ABSTRACT

²¹⁰Pb and ²¹⁰Po in sea water of the Pacific were determined and applied to make clear the behavior of lead in the surface water of the ocean. The concentration of ²¹⁰Pb in the surface water was much smaller than the expected value, if it were soluble in sea water. Its geographical distribution showed a latitudinal variation which presented the higher values in both mid-latitudes of the Pacific and the lower values in the tropical Pacific and the southern South Pacific. These facts suggest that lead is settling with the velocity of (1-5) × 10^-4 cm/sec in the surface layer. However, it is very unlikely that the lead exists as pure solid phase of lead oxide. The lead probably forms an eutectic solid phase with other host metals such as manganese oxide. The ratios of ²¹⁰Po to ²¹⁰Pb in surface water were larger than those in meteoric precipitation, but most of them were smaller than unity.