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74-404: Rødsand I was built in 2003, with 72 turbines and a total capacity of 166 MW, and was the largest in the world until 2007. Annual production is some 570 GW·h, the equivalent to the electricity consumption of 140,000 Danish homes, which could save 500,000 tonnes of CO 2 emissions. Turbines were installed by A2SEA . It receives 45 øre per kW·h for the first 42,000 full-load hours, which

148-516: A decline in basic activity level and information usage at 1000 ppm, when compared to 500 ppm. However a review of the literature found that a reliable subset of studies on the phenomenon of carbon dioxide induced cognitive impairment to only show a small effect on high-level decision making (for concentrations below 5000 ppm). Most of the studies were confounded by inadequate study designs, environmental comfort, uncertainties in exposure doses and differing cognitive assessments used. Similarly

222-446: A fixed structure. However, in a Coulomb explosion imaging experiment, an instantaneous image of the molecular structure can be deduced. Such an experiment has been performed for carbon dioxide. The result of this experiment, and the conclusion of theoretical calculations based on an ab initio potential energy surface of the molecule, is that none of the molecules in the gas phase are ever exactly linear. This counter-intuitive result

296-611: A glass state similar to other members of its elemental family, like silicon dioxide (silica glass) and germanium dioxide . Unlike silica and germania glasses, however, carbonia glass is not stable at normal pressures and reverts to gas when pressure is released. At temperatures and pressures above the critical point, carbon dioxide behaves as a supercritical fluid known as supercritical carbon dioxide . Table of thermal and physical properties of saturated liquid carbon dioxide: Table of thermal and physical properties of carbon dioxide (CO 2 ) at atmospheric pressure: Carbon dioxide

370-491: A mature forest will produce as much CO 2 from respiration and decomposition of dead specimens (e.g., fallen branches) as is used in photosynthesis in growing plants. Contrary to the long-standing view that they are carbon neutral, mature forests can continue to accumulate carbon and remain valuable carbon sinks , helping to maintain the carbon balance of Earth's atmosphere. Additionally, and crucially to life on earth, photosynthesis by phytoplankton consumes dissolved CO 2 in

444-428: A much larger denominator and a much smaller value than the true K a1 . The bicarbonate ion is an amphoteric species that can act as an acid or as a base, depending on pH of the solution. At high pH, it dissociates significantly into the carbonate ion ( CO 2− 3 ): In organisms, carbonic acid production is catalysed by the enzyme known as carbonic anhydrase . In addition to altering its acidity,

518-432: A process carried out by a diverse community of microorganisms. During decomposition, complex organic compounds are broken down into simpler molecules by the action of enzymes produced by bacteria, fungi, and other soil organisms. As organic matter is decomposed, carbon is released in various forms, including carbon dioxide (CO2) and dissolved organic carbon (DOC). However, not all of the carbon released during decomposition

592-426: A share. As of 2013 it has an availability of 97 percent. In 2010, a 207 MW extension of the existing wind farm was installed by E.ON at a stated cost of EUR450m and a power purchase agreement at DKK 0.629 per kW·h (US$ 0.12/kW·h). It was originally scheduled to be completed in 2011, but installation happened faster than projected, and on 15 July 2010, E.ON reported that all turbines had been installed and

666-416: A study on the effects of the concentration of CO 2 in motorcycle helmets has been criticized for having dubious methodology in not noting the self-reports of motorcycle riders and taking measurements using mannequins. Further when normal motorcycle conditions were achieved (such as highway or city speeds) or the visor was raised the concentration of CO 2 declined to safe levels (0.2%). Poor ventilation

740-467: A typical single C–O bond, and shorter than most other C–O multiply bonded functional groups such as carbonyls . Since it is centrosymmetric, the molecule has no electric dipole moment . As a linear triatomic molecule, CO 2 has four vibrational modes as shown in the diagram. In the symmetric and the antisymmetric stretching modes, the atoms move along the axis of the molecule. There are two bending modes, which are degenerate , meaning that they have

