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
Ocean storage of carbon dioxide dioxide is 10,000 years for a 50 m deep lake. This number is decreased by more than 25 times with currents from ocean bottom storms. Sites would be chosen based on ocean floor depth, seismic and volcanic activity, and the presence of CaCO deposits that could increase the rate of carbon mineralization. Some sites proposed for storage at depths greater than 6 km include the Indonesian Sunda trench, the Japanese Ryukyu trench, and the Puerto Rico trench. Researchers are studying how ecosystems are affected before and after injection of liquid carbon dioxide through "process studies, surveys of biogeochemical tracers, and