfaces: weathering, corrosion, leaching. Natural weathering agents of microbial origin. Disturbance of weathering processes by anthropogenic pollutants. Active and passive formation of biominerals: intracellular and extracellular magnetite, nucleation of crystal formation on cell surfaces and inside cells. Biologically mediated mineral dissolution: acid-base reactions, redox processes, ligand mediated reactions. Microbially mediated formation of hydroxyapatite in sediments: a thermodynamic case study. Geomicrobiology and crustal evolution, effects of volcanism, plate tectonics, eustatic sea-level change, glaciation (snowball earth). Clay surfaces as early bio-informatic templates. Ironsulfide crystals as templates and energy sources. 18.4 Carbon sinks and sources The microbe's role in "fossil fuel" formation, accumulation and cycling Tar pits as ecosystems The mobilization of methane clathrates 18.5 Prokaryotic extremophiles Microbes which make use of redox-labile heavy elements (As, Se, Cr, Cu, Mo, Sb, U, etc.) Microbes which thrive under extremes of pH, salinity and temperature Strategies to overcome nutrient deprivation: transport efficiency, remaining very small (nanobes) Not growth, but maintenance as survival strategy 18.6 Metal-microbe interactions Biosorption of metals Bioaccumulation Metal alkylation Metal solubilization mechanisms Industrial applications
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