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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]
Hydrogen and oxygen are found in water and organic molecules, both of which are essential to life. Carbon is found in all organic molecules, whereas nitrogen is an important component of nucleic acids and proteins. Phosphorus is used to make nucleic acids and the phospholipids that comprise biological membranes. Sulfur is critical to the three ...
The biological pump is not so much the result of a single process, but rather the sum of a number of processes each of which can influence biological pumping. Overall, the pump transfers about 10.2 gigatonnes of carbon every year into the ocean's interior and a total of 1300 gigatonnes carbon over an average 127 years. [3]
The upper value, 5.0, is unusual, even for large fish, [7] though it occurs in apex predators of marine mammals, such as polar bears and killer whales. [8] As a point of contrast, humans have a mean trophic level of about 2.21, about the same as a pig or an anchovy. [9] [10]
The aquatic microbial loop is a marine trophic pathway which incorporates dissolved organic carbon into the food chain.. The microbial loop describes a trophic pathway where, in aquatic systems, dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton.
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] Iron- and sulfur-based Anoxygenic photosynthesis life forms that lived from 3.80 to 3.85 billion years ago on Earth produced an abundance of black ...
The Earth's water cycle. About 97.5% of the water on Earth is saline; the remaining 2.5% is fresh water. Most fresh water – about 69% – is present as ice in ice caps and glaciers. [20] The average salinity of Earth's oceans is about 35 grams (1.2 oz) of salt per kilogram of seawater (3.5% salt). [21]
[9] [10] [11] The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago, [12] [13] during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. Microbial mat fossils have been found in 3.48 billion-year-old sandstone in Western Australia. [14] [15]