814-485: A waste product. In turn, oxygen is consumed and CO 2 is released as waste by all aerobic organisms when they metabolize organic compounds to produce energy by respiration . CO 2 is released from organic materials when they decay or combust, such as in forest fires. When carbon dioxide dissolves in water, it forms carbonate and mainly bicarbonate ( HCO − 3 ), which causes ocean acidification as atmospheric CO 2 levels increase. Carbon dioxide

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888-469: Is Emiliania huxleyi whose calcite scales have formed the basis of many sedimentary rocks such as limestone , where what was previously atmospheric carbon can remain fixed for geological timescales. Plants can grow as much as 50% faster in concentrations of 1,000 ppm CO 2 when compared with ambient conditions, though this assumes no change in climate and no limitation on other nutrients. Elevated CO 2 levels cause increased growth reflected in

962-443: Is glyceraldehyde 3-phosphate (GAP) together with dihydroxyacetone phosphate (DHAP): An alternative perspective accounts for NADPH (source of e ) and ATP: The formula for inorganic phosphate (P i ) is HOPO 3 + 2H . Formulas for triose and TP are C 2 H 3 O 2 -CH 2 OH and C 2 H 3 O 2 -CH 2 OPO 3 + 2H The reverse Krebs cycle , also known as the reverse TCA cycle (rTCA) or reductive citric acid cycle ,

1036-419: Is 304.128(15) K (30.978(15) °C) at 7.3773(30) MPa (72.808(30) atm). Another form of solid carbon dioxide observed at high pressure is an amorphous glass-like solid. This form of glass, called carbonia , is produced by supercooling heated CO 2 at extreme pressures (40–48  GPa , or about 400,000 atmospheres) in a diamond anvil . This discovery confirmed the theory that carbon dioxide could exist in

1110-569: Is 53% more dense than dry air, but is long lived and thoroughly mixes in the atmosphere. About half of excess CO 2 emissions to the atmosphere are absorbed by land and ocean carbon sinks . These sinks can become saturated and are volatile, as decay and wildfires result in the CO 2 being released back into the atmosphere. CO 2 is eventually sequestered (stored for the long term) in rocks and organic deposits like coal , petroleum and natural gas . Nearly all CO2 produced by humans goes into

1184-406: Is a chemical compound with the chemical formula CO 2 . It is made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature and at normally-encountered concentrations it is odorless. As the source of carbon in the carbon cycle , atmospheric CO 2 is the primary carbon source for life on Earth. In

1258-440: Is a very expensive pathway: 7 ATP molecules are used for the synthesis of the new pyruvate and 3 ATP for the phosphate triose. An important characteristic of this cycle is that it allows the co-assimilation of numerous compounds making it suitable for the mixotrophic organisms. A variant of the 3-hydroxypropionate cycle was found to operate in the aerobic extreme thermoacidophile archaeon Metallosphaera sedula . This pathway

1332-492: Is about 11 years. Rødsand I was out for 4 1 ⁄ 2 months in 2007 when the main transformer suffered a malfunction, causing a production loss of 23 million DKK per month. In September 2010, DONG bought E.ON's 20% share and sold half of the entire project to pension fund PensionDanmark for 700 million kroner (€94 million / US$ 120 million) — almost half the DKK1,600 million cost. Stadtwerke Lübeck also owns

1406-400: 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 . It was discovered by Evans, Buchanan and Arnon in 1966 working with the photosynthetic green sulfur bacterium Chlorobium limicola . In particular, it is one of the most used pathways in hydrothermal vents by

1480-415: Is an end product of cellular respiration in organisms that obtain energy by breaking down sugars, fats and amino acids with oxygen as part of their metabolism . This includes all plants, algae and animals and aerobic fungi and bacteria. In vertebrates , the carbon dioxide travels in the blood from the body's tissues to the skin (e.g., amphibians ) or the gills (e.g., fish ), from where it dissolves in

