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Most water in Earth's atmosphere and crust comes from saline seawater, while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Earth is saline or salt water, with an average salinity of 35‰ (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land.
While the majority of Earth's surface is covered by oceans, those oceans make up just a small fraction of the mass of the planet. The mass of Earth's oceans is estimated to be 1.37 × 10 21 kg, which is 0.023% of the total mass of Earth, 6.0 × 10 24 kg.
An essential amino acid is an amino acid that is required by an organism but cannot be synthesized de novo by it, and therefore must be supplied in its diet. Out of the twenty standard protein-producing amino acids, nine cannot be endogenously synthesized by humans: phenylalanine , valine , threonine , tryptophan , methionine , leucine ...
Hugh Hammond Bennett. Hugh Hammond Bennett (April 15, 1881 – July 7, 1960) was a pioneer in the field of soil conservation in the United States of America.He was the head of the Soil Conservation Service, a federal agency now referred to as the Natural Resources Conservation Service.
This is an accepted version of this page This is the latest accepted revision, reviewed on 19 February 2025. Water located beneath the ground surface An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it. Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in ...
In plants and animals, mineral absorption, also called mineral uptake is the way in which minerals enter the cellular material, typically following the same pathway as water.
Carbonic anhydrase, an enzyme that requires zinc (gray sphere near the center of this image), is essential for exhalation of carbon dioxide.. In the context of nutrition, a mineral is a chemical element.
The USGS also operates the National Wildlife Health Center, whose mission is "to serve the nation and its natural resources by providing sound science and technical support, and to disseminate information to promote science-based decisions affecting wildlife and ecosystem health. The NWHC provides information, technical assistance, research ...