DETERMINATION OF RUBIDIUM IN SEAWATER1

Rubidium concentrations in seawater from various locations and depths to 3,900 m have been determined using two independent techniques—direct flame photometry and mass spectrometry. Results of these two techniques agree within estimated errors and indicate that the rubidium content in the oceans is uniform within ±8% with values varying about 120 µ g/liter. Sediment from the sea floor below a depth profile, analyzed for rubidium and potassium, gave a rubidium concentration factor of 150 and a potassium to rubidium ratio of 1,270.