Phosphates

Abstract

Although phosphorus is the eleventh most abundant element in the Earth’s crust, where it forms approximately 1120 mg kg1, it is geochemically classed as a trace element [1, 2]. In the lithosphere, it occurs as phosphates, and these may be leached by weathering processes into the hydrosphere. Phosphorus may then be precipitated as insoluble metal phosphates, which are incorporated into sediments and cycled on a geological timescale (millions of years), or it can participate in the rapid terrestrial and aquatic biological phosphorus cycles.