Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms that may deplete the water of oxygen. Although eutrophication is a natural process, manmade or cultural eutrophication is far more common and is a rapid process caused by a variety of polluting inputs including poorly treated sewage, industrial wastewater, and fertilizer runoff. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in water and causing substantial environmental degradation.
Eutrophication can cause harmful algal blooms like this one in a river near Chengdu, China.
An example in Tennessee of how soil from fertilized fields can turn into runoff after a storm, creating a flux of nutrients that flow into local bodies of water such as lakes and creeks.
The eutrophication of Mono Lake, which is a cyanobacteria-rich soda lake
Eutrophication is apparent as increased turbidity in the northern part of the Caspian Sea, imaged from orbit.
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.
Oxygen-filled discharge tube glowing purple.
Joseph Priestley is usually given priority in the discovery.
Antoine Lavoisier discredited the phlogiston theory.
Robert H. Goddard and a liquid oxygen-gasoline rocket
