Strontium [Sr, 38]

Strontium (Sr) is a metal of group 2 in the periodic table of elements and has a silver appearance, before rapid oxidation, after which it turns into a yellowish color. It is relatively common in the Earth’s crust, in contents within the range of 260–730 mg/kg. Worldwide background mean levels of Sr in soils are estimated to be 130–240 mg/kg. In some heavy loamy soils, and in soils from industrial regions, Sr content may be above 1000 mg/kg. The main sources of Sr pollution are from coal combustions and sulfur mining and processing. Phosphorites may contain elevated amounts of Sr, up to about 2000 mg/kg. Most of the aquatic organisms may accumulate Sr. This process is an inverse correlation to calcium levels in water. Mussels from the Baltic Sea may accumulate Sr up to 100 mg/kg. There are several isotopic species of Sr in the geological formations. Biogeochemical behavior of ⁹⁰ Sr is similar to stable Sr.