9633125 SANTSCHI The various naturally-occurring radioactive isotopes of thorium (Th) have come to prominence in chemical oceanography because of their utility in determining the rates of flux of large particulate and colloidal subparticles. The tendency of Th to preferentially come out of good tracer for particle dynamics (production, destruction, sinking, mixing). However, the computations involved are model-based, and the models currently used are rather simplistic. In this research, the PI and his coworkers at Texas A&M University will conduct laboratory experiments to determine the sorption-description kinetic properties of Th in seawater with particles, organic molecules, and colloids aggregate into larger and larger aggregates, a process responsible for the formation of new particles in marine and other natural waters. The results will finally be folded into a more realistic model of Th behavior that should help marine chemists and geochemists use the Th tracer more confidently and with a better understanding of its limitations as well as its utility.
