Zirconium [Zr, 40]

Zirconium (Zr), a lustrous, grayish-white metal of group 4 in the periodic table of elements, is soft, ductile, and malleable, and exhibits both oxyphilic and lithophilic tendencies. Zirconium contents of soils are mainly inherited from parent rocks, and therefore, its distribution in soil profiles is often used in studies of soil genetic. Soils contain Zr within the range of 90–850 mg/kg, and the highest concentration is in heavy loamy soils. Due to low solubility of Zr compounds and minerals, its concentration in surface waters is relatively low. Zirconium contents of food plants vary from 0.005 to 2.5 mg/kg, being lowest in cereal grains and highest in peanuts and beans. Zirconium has no known biological role or toxicity. It is biocompatible and is used for surgical implants and prosthetic devices. Zirconium is able to cross the blood-brain barrier and the placental barrier.