[1] The chemical properties of sea-spray aerosol particles produced by artificially generated bubbles using oceanic waters were investigated during a phytoplankton bloom in the North Atlantic. Spray particles exhibited a progressive increase in the organic matter (OM) content from 3 ± 0.4% up to 77 ± 5% with decreasing particle diameter from 8 to 0.125 mm. Submicron OM was almost entirely water insoluble (WIOM) and consisted of colloids and aggregates exuded by phytoplankton. Our observations indicate that size dependent transfer of sea water organic material to primary marine particles is mainly controlled by the solubility and surface tension properties of marine OM. The pattern of WIOM and sea-salt content in the different size intervals observed in bubble bursting experiments is similar to that measured in atmospheric marine aerosol samples collected during periods of high biological activity. The results point to a WIOM/sea-salt fingerprint associated with submicron primary marine aerosol production in biologically rich waters. Citation: Facchini, M. C., et al.

Abstract. Air-sea fluxes and bulk seawater and atmospheric concentrations of bromoform (CHBr 3 ) and dibromomethane (CH 2 Br 2 ) were measured during two research cruises in the northeast Atlantic (53-59 • N, June-July 2006) and tropical eastern Atlantic Ocean including over the African coastal upwelling system (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) • N May-June 2007). Saturations and sea-air fluxes of these compounds generally decreased in the order coastal > upwelling > shelf > open ocean, and outside of coastal regions, a broad trend of elevated surface seawater concentrations with high chlorophyll-a was observed. We show that upwelling regions (coastal and equatorial) represent regional hot spots of bromocarbons, but are probably not of major significance globally, contributing at most a few percent of the total global emissions of CHBr 3 and CH 2 Br 2 . From limited data from eastern Atlantic coastlines, we tentatively suggest that globally, coastal oceans (depth <180 m) together contribute ∼2.5 (1.4-3.5) Gmol Br yr −1 of CHBr 3 , excluding influences from anthropogenic sources such as coastal power stations. This flux estimate is close to current estimates of the total open ocean source. We also show that the concentration ratio of CH 2 Br 2 /CHBr 3 in seawater is a strong function of concentration (and location), with a lower CH 2 Br 2 /CHBr 3 ratio found in coastal regions near to macroalgal sources.

[1] Volatile organoiodine compounds (VOIs) are the main carrier of iodine from the oceans to the atmosphere. We have identified a novel, sea-surface source of the short-lived VOIs CH 2 I 2 , CHClI 2 and CHI 3 in a series of laboratory experiments. These compounds were formed when seawater, collected during winter in the North Sea, was exposed to ambient levels of ozone. The VOIs are produced from the reaction of marine dissolved organic matter with hypoiodous acid/molecular iodine, which are formed at the sea surface when ozone reacts with dissolved iodide. The same three VOIs were formed when we incubated seawater of different productivity levels with molecular iodine during a cruise in the tropical Atlantic Ocean. We suggest that the presence of dissolved iodide, dissolved organic matter and ozone can lead to the sea-surface production of CH 2 I 2 , CHClI 2 and CHI 3 . As such, this process could provide a ubiquitous source of iodine to the marine atmosphere.