Princeton's WordNet (2.25 / 4 votes) Rate this definition: unit of measurement, unit (noun). any division of quantity accepted as a standard of measurement or exchange. the dollar is the United States unit of currency; a unit of wheat is a bushel; change per unit volume. unit (noun).nit. 1. Any military element whose structure is prescribed by competent authority, such as a table of organization and equipment; specifically, part of an organization. 2. An organization title of a subdivision of a group in a task force.
Oxygen can be found on most of the earth and is needed by many living beings. Our atmosphere is composed of about 20% oxygen. The element oxygen (O2) is found in water (H2O),â¦ which is made up of 2 parts Hydrogen and 1 part oxygen. It is also found in rust and metal ores, as well as in many different minerals. Another place is anywhere there are green plants or trees.
Oxygen makes up about 21% of the air we breathe and half of this oxygen is produced by phytoplankton in the ocean. All aerobic life requires oxygen to produce energy. In water, oxygen is found in a dissolved form and is much more limiting. For this reason, we measure dissolved oxygen in water not in % but in units of umol/kg. The highest concentrations of dissolved oxygen in the ocean are found within the surface mixed layer at concentrations of > 200 umol/kg.