Lead from gasoline gets into seawater when lead in automobile exhaust attaches to fine particles in the atmosphere. About 10 percent of the particles, which include lead from the smokestacks of industrial countries, catch a ride on the wind to remote regions of the ocean and polar ice cores. While lead from industrialized countries moves all around the oceans, the Atlantic in particular receives lead from the United States on westerlies and from Europe on the trade winds. After it falls into surface ocean water, lead is converted into soluble form. It then falls to deeper water on sinking biological particles, such as fecal pellets.
Lead remains in surface waters for about two years, and up to a few hundred years in deep water.
While the elimination of lead from gasoline helped reduce lead levels in food, and lead paint and lead piping regulations also have reduced exposure, high-temperature industrial activities such as smelting, coal combustion and cement production may be the most recent culprits behind the residual lead in ocean surface water, Boyle said.