1554-462: Is called the 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) cycle. Yet another variant of the 3-hydroxypropionate cycle is the dicarboxylate/4-hydroxybutyrate (DC/4-HB) cycle. It was discovered in anaerobic archaea. It was proposed in 2008 for the hyperthermophile archeon Ignicoccus hospitalis . CO 2 fixation is catalyzed by enoyl-CoA carboxylases/reductases. Although no heterotrophs use carbon dioxide in biosynthesis, some carbon dioxide

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1628-465: Is carbon dioxide (CO 2 ). It is estimated that approximately 250 billion tons of carbon dioxide are converted by photosynthesis annually. The majority of the fixation occurs in terrestrial environments, especially the tropics. The gross amount of carbon dioxide fixed is much larger since approximately 40% is consumed by respiration following photosynthesis. Historically, it is estimated that approximately 2×10 billion tons of carbon has been fixed since

1702-402: Is commercially used in its solid form, commonly known as " dry ice ". The solid-to-gas phase transition occurs at 194.7 Kelvin and is called sublimation . The symmetry of a carbon dioxide molecule is linear and centrosymmetric at its equilibrium geometry. The length of the carbon–oxygen bond in carbon dioxide is 116.3  pm , noticeably shorter than the roughly 140 pm length of

1776-481: Is composed of two cycles and the name of this way comes from the 3-Hydroxyporopionate which corresponds to an intermediate characteristic of it. The first cycle is a way of synthesis of glyoxylate . During this cycle, two equivalents of bicarbonate are fixed by the action of two enzymes: the Acetyl-CoA carboxylase catalyzes the carboxylation of the Acetyl-CoA to Malonyl-CoA and Propionyl-CoA carboxylase catalyses

1850-560: Is cyclic due to the regeneration of the oxaloacetate. The bacteria Gammaproteobacteria and Riftia pachyptila switch from the Calvin-Benson cycle to the rTCA cycle in response to concentrations of H 2 S . The reductive acetyl CoA pathway (CoA) pathway, also known as the Wood-Ljungdahl pathway uses CO 2 as electron acceptor and carbon source, and H 2 as an electron donor to form acetic acid. This metabolism

1924-459: Is immediately lost to the atmosphere; a significant portion is retained in the soil through processes collectively known as soil carbon sequestration. Soil microbes, particularly bacteria and fungi, play a pivotal role in this process by incorporating decomposed organic carbon into their biomass or by facilitating the formation of stable organic compounds, such as humus and soil organic matter. One key mechanism by which soil microbes sequester carbon

1998-455: Is incorporated in their metabolism. Notably pyruvate carboxylase consumes carbon dioxide (as bicarbonate ions) as part of gluconeogenesis , and carbon dioxide is consumed in various anaplerotic reactions . 6-phosphogluconate dehydrogenase catalyzes the reductive carboxylation of ribulose 5-phosphate to 6-phosphogluconate in E. coli under elevated CO 2 concentrations. Some carboxylases , particularly RuBisCO , preferentially bind

2072-632: Is one of the main causes of excessive CO 2 concentrations in closed spaces, leading to poor indoor air quality . Carbon dioxide differential above outdoor concentrations at steady state conditions (when the occupancy and ventilation system operation are sufficiently long that CO 2 concentration has stabilized) are sometimes used to estimate ventilation rates per person. Higher CO 2 concentrations are associated with occupant health, comfort and performance degradation. ASHRAE Standard 62.1–2007 ventilation rates may result in indoor concentrations up to 2,100 ppm above ambient outdoor conditions. Thus if

2146-452: Is only found in certain archaea and accounts for 80% of global methanogenesis, is also based on the reductive acetyl CoA pathway. The Carbon Monoxide Dehydrogenase / Acetyl-CoA Synthase is the oxygen-sensitive enzyme that permits the reduction of CO 2 to CO and the synthesis of acetyl-CoA in several reactions. One branch of this pathway, the methyl branch, is similar but non-homologous between bacteria and archaea. In this branch happens

