title: Marine aerosol formation from biogenic iodine emissions.
abstract: The formation of marine aerosols and cloud condensation nuclei--from which marine clouds originate--depends ultimately on the availability of new, nanometre-scale particles in the marine boundary layer. Because marine aerosols and clouds scatter incoming radiation and contribute a cooling effect to the Earth's radiation budget, new particle production is important in climate regulation. It has been suggested that sulphuric acid derived from the oxidation of dimethyl sulphide is responsible for the production of marine aerosols and cloud condensation nuclei. It was accordingly proposed that algae producing dimethyl sulphide play a role in climate regulation, but this has been difficult to prove and, consequently, the processes controlling marine particle formation remains largely undetermined. Here, using smog chamber experiments under coastal atmospheric conditions, we demonstrate that new particles can form from condensable iodine-containing vapours, which are the photolysis products of biogenic iodocarbons emitted from marine algae. Moreover, we illustrate, using aerosol formation models, that concentrations of condensable iodine-containing vapours over the open ocean are sufficient to influence marine particle formation. We suggest therefore that marine iodocarbon emissions have a potentially significant effect on global radiative forcing.
authors.affiliation: Department of Physics, National University of Ireland, Galway, Ireland.colin.odowd@cmas.demon.co.uk
authors.forename: Colin D
authors.initials: CD
authors.lastname: O'Dowd
authors.forename: Jose L
authors.initials: JL
authors.lastname: Jimenez
authors.forename: Roya
authors.initials: R
authors.lastname: Bahreini
authors.forename: Richard C
authors.initials: RC
authors.lastname: Flagan
authors.forename: John H
authors.initials: JH
authors.lastname: Seinfeld
authors.forename: Kaarle
authors.initials: K
authors.lastname: Hämeri
authors.forename: Liisa
authors.initials: L
authors.lastname: Pirjola
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.forename: S Gerard
authors.initials: SG
authors.lastname: Jennings
authors.forename: Thorsten
authors.initials: T
authors.lastname: Hoffmann
mesh_terms: D000336:Aerosols / Q000737:chemistry* / Q000378:metabolism* / Q000528:radiation effects; D001272:Atmosphere / Q000737:chemistry*; D002980:Climate; D056890:Eukaryota / Q000378:metabolism*; D017709:Fractals; D005740:Gases / Q000378:metabolism / Q000528:radiation effects; D007455:Iodine / Q000378:metabolism* / Q000528:radiation effects; D008954:Models, Biological; D010316:Particle Size; D010782:Photolysis / Q000528:radiation effects; D012623:Seawater; D014466:Ultraviolet Rays; D014835:Volatilization / Q000528:radiation effects; D014887:Weather
chemical_list: D000336:Aerosols; D005740:Gases; D007455:Iodine