BURSTING BUBBLES AND THEIR EFFECT ON THE SEA-TO-AIR TRANSPORT OF FE, CU AND ZN

The effects of the bubble breaking process on the atmospheric geochemical cycles of the elements Fe, Cu and Zn were investigated, in situ, in the estuarine waters of Narragansett Bay, Rhode Island. Enrichment, as defined by the metal-to-sodium ratios in the aerosols produced compared to their ratio in bulk water, occurred for the three metals investigated. The extent and potential geochemical importance of the process were different for each element. Iron enrichment was quite low (enrichment factor (EF) <100) and constant, and scavenging of iron from the water column and subsequent enrichment on the aerosols produced did not appear to occur. Copper enrichment on the aerosols was ∼ 200 and appeared to be influenced by both microlayer and scavenging effects. In addition, copper enrichment appears to be correlated to biological processes. Zinc enrichment was approximately the same as Cu; however, a strong scavening effect appeared to occur, suggesting scavenging of Zn by rising bubbles. Scavenging effects suggest that open-ocean enrichments for Cu may be slightly higher than observed here and a great deal higher for Zn. Geochemical implications of the data, together with other existing data, indicate that the sea is an insignificant source of Fe to the atmosphere. The sea may be a significant source (contributing on the order of 10% or more) of the total annual quantity of Cu and Zn to the atmosphere. © 1979.