THE IMPACT OF ATMOSPHERIC AEROSOLS ON TRACE-METAL CHEMISTRY IN OPEN OCEAN SURFACE SEAWATER .3. LEAD

Atmospheric aerosols collected at Enewetak Atoll in the tropical North Pacific were exposed to seawater in laboratory experiments. The net atmospheric flux of soluble lead to the ocean is between 16 and 32 pmol cm-2yr-1 at Enewetak. The stable lead isotopic composition of soluble aerosol lead indicates that it is of anthropogenic origin. Anthropogenic aerosol lead from Central and North America appears to be less soluble and/or to dissolve less rapidly than that from Asia. Dissolved organic matter and possibly lower pH appear to increase the nonaluminosilicate aerosol lead solubility and/or dissolution rate. The isotopic composition of lead in air, seawater and dry deposition suggest that after deposition in the ocean, nonaluminosilicate particulate lead can be reinjected into the atmosphere during sea salt aerosol production. -from Authors