Polonium-210 and lead-210 in the marine environment

A method is outlined for the determination of lead-210 and polonium-210 in sea water by solvent extraction, followed by electrodeposition and alpha counting. Data are given for the lead-210 and polonium-210 content of twenty nine samples collected at a depth of 20 m in the sea around the Cape of Good Hope during March 1969. The mean activities of lead-210 and polonium-210 in these sea water samples were 38 × 10-15 c/1 and 20 × 10-15 c/1 respectively. Real variations in the concentrations of these nuclides were found to exist, and these could in part be ascribed to different water masses and current systems. The lead-210 and polonium-210 contents of eleven Zooplankton and three phytoplankton samples collected during the same period were also determined. Mean values for lead-210 and polonium-210 in Zooplankton were 33 pc/kg wet weight and 399 pc/kg wet weight respectively. A correlation between these nuclides in Zooplankton was found to exist, the lead-210 activity being on the average one twelfth of the polonium-210 activity. An attempt has been made to evaluate the biogeochemical balance of lead-210 and polonium-210 in the marine environment. Using the data presented, and making certain stated assumptions, the removal times of these nuclides from the upper mixed layer have been calculated. These times were found to be about 5 yr for lead-210 and 0.6 yr for polonium-210. © 1970.