Search results
Results From The WOW.Com Content Network
In food science, water activity (a w) of a food is the ratio of its vapor pressure to the vapor pressure of water at the same temperature, both taken at equilibrium. [1] Pure water has a water activity of one. Put another way, a w is the equilibrium relative humidity (ERH) expressed as a fraction instead of as a percentage.
Since liquid water flows, ocean waters cycle and flow in currents around the world. Since water easily changes phase, it can be carried into the atmosphere as water vapour or frozen as an iceberg. It can then precipitate or melt to become liquid water again. All marine life is immersed in water, the matrix and womb of life itself. [7]
The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion; this oxygen-evolving complex binds two water molecules and contains the four oxidizing equivalents that are used to drive the water-oxidizing reaction (Kok's S-state diagrams).
These two processes have a significant effect on the atmospheric carbon dioxide concentration, making their correct functioning essential to sustaining life. Without carbon dioxide, plants would not be able to carry out photosynthesis, in turn not producing oxygen, affecting all forms of life on earth.
Through photosynthesis, plants use CO 2 from the atmosphere, water from the ground, and energy from the sun to create sugars used for growth and fuel. [22] While using these sugars as fuel releases carbon back into the atmosphere (photorespiration), growth stores carbon in the physical structures of the plant (i.e. leaves, wood, or non-woody stems). [23]
The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports carbon and then exports it back to the atmosphere and ocean floor The biological pump (or ocean carbon biological pump or marine biological carbon pump ) is the ocean's biologically driven sequestration of carbon from the atmosphere and land ...
When oxygen is present, aerobic respiration occurs, producing carbon dioxide. If oxygen is not present, e.g. as is the case in marshes or in animals' digestive tracts, anaerobic respiration can occur, which produces methane. About half of the gross primary production is respired by plants directly back into the atmosphere.
Ocean iron fertilization is an example of a geoengineering technique that involves intentional introduction of iron-rich deposits into oceans, and is aimed to enhance biological productivity of organisms in ocean waters in order to increase carbon dioxide (CO 2) uptake from the atmosphere, possibly resulting in mitigating its global warming effects.