2220-410: Is ordinarily a difficult and slow reaction: The redox potential for this reaction near pH 7 is about −0.53 V versus the standard hydrogen electrode . The nickel-containing enzyme carbon monoxide dehydrogenase catalyses this process. Photoautotrophs (i.e. plants and cyanobacteria ) use the energy contained in sunlight to photosynthesize simple sugars from CO 2 absorbed from

2294-508: Is primarily fixed through photosynthesis , but some organisms use chemosynthesis in the absence of sunlight . Chemosynthesis is carbon fixation driven by chemical energy rather than from sunlight.   The process of biological carbon fixation plays a crucial role in the global carbon cycle, as it serves as the primary mechanism for removing CO 2 (carbon dioxide) from the atmosphere and incorporating it into living biomass. The primary production of organic compounds allows carbon to enter

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2368-405: Is produced as a by-product. Ribulose-1,5-bisphosphate carboxylase oxygenase , commonly abbreviated to RuBisCO, is the enzyme involved in the first major step of carbon fixation, the production of two molecules of 3-phosphoglycerate from CO 2 and ribulose bisphosphate , as shown in the diagram at left. RuBisCO is thought to be the single most abundant protein on Earth. Phototrophs use

2442-472: Is the true first acid dissociation constant, defined as where the denominator includes only covalently bound H 2 CO 3 and does not include hydrated CO 2 (aq). The much smaller and often-quoted value near 4.16 × 10 (or pK a1 = 6.38) is an apparent value calculated on the (incorrect) assumption that all dissolved CO 2 is present as carbonic acid, so that Since most of the dissolved CO 2 remains as CO 2 molecules, K a1 (apparent) has

2516-555: Is the main cause of these increased CO 2 concentrations, which are the primary cause of climate change . Its concentration in Earth's pre-industrial atmosphere since late in the Precambrian was regulated by organisms and geological features. Plants , algae and cyanobacteria use energy from sunlight to synthesize carbohydrates from carbon dioxide and water in a process called photosynthesis , which produces oxygen as

2590-407: Is through the process of microbial biomass production. Bacteria and fungi assimilate carbon from decomposed organic matter into their cellular structures as they grow and reproduce. This microbial biomass serves as a reservoir for stored carbon in the soil, effectively sequestering carbon from the atmosphere. Additionally, soil microbes contribute to the formation of stable soil organic matter through

2664-419: Is trivially due to the fact that the nuclear motion volume element vanishes for linear geometries. This is so for all molecules except diatomic molecules . Carbon dioxide is soluble in water, in which it reversibly forms H 2 CO 3 (carbonic acid), which is a weak acid , because its ionization in water is incomplete. The hydration equilibrium constant of carbonic acid is, at 25 °C: Hence,

2738-465: Is used in CO 2 scrubbers and has been suggested as a possible starting point for carbon capture and storage by amine gas treating . Only very strong nucleophiles, like the carbanions provided by Grignard reagents and organolithium compounds react with CO 2 to give carboxylates : In metal carbon dioxide complexes , CO 2 serves as a ligand , which can facilitate the conversion of CO 2 to other chemicals. The reduction of CO 2 to CO

2812-537: Is wide spread within the phylum Bacillota , especially in the Clostridia . The pathway is also used by methanogens , which are mainly Euryarchaeota , and several anaerobic chemolithoautotrophs, such as sulfate-reducing bacteria and archaea. It is probably performed also by the Brocadiales, an order of Planctomycetota that oxidize ammonia in anaerobic condition. Hydrogenotrophic methanogenesis , which

2886-596: The Calvin cycle or the reductive citric acid cycle. The Calvin cycle accounts for 90% of biological carbon fixation. Consuming adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH), the Calvin cycle in plants accounts for the predominance of carbon fixation on land. In algae and cyanobacteria, it accounts for the dominance of carbon fixation in the oceans. The Calvin cycle converts carbon dioxide into sugar, as triose phosphate (TP), which

