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The carbon cycle is a part of the biogeochemical cycle where carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth.Other major biogeochemical cycles include the nitrogen cycle and the water cycle.
The reverse Krebs cycle, also known as the reverse TCA cycle (rTCA) or reductive citric acid cycle, is an alternative to the standard Calvin-Benson cycle for carbon fixation. It has been found in strict anaerobic or microaerobic bacteria (as Aquificales ) and anaerobic archea .
The carbon cycle is a biogeochemical cycle that is important in maintaining life on Earth over a long time span. The cycle includes carbon sequestration and carbon sinks . [ 4 ] [ 5 ] Plate tectonics are needed for life over a long time span, and carbon-based life is important in the plate tectonics process. [ 6 ]
Anaerobic respiration is a critical component of the global nitrogen, iron, sulfur, and carbon cycles through the reduction of the oxyanions of nitrogen, sulfur, and carbon to more-reduced compounds. The biogeochemical cycling of these compounds, which depends upon anaerobic respiration, significantly impacts the carbon cycle and global warming ...
Carbon storage in the biosphere is influenced by a number of processes on different time-scales: while carbon uptake through autotrophic respiration follows a diurnal and seasonal cycle, carbon can be stored in the terrestrial biosphere for up to several centuries, e.g. in wood or soil. Most carbon leaves the terrestrial biosphere through ...
The carbon cycle of a terrestrial ecosystem. [6] Beginning with photosynthesis, water (blue) and carbon dioxide (white) from the air are taken in with solar energy (yellow), and are converted into plant energy (green). [7] 100×10 15 grams of carbon/year fixed by photosynthetic organisms, which is equivalent to 4×10 18 kJ/yr = 4×10 21 J/yr of ...
A photon with an energy near a semiconductor band gap has almost zero momentum. One important process is called radiative recombination, where an electron in the conduction band annihilates a hole in the valence band, releasing the excess energy as a photon. This is possible in a direct band gap semiconductor if the electron has a k-vector near ...
The majority of known chemical cycles on Venus involve its dense atmosphere and compounds of carbon and sulphur, the most significant being a strong carbon dioxide cycle. [3] The lack of a complete carbon cycle including a geochemical carbon cycle, for example, is thought to be a cause of its runaway greenhouse effect, due to the lack of a ...