10 Be: recent applications in Earth sciences

Abstract
10Be, a cosmogenic isotope produced by cosmic rays interacting with the Earth ’s atmosphere and surface, has chemical and physical properties that make it useful as a tracer for some terrestrial processes and a geological clock for a few substances. The rarity of the stable isotope, 9Be, allows 10Be to be detected in natural materials at extremely low levels with backgrounds for rocks, sediments etc. below 105 atom g-1 now attainable, a value to be com pared with an average annual global deposition rate of 1.3 x 106 atom cm-2. The affinity of Be for the components of soil and sediment is sufficiently high that its contact with them effectively immobilizes it, thereby allowing 10Be to function as a tracer of sediment transport. The half-life of 1.5 Ma is convenient for some geological studies. Application has been found in cosmic-ray history, formation of manganese nodules, pelagic sedimentation, island-arc volcanism, soil evolution, soil erosion and rock weathering.