EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > NUTRIENTS > PHOSPHOROUS
A chemical element with symbol P and atomic number 15. As an element, phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. With a concentration of 0.099%, phosphorus is the most abundant pnictogen in the Earth's crust. Other than a few exceptions, minerals containing phosphorus are in the maximally oxidized state as inorganic phosphate rocks.