2960-468: The Campylobacterota . This feature allows primary production in the ocean's aphotic environments , or "dark primary production." Without it, there would be no primary production in aphotic environments, which would lead to habitats without life. The cycle involves the biosynthesis of acetyl-CoA from two molecules of CO 2 . The key steps of the reverse Krebs cycle are: This pathway

3034-722: The biosphere . Carbon is considered essential for life as a base element for building organic compounds. The element of carbon forms the bases biogeochemical cycles (or nutrient cycles ) and drives communities of living organisms. Understanding biological carbon fixation is essential for comprehending ecosystem dynamics , climate regulation, and the sustainability of life on Earth. Organisms that grow by fixing carbon, such as most plants and algae , are called autotrophs . These include photoautotrophs (which use sunlight) and lithoautotrophs (which use inorganic oxidation ). Heterotrophs , such as animals and fungi , are not capable of carbon fixation but are able to grow by consuming

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3108-517: The cyanobacteria . It also fixes carbon in the anoxygenic photosynthesis in one type of Pseudomonadota called purple bacteria , and in some non-phototrophic Pseudomonadota. Of the other autotrophic pathways, two are known only in bacteria (the reductive citric acid cycle and the 3-hydroxypropionate cycle ), two only in archaea (two variants of the 3-hydroxypropionate cycle), and one in both bacteria and archaea (the reductive acetyl CoA pathway ). Sulfur- and hydrogen-oxidizing bacteria often use

3182-434: The accumulation of atmospheric CO2 and mitigate climate change but also enhances soil fertility, water retention, and nutrient cycling , thereby supporting plant growth and ecosystem productivity. Consequently, understanding the role of soil microbes in biological carbon fixation is essential for managing soil health , mitigating climate change, and promoting sustainable land management practices. Biological carbon fixation

3256-404: The activity of microorganisms, such as bacteria and fungi. These soil microbes play a crucial role in the global carbon cycle by sequestering carbon from decomposed organic matter and recycling it back into the soil, thereby contributing to soil fertility and ecosystem productivity.   In soil environments, organic matter derived from dead plant and animal material undergoes decomposition ,

3330-439: The air and water: Carbon dioxide is colorless. At low concentrations, the gas is odorless; however, at sufficiently high concentrations, it has a sharp, acidic odor. At standard temperature and pressure , the density of carbon dioxide is around 1.98 kg/m , about 1.53 times that of air . Carbon dioxide has no liquid state at pressures below 0.51795(10) MPa (5.11177(99) atm ). At a pressure of 1 atm (0.101325 MPa),

3404-444: The air, carbon dioxide is transparent to visible light but absorbs infrared radiation , acting as a greenhouse gas . Carbon dioxide is soluble in water and is found in groundwater , lakes , ice caps , and seawater . It is a trace gas in Earth's atmosphere at 421  parts per million (ppm) , or about 0.042% (as of May 2022) having risen from pre-industrial levels of 280 ppm or about 0.028%. Burning fossil fuels

3478-430: The atmosphere. Less than 1% of CO2 produced annually is put to commercial use, mostly in the fertilizer industry and in the oil and gas industry for enhanced oil recovery . Other commercial applications include food and beverage production, metal fabrication, cooling, fire suppression and stimulating plant growth in greenhouses. Carbon dioxide cannot be liquefied at atmospheric pressure. Low-temperature carbon dioxide

3552-669: The carbon fixed by autotrophs or other heterotrophs. Six natural or autotrophic carbon fixation pathways are currently known. They are the: i) Calvin-Benson-Bassham (Calvin Cycle), ii) Reverse Krebs (rTCA) cycle, iii) the reductive acetyl-CoA (Wood-Ljungdahl pathway), iv) 3-hydroxy propionate [3-HP] bicycle , v) 3-hydroypropionate/4- hydroxybutyrate (3-HP/4-HB) cycle, and vi) the dicarboxylate/ 4-hydroxybutyrate (DC/4-HB) cycle. "Fixed carbon," "reduced carbon," and "organic carbon" may all be used interchangeably to refer to various organic compounds. The primary form of fixed inorganic carbon

