COMPTON SUPPRESSION GAMMA-SPECTROSCOPY IN THE ANALYSIS OF RADIUM AND LEAD ISOTOPES IN OCEAN SEDIMENTS

Compton suppression gamma-spectroscopy provides an efficient method fo r measuring the concentration of Ra-226, Ra-228, and Pb-210 in ocean s ediments. The background reduction realized from the suppressed mode o f operation provides an ''active shield'' to allow for the low-level c ounting required for these measurements. We have used the method to st udy the possible accumulation of radium from produced waters in sedime nts from Gulf of Mexico sites of varied distances from drill platforms . In addition, Pb-210 levels were determined to evaluate the use of ou r spectrometer for this purpose. Baseline undisturbed concentrations h ave been obtained from the study of subsurface core material which pre dates drilling activities. Correlations of radium isotope concentratio ns with iron and barium provide information concerning the possible re lationships between radium levels and drilling activity (excess barium ) and natural variations in sediment texture (iron).