Author(s): E Keith Bigg, Caroline Leck
Air bubbles bursting on artificial seawater in laboratory experiments have been foundto inject numerous particles <200 nm diameter into the atmosphere, some experimentsshowing copious production of particles as small as 10 nm. Some observations of thereal marine aerosol support the presence of a large proportion of sea salt <200 nmdiameter, while others suggest that it is absent, or nearly so. It is argued here that theobservations showing its presence may be misinterpretations. If this is so, modification ofcurrently accepted theories of particle injection into the atmosphere by bursting bubbleswould be required. Highly surface active exopolymers produced by bacteria and algae, themicrogels formed by them, and large concentrations of submicrometer particulates areknown to be present in the ocean. Their possible influence on bubble formation, bubblebursting and particle injection into the atmosphere are discussed. Electron microscopy ofindividual particles at a number of sites supports the proposal that the exopolymers areinvolved in these processes. Ultraviolet light and acidification cause structural andchemical changes to exopolymers and their gels exposed to the atmosphere so that marineaerosol will have properties that change with atmospheric residence time.