The proposal seeks to carry out basic studies to determine the siting of U, Be, Sr and other cations in recent and old corals. A specific aim of the work is to determine whether these elements exist partly or primarily as adsorbed onto organic matter, or are exclusively sited within the lattice. This knowledge is an essential prerequisite for using corals as paleorecorders of wide- ranging geophysical and geochemical information, e.g., oceanic 234U/238U and 10Be/9Be ratios, seawater metal concentrations and atmospheric 14C/12C ratios. Our studies will attempt to assess whether coral compositions can be used for examining variability in the geophysical parameter(s) of interest, and should help determine the reliability of coral 14C/12C ratios, and also suggest suitable methods to extract such information in a reliable manner, free of effects due to diagenesis. For example, if our studies show that certain cations in corals are primarily adsorbed on organic matter, the concentrations of those cations would be subject to exchange with the environment. To use such elements for paleoenvironment studies, it would be necessary to extract cations from the aragonite lattice only. We also propose to examine the suitability of corals for determining surface oceanic 10Be/9Be ratios in the past. 10Be is produced by cosmic ray nuclear interactions in the atmosphere. The 10Be half-life of 1.5 my promises to allow dating corals of several millions of years' age from analyses of samples of <50 gm weight. The proposal is clearly exploratory in character, aiming at enhancing the potential of corals as recorders of global paleoclimatic and paleo-oceanographic parameters.
