Biogenically driven organic contribution to marine aerosol

Abstract

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.

Aerosol and snow transfer processes: An investigation on the behavior of water-soluble organic compounds and ionic species

“…Ammonium was mainly distributed in the <0.49 mm fraction (Fig. S2), suggesting that its main source was the ocean (Jickells et al, 2003;O'Dowd et al, 2004;Johnson and Bell, 2008). The ionic composition, concentration and particle size distributions were similar to data obtained from the same sampling site during the austral summer of 2010e11 (Barbaro et al, 2017).…”

Marine aerosol production: a review of the current knowledge

“…The most comprehensive study to date on the organic fraction of sea-spray aerosol has been conducted by Cavalli et al (2004) and O'Dowd et al (2004). They found a significant and dominating fraction of organic matter in submicrometre sizes, while the supermicrometre size range was predominately inorganic sea salt.…”

Composition and evolution of volcanic aerosol from eruptions of Kasatochi, Sarychev and Eyjafjallajökull in 2008–2010 based on CARIBIC observations

“…The activity shows strong geographical and seasonal variations (Stramska, 2009). Measurements in Maze Head (Ireland) show organic aerosol concentration of several hundred ng m −3 connected with biologic activity in the ocean during spring to autumn (O'Dowd et al, 2004;Yoon et al, 2007). All three volcanoes studied here erupted in the biologically active part of the year.…”