Circumstantial evidence in support of org-I as a component of the marine aerosol arising from a study of marine foams

A study of foams formed on the marine Lake Mir, Croatia, and elsewhere on the same coast demonstrates, for the first time, that they are fractionated (enrichened) in org-I by up to 630 times relative to the water from which they form. The results are consistent with an I/C mole ratio for in-situ organic matter. Foams created artificially in the laboratory from natural samples of water from Lake Mir were similarly fractionated, although to a lesser degree. These differences were effectively removed when enrichments were expressed as molar ratios, e.g., Ptot/Itot, rather than straightforward concentrations. This similarity in the behaviour to enrichment for organic forms of I, N and P suggests that the time over which foams age is a major determinant of the enrichment they display. It is argued that this period allows time for the seawater occluded in the interstitial spaces between bubbles, to drain away. Since foam production is ubiquitous over the oceans it seems likely that this process local to coastal environments is much more common than at first might appear to be the case. The paper explains how this work provides circumstantial evidence that the bubble-bursting mechanism current since the 1960s may well provide the iodine which appears to be missing in many modelling calculations based upon an atmospheric system dependant upon sorption of the species IO upon the marine aerosol.