ABSTRACT

Rubidium (Rb) is a silvery-white soft metal of group 1 in the periodic table of elements, with properties similar to alkali metals. Rubidium contents in soils are largely inherited from the parent materials, and therefore, its highest contents, 100–120 mg/kg, are in soils derived from granites and gneisses. The lowest Rubidium contents are in sandy and organic soils. The significant, positive correlation between Rubidium contents and clay fraction in soils clearly indicates its sorption by fine fractions. Rubidium is easily taken up by plants, similarly as other monovalent cations. The contents of available K control the Rubidium uptake. Increased bioavailability of Rubidium in acidic soils is a secondary effect of leaching losses of K. Rubidium is toxic and is removed relatively quickly in perspiration and urine. Rubidium is very active in air and forms easily monoxide and hydroxide compounds. In the heart, Rb is lower in conductive tissue than in adjacent muscle tissue.