Biogenically driven organic contribution to marine aerosol.
Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centred on the production of aerosol from sea-salt and non-sea-salt sulphates. Recent field experiments, however, have shown that known aerosol production processes for inorganic species cannot account for the entire aerosol mass that occurs in submicrometre sizes. Several experimental studies have pointed to the presence of significant concentrations of organic matter in marine aerosol. There is some information available about the composition of organic matter, but the contribution of organic matter to marine aerosol, as a function of aerosol size, as well as its characterization as hydrophilic or hydrophobic, has been lacking. Here we measure the physical and chemical characteristics of submicrometre marine aerosol over the North Atlantic Ocean during plankton blooms progressing from spring through to autumn. We find that during bloom periods, the organic fraction dominates and contributes 63% to the submicrometre aerosol mass (about 45% is water-insoluble and about 18% water-soluble). In winter, when biological activity is at its lowest, the organic fraction decreases to 15%. Our model simulations indicate that organic matter can enhance the cloud droplet concentration by 15% to more than 100% and is therefore an important component of the aerosol-cloud-climate feedback system involving marine biota.
Department of Experimental Physics and Environmental Change Institute, National University of Ireland, Galway, Ireland.
Colin D
CD
O'Dowd
Maria Cristina
MC
Facchini
Fabrizia
F
Cavalli
Darius
D
Ceburnis
Mihaela
M
Mircea
Stefano
S
Decesari
Sandro
S
Fuzzi
Young Jun
YJ
Yoon
Jean-Philippe
JP
Putaud
D000336:Aerosols / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D001267:Atlantic Ocean; D001272:Atmosphere / Q000737:chemistry*; D018533:Biomass; D002734:Chlorophyll / Q000032:analysis; D002980:Climate; D025461:Feedback, Physiological; D008386:Marine Biology; D008970:Molecular Weight; D010933:Plankton / Q000378:metabolism*; D012621:Seasons; D012623:Seawater / Q000737:chemistry; D012995:Solubility
D000336:Aerosols; D002734:Chlorophyll