Award: OCE-1234213

As a component of the international GEOTRACES program, this study focused on the distribution of lead and its isotopes in the South Pacific. These data are needed for a global study of the sources of natural and industrial lead in the world's oceans. They are important because previous studies in the late 1900s showed surprisingly high levels of industrial lead contamination in both the North Pacific and North Atlantic; but the South Pacific appeared to be much less contaminated, based on a very few measurements. Since then lead levels in the North Pacific and North Atlantic have declined with the elimination of leaded gasoline and other environmental controls on lead emissions. In contrast, this study indicates that lead concentrations in the South Pacific have remained relatively constant over the past three decades, indicating that most of the lead in those waters is derived from natural sources. Since lead and its isotopes are tracers of other industrial pollutants, these results further indicate those southern waters are also relatively pristine compared to northern oceanic waters. These results substantiate other studies that indicate atmospheric pollutants tend to remain within the hemisphere they are emitted. As a result, the North Pacific and North Atlantic are relatively more contaminated by industrial emissions in the northern hemisphere, which are much greater than those emissions in the southern hemisphere. The results also show the global contamination of persistent pollutants, including lead, can be reduced with rigorous environmental controls. Last Modified: 01/29/2018 Submitted by: Arthur Flegal