Fractionation of carbon isotopes in oxygenic photosynthesis characterization of food chains. Oxygenic photosynthesis is a metabolic pathway facilitated by autotrophs, including plants, algae, and cyanobacteria. This pathway converts inorganic carbon dioxide from the atmosphere or aquatic environment into carbohydrates, using water and energy from light, then releases molecular oxygen as a product. Organic carbon contains less of the stable isotope Carbon-13, or C, relative to the initial inorganic carbon from the atmosphere or water because photosynthetic carbon fixation involves several fractionating reactions with kinetic isotope effects. These reactions undergo a kinetic isotope effect because they are limited by overcoming an activation energy barrier. The lighter isotope has
Carbon dioxide Most of the remaining 50–55% is methane. Carbon dioxide is used by the food industry, the oil industry, and the chemical industry. The compound has varied commercial uses but one of its greatest use as a chemical is in the production of carbonated beverages; it provides the sparkle in carbonated beverages such as soda water, beer and sparkling wine. In the chemical industry, carbon dioxide is mainly consumed as an ingredient in the production of urea, with a smaller fraction being used to produce methanol and a range of other products, such as metal carbonates and bicarbonates. Some carboxylic acid