Investigating Primary Marine Aerosol Properties: CCN Activity of Sea Salt and Mixed Inorganic–Organic Particles

Abstract

Sea spray particles ejected as a result of bubbles bursting from artificial seawater containing salt and organic matter in a stainless steel tank were sampled for size distribution, morphology, and cloud condensation nucleus (CCN) activity. Bubbles were generated either by aeration through a diffuser or by water jet impingement on the seawater surface. Three objectives were addressed in this study. First, CCN activities of NaCl and two types of artificial sea salt containing only inorganic components were measured to establish a baseline for further measurements of mixed organic–inorganic particles. Second, the effect of varying bubble residence time in the bulk seawater solution on particle size and CCN activity was investigated and was found to be insignificant for the organic compounds studied. Finally, CCN activities of particles produced from jet impingement were compared with those produced from diffuser aeration. Analyses indicate a considerable amount of organic enrichment in the jet-produced particles relative to the bulk seawater composition when sodium laurate, an organic surfactant, is present in the seawater. In this case, the production of a thick foam layer during impingement may explain the difference in activation and supports hypotheses that particle production from the two methods of generating bubbles is not equal.

Primary marine aerosol emissions from the Mediterranean Sea during pre-bloom and oligotrophic conditions: correlations to seawater chlorophyll <i>a</i> from a mesocosm study

“…However, no clear difference was seen between the first (when the microlayer was present) and subsequent size distributions during a given microlayer enriched experiment. In past experiments, the addition of organics to bubbling experiments have shown changes in the size distribution (Sellegri et al, 2006), particle number concentration (Fuentes et al, 2010b;King et al, 2012;Tyree et al, 2007), and CCN activity Atmos. Chem.…”

“…Sellegri et al (2006) saw a log-normal mode amplitude shift towards smaller diameters with the addition of sodium dodecyl sulfate (SDS) to artificial seawater; Fuentes et al (2010b) observed similar behavior in tests with artificial seawater and biogenic exudates, while King et al (2012) saw an additional lognormal mode at 200 nm with the addition of organic material to artificial seawater. Water temperature has also shown an effect on aerosol size distribution and number concentration, though different groups have seen varying trends.…”

“…Previous studies have indicated changing size distribution with increasing organic material (Fuentes et al, 2010b;King et al, 2012;Sellegri et al, 2006). Sellegri et al (2006) saw a log-normal mode amplitude shift towards smaller diameters with the addition of sodium dodecyl sulfate (SDS) to artificial seawater; Fuentes et al (2010b) observed similar behavior in tests with artificial seawater and biogenic exudates, while King et al (2012) saw an additional lognormal mode at 200 nm with the addition of organic material to artificial seawater.…”

“…Moore et al (2011) performed laboratory experiments with NaCl or artificial seawater in combination with SDS, Synechococcus, Ostreococcus or oleic acid and found that 100× the normal organic concentration still did not affect the CCN activity or cloud formation properties. King et al (2012) tested artificial seawater with different organics (palmitic acid, sodium laurate, fructose, mannose, SDS) and found that the number concentration decreased with the presence of stronger surfactants, most likely due to surface layer stabilization. The CCN activity was dependent on the contribution of the varying salts in the particle phase rather than the organics.…”

Evolving research directions in Surface Ocean - Lower Atmosphere (SOLAS) science

“…[63] Nevertheless, large uncertainties in the number Credit: Surface Ocean-Lower Atmosphere Study Law SOLAS research directions production flux remain, [63] although recent results converge within a factor of 2-3. [75] Advances have also been made in our understanding of the effect of ocean-derived aerosols on climate, particularly with respect to the effects of OM on CCN production, [76][77][78] and on boundary layer chemistry. [79][80][81] There has also been recent recognition that particles of ,1 mm may be a significant source of CCN in marine regions, [70] that is potentially more important than the contribution from the oxidation of DMS.…”