3626-444: The carboxylation of propionyl-CoA to methylamalonyl-CoA. From this point a series of reactions lead to the formation of glyoxylate which will thus become part of the second cycle. In the second cycle, glyoxylate is approximately one equivalent of propionyl-CoA forming methylamalonyl-CoA. This, in turn, is then converted through a series of reactions into citramalyl-CoA. The citramalyl-CoA is split into pyruvate and Acetyl-CoA thanks to

3700-869: The condition. There are few studies of the health effects of long-term continuous CO 2 exposure on humans and animals at levels below 1%. Occupational CO 2 exposure limits have been set in the United States at 0.5% (5000 ppm) for an eight-hour period. At this CO 2 concentration, International Space Station crew experienced headaches, lethargy, mental slowness, emotional irritation, and sleep disruption. Studies in animals at 0.5% CO 2 have demonstrated kidney calcification and bone loss after eight weeks of exposure. A study of humans exposed in 2.5 hour sessions demonstrated significant negative effects on cognitive abilities at concentrations as low as 0.1% (1000   ppm) CO 2 likely due to CO 2 induced increases in cerebral blood flow. Another study observed

3774-517: The degenerate pair of bending modes at 667 cm (wavelength 15.0 μm). The symmetric stretching mode does not create an electric dipole so is not observed in IR spectroscopy, but it is detected in Raman spectroscopy at 1388 cm (wavelength 7.20 μm), with a Fermi resonance doublet at 1285 cm . In the gas phase, carbon dioxide molecules undergo significant vibrational motions and do not keep

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3848-566: The dispersing effects of wind, it can collect in sheltered/pocketed locations below average ground level, causing animals located therein to be suffocated. Carrion feeders attracted to the carcasses are then also killed. Children have been killed in the same way near the city of Goma by CO 2 emissions from the nearby volcano Mount Nyiragongo . The Swahili term for this phenomenon is mazuku . Adaptation to increased concentrations of CO 2 occurs in humans, including modified breathing and kidney bicarbonate production, in order to balance

3922-541: The effects of blood acidification ( acidosis ). Several studies suggested that 2.0 percent inspired concentrations could be used for closed air spaces (e.g. a submarine ) since the adaptation is physiological and reversible, as deterioration in performance or in normal physical activity does not happen at this level of exposure for five days. Yet, other studies show a decrease in cognitive function even at much lower levels. Also, with ongoing respiratory acidosis , adaptation or compensatory mechanisms will be unable to reverse

3996-551: The electrical conductivity of fully deionized water without CO 2 saturation is comparably low in relation to these data. CO 2 is a potent electrophile having an electrophilic reactivity that is comparable to benzaldehyde or strongly electrophilic α,β-unsaturated carbonyl compounds . However, unlike electrophiles of similar reactivity, the reactions of nucleophiles with CO 2 are thermodynamically less favored and are often found to be highly reversible. The reversible reaction of carbon dioxide with amines to make carbamates

4070-422: The enzyme MMC lyase. At this point the pyruvate is released, while the Acetyl-CoA is reused and carboxylated again at Malonyl-CoA thus reconstituting the cycle. A total of 19 reactions are involved in 3-hydroxypropionate bicycle and 13 multifunctional enzymes are used. The multifunctionality of these enzymes is an important feature of this pathway which thus allows the fixation of three bicarbonate molecules. It

4144-469: The gas deposits directly to a solid at temperatures below 194.6855(30) K (−78.4645(30) °C) and the solid sublimes directly to a gas above this temperature. In its solid state, carbon dioxide is commonly called dry ice . Liquid carbon dioxide forms only at pressures above 0.51795(10) MPa (5.11177(99) atm); the triple point of carbon dioxide is 216.592(3) K (−56.558(3) °C) at 0.51795(10) MPa (5.11177(99) atm) (see phase diagram). The critical point

4218-601: The harvestable yield of crops, with wheat, rice and soybean all showing increases in yield of 12–14% under elevated CO 2 in FACE experiments. Increased atmospheric CO 2 concentrations result in fewer stomata developing on plants which leads to reduced water usage and increased water-use efficiency . Studies using FACE have shown that CO 2 enrichment leads to decreased concentrations of micronutrients in crop plants. This may have knock-on effects on other parts of ecosystems as herbivores will need to eat more food to gain

4292-522: The lighter carbon stable isotope carbon-12 over the heavier carbon-13 . This is known as carbon isotope discrimination and results in carbon-12 to carbon-13 ratios in the plant that are higher than in the free air. Measurement of this ratio is important in the evaluation of water use efficiency in plants, and also in assessing the possible or likely sources of carbon in global carbon cycle studies. In addition to photosynthetic and chemosynthetic processes, biological carbon fixation occurs in soil through

4366-424: The main choice for chemolithoautotrophs limited in energy and living in anaerobic conditions. The 3-Hydroxypropionate bicycle , also known as 3-HP/malyl-CoA cycle, discovered only in 1989, is utilized by green non-sulfur phototrophs of Chloroflexaceae family, including the maximum exponent of this family Chloroflexus auranticus by which this way was discovered and demonstrated. The 3-Hydroxipropionate bicycle

4440-444: The majority of the carbon dioxide is not converted into carbonic acid, but remains as CO 2 molecules, not affecting the pH. The relative concentrations of CO 2 , H 2 CO 3 , and the deprotonated forms HCO − 3 ( bicarbonate ) and CO 2− 3 ( carbonate ) depend on the pH . As shown in a Bjerrum plot , in neutral or slightly alkaline water (pH > 6.5), the bicarbonate form predominates (>50%) becoming

4514-478: The majority were supplying power to the Danish grid. On 3 August, E.ON reported that the wind farm was ready and went into operation, three months ahead of schedule. Rødsand 2 was inaugurated on 12 October. In November 2013, local power company SEAS-NVE bought 80% of Rødsand 2 for a price of DKK 2.8 billion and thus valuating the wind farm at DKK 3.5 billion. Carbon dioxide Carbon dioxide

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4588-443: The most prevalent (>95%) at the pH of seawater. In very alkaline water (pH > 10.4), the predominant (>50%) form is carbonate. The oceans, being mildly alkaline with typical pH = 8.2–8.5, contain about 120 mg of bicarbonate per liter. Being diprotic , carbonic acid has two acid dissociation constants , the first one for the dissociation into the bicarbonate (also called hydrogen carbonate) ion ( HCO − 3 ): This

4662-608: The origin of life. Six autotrophic carbon fixation pathways are known: the Calvin Cycle, the Reverse Krebs Cycle, the reductive acetyl-CoA, the 3-HP bicycle, the 3-HP/4-HB cycle, and the DC/4-HB cycles. The organisms the Calvin cycle is found in are plants, algae, cyanobacteria , aerobic proteobacteria, and purple bacteria. The Calvin cycle fixes carbon in the chloroplasts of plants and algae, and in

4736-594: The outdoor concentration is 400 ppm, indoor concentrations may reach 2,500 ppm with ventilation rates that meet this industry consensus standard. Concentrations in poorly ventilated spaces can be found even higher than this (range of 3,000 or 4,000 ppm). Carbon fixation Biological carbon fixation , or сarbon assimilation , is the process by which living organisms convert inorganic carbon (particularly carbon dioxide ) to organic compounds . These organic compounds are then used to store energy and as structures for other biomolecules . Carbon

4810-495: The presence of carbon dioxide in water also affects its electrical properties. When carbon dioxide dissolves in desalinated water, the electrical conductivity increases significantly from below 1 μS/cm to nearly 30 μS/cm. When heated, the water begins to gradually lose the conductivity induced by the presence of C O 2 {\displaystyle \mathrm {CO_{2}} } , especially noticeable as temperatures exceed 30 °C. The temperature dependence of

4884-499: The presence of sufficient oxygen, manifesting as dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour. Concentrations of more than 10% may cause convulsions, coma, and death. CO 2 levels of more than 30% act rapidly leading to loss of consciousness in seconds. Because it is heavier than air, in locations where the gas seeps from the ground (due to sub-surface volcanic or geothermal activity) in relatively high concentrations, without

4958-496: The products of their photosynthesis as internal food sources and as raw material for the biosynthesis of more complex organic molecules, such as polysaccharides , nucleic acids , and proteins. These are used for their own growth, and also as the basis of the food chains and webs that feed other organisms, including animals such as ourselves. Some important phototrophs, the coccolithophores synthesise hard calcium carbonate scales. A globally significant species of coccolithophore

5032-409: The reduction of CO 2 to a methyl residue bound to a cofactor. The intermediates are formate for bacteria and formyl-methanofuran for archaea, and also the carriers, tetrahydrofolate and tetrahydropterins respectively in bacteria and archaea, are different, such as the enzymes forming the cofactor-bound methyl group. Otherwise, the carbonyl branch is homologous between the two domains and consists of

5106-448: The reduction of another molecule of CO 2 to a carbonyl residue bound to an enzyme, catalyzed by the CO dehydrogenase/acetyl-CoA synthase. This key enzyme is also the catalyst for the formation of acetyl-CoA starting from the products of the previous reactions, the methyl and the carbonyl residues. This carbon fixation pathway requires only one molecule of ATP for the production of one molecule of pyruvate, which makes this process one of

5180-420: The same amount of protein. The concentration of secondary metabolites such as phenylpropanoids and flavonoids can also be altered in plants exposed to high concentrations of CO 2 . Plants also emit CO 2 during respiration, and so the majority of plants and algae, which use C3 photosynthesis , are only net absorbers during the day. Though a growing forest will absorb many tons of CO 2 each year,

5254-411: The same frequency and same energy, because of the symmetry of the molecule. When a molecule touches a surface or touches another molecule, the two bending modes can differ in frequency because the interaction is different for the two modes. Some of the vibrational modes are observed in the infrared (IR) spectrum : the antisymmetric stretching mode at wavenumber 2349 cm (wavelength 4.25 μm) and

5328-451: The synthesis of extracellular polymers , enzymes, and other biochemical compounds . These substances help bind soil particles together, forming aggregates that protect organic carbon from microbial decomposition and physical erosion . Over time, these aggregates accumulate in the soil, resulting in the formation of soil organic matter, which can persist for centuries to millennia. The sequestration of carbon in soil not only helps mitigate

5402-535: The upper ocean and thereby promotes the absorption of CO 2 from the atmosphere. Carbon dioxide content in fresh air (averaged between sea-level and 10 kPa level, i.e., about 30 km (19 mi) altitude) varies between 0.036% (360 ppm) and 0.041% (412 ppm), depending on the location. In humans, exposure to CO 2 at concentrations greater than 5% causes the development of hypercapnia and respiratory acidosis . Concentrations of 7% to 10% (70,000 to 100,000 ppm) may cause suffocation, even in

5476-546: The water, or to the lungs from where it is exhaled. During active photosynthesis, plants can absorb more carbon dioxide from the atmosphere than they release in respiration. Carbon fixation is a biochemical process by which atmospheric carbon dioxide is incorporated by plants, algae and cyanobacteria into energy-rich organic molecules such as glucose , thus creating their own food by photosynthesis. Photosynthesis uses carbon dioxide and water to produce sugars from which other organic compounds can be constructed, and oxygen

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