TY - CHAP A1 - Krumbein, W.E. A1 - Gorbushina, Anna ED - Timmis, K.N. T1 - Global relations between the Redox cycles of carbon, iron, and sulfur N2 - Solar energy has been transformed into useful redox differences or disequilibria within the Earth´s crust since the onset of anoxygenic and oxygenic photosynthesis in the Precambrian. Inorganic oxidized carbon is transformed into reduced carbon compounds by capturing and storing solar energy. During this process, many different organic compounds are formed including carbohydrates, proteins, hydrocarbons, and various other complex organic metabolic products and their diagenetic polymerization products (melanin, humic substances, petroleum, coal, and kerogen). Many of these solar energy-enriched compounds, however, are oxidized immediately or during the diagenetic transformation of sediments. The oxidation agents are oxygen, sulfate, iron, and other oxidized compounds, which in turn are partly enriched with the original solar energy. On a global biogeochemical scale, however, sulfur and iron are the most important elements. Geological evidence shows that biogeochemical cycles tend to yield stable ratios between the most oxidized forms of carbon (carbon dioxide and calcium/magnesium carbonate) and the most reduced forms (diamond, coal, methane, and hydrocarbons). Throughout the Earth’s history and evolution, this equilibrium ratio is around 1:4, maximally 1:5. When too much carbon is stored in the crust in the form of reduced compounds or vice versa, climatic and biogeomorphogenetic consequences upset the equilibrium. The biosphere reacts in a way to return to the optimal ratio. Excellent examples for this fluctuating equilibrium are the Carboniferous (too much organic carbon stored), the Permian (too little organic carbon stored), and the Tertiary with a generally equivalent production of hydrocarbons and carbonates. At present, we are in a period in which there is a global biogeochemical need to oxidize reduced carbon compounds as fast as possible in order to avoid even more dramatic global climate shifts. The highly evolved human genome seems to be the tool for this shift. Enormous amounts of reduced carbon are turned into the oxidized form as carbon dioxide, which by various biogeochemical pathways is quickly transformed into carbonate, another oxidized form of carbon that can be stabilized and stored in the sedimentary record. Fast recycling of excessively stored solar energy may enable the survival of a global biosphere under highly stressed conditions. KW - Geochemistry KW - Biologically influenced mineral fluxes PY - 2010 SN - 978-3-540-77584-3 SN - 978-3-540-77587-4 U6 - https://doi.org/10.1007/978-3-540-77587-4_10 IS - Chapter 10 SP - 157 EP - 169 PB - Springer CY - Berlin Heidelberg AN - OPUS4-21983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -