Surfactant Scavenging and Surface Deposition by Rising Bubbles

Stefan, Ryan; Szeri, Andrew J.

doi:10.1006/jcis.1998.6037

Cited by 40 publications

(31 citation statements)

References 22 publications

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“…We contend that high EFs at such wind speeds should not be unexpected because it has long been known that the SML reforms rapidly following physical disruption [ Dragcevic and Pravdic , ], something we later confirmed experimentally with respect to SA [ Cunliffe et al ., ]. It is now well established that rapid SML recovery occurs because SML organics dispersed by breaking waves readily reabsorb to the surfaces of rising bubbles generated by the same breaking waves [ Stefan and Szeri , ; Woolf , ], to be released back to the SML and or ejected to air via bubble bursting at the air‐sea interface. Consequently, our data strongly support the notion of an essentially self‐sustaining SML and we have no reason to suspect that this mechanism would cease to operate either at or beyond the maximum wind speeds we observed.…”

Section: Discussionmentioning

confidence: 99%

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

Sabbaghzadeh

Upstill‐Goddard

Beale

et al. 2017

Geophysical Research Letters

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We report the first measurements of surfactant activity (SA) in the sea surface microlayer (SML) and in subsurface waters (SSW) at the ocean basin scale, for two Atlantic Meridional Transect from cruises 50°N to 50°S during 2014 and 2015. Northern Hemisphere (NH) SA was significantly higher than Southern Hemisphere (SH) SA in the SML and in the SSW. SA enrichment factors (EF = SASML/SASSW) were also higher in the NH, for wind speeds up to ~13 m s−1, questioning a prior assertion that Atlantic Ocean wind speeds >12 m s−1 poleward of 30°N and 30°S would preclude high EFs and showing the SML to be self‐sustaining with respect to SA. Our results imply that surfactants exert a control on air‐sea CO2 exchange across the whole North Atlantic CO2 sink region and that the contribution made by high wind, high latitude oceans to air‐sea gas exchange globally should be reexamined.

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Section: Discussionmentioning

confidence: 99%

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

Sabbaghzadeh

Upstill‐Goddard

Beale

et al. 2017

Geophysical Research Letters

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“…In both laboratory (Dragćević and Pravdić, 1981) and field (Williams et al, 1986) experiments, surface films appear to reform within seconds after disruption. In the presence of breaking waves, dispersed SML materials adsorb rapidly to the surface of the rising air bubbles, and therefore, bubble plumes may be the most important transport vector for surface-active material to the SML (Liss, 1975;Stefan and Szeri, 1999). When the bubble bursts at the sea-surface, only a fraction of attached organic matter is ejected into the air as aerosols, whereas the remainder is adsorbed on the surface to reform the SML (Liss, 1975).…”

Section: Evidence For Microlayer Enrichment At Higher Wind Speedsmentioning

confidence: 99%

“…Johnson and Cooke (1980) pointed out that the adsorption of surface-active compounds is selective, and compounds with higher surface activity have the highest potential to be scavenged and brought to the surface. Because even clean bubbles quickly become covered with surfactant while rising (Stefan and Szeri, 1999), globules of material may drop off the bottom of the bubbles, which could fractionate the material, leaving the most surface-active substances on the bubbles (GESAMP, 1995).…”

Section: Evidence For Microlayer Enrichment At Higher Wind Speedsmentioning

confidence: 99%

Formation and global distribution of sea-surface microlayers

et al. 2011

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Abstract.Results from a study of surfactants in the seasurface microlayer (SML) in different regions of the ocean (subtropical, temperate, polar) suggest that this interfacial layer between the ocean and atmosphere covers the ocean's surface to a significant extent. New, experimentally-derived threshold values at which primary production acts as a significant source of natural surfactants to the microlayer are coupled with a wind speed threshold at which the SML is presumed to be disrupted, and the results suggest that surfactant enrichment in the SML is greater in oligotrophic regions of the ocean than in more productive waters. Furthermore, surfactant enrichments persisted at wind speeds of up to 10 m s −1 , without any observed depletion above 5 m s −1 . This suggests that the SML is stable enough to exist even at the global average wind speed of 6.6 m s −1 . Using our observations of the surfactant enrichments at various trophic levels and wind states, global maps of primary production and wind speed allow us to extrapolate the ocean's SML coverage . The maps indicate that wide regions of the Pacific and Atlantic Oceans between 30 • N and 30 • S may be more significantly covered with SML than north of 30 • N and south of 30 • S, where higher productivity (spring/summer blooms) and wind speeds exceeding 12 m s −1 may prevent extensive SML formation.

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“…It should also be taken into account that the concentration of organic matter in the tank will evolve to a distribution characterized by the highest concentration near the water surface, as a result of the diffusion of surfactants to the air-water interface (Stefan and Szeri, 1999), thus, the shallow bubble plumes produced in our study spend their lifetime in the relevant region for organics adsorption. According to these results the differences observed between the different bubble-bursting mechanisms would not be related to the different bubble paths.…”

Section: Adsorption Kinetics Of Marine Surfactants On Rising Bubblesmentioning

confidence: 99%

“…We suggest that the higher number of bubbles generated by the 8 water jets system with respect to the spargers (estimated to be about double amount with respect to the glass frit) might explain the differences observed in the hygroscopicity and CCN measurements between the bubble-bursting systems. A higher number of bubbles imply more transport of organic matter to the water subsurface (Stefan and Szeri, 1999), which would lead to higher local organic concentration near the bubble bursting region and, hence, to higher particle organic enrichment. Further work with the same system and different bubble production should be conducted in order to clarify this aspect.…”

Section: Adsorption Kinetics Of Marine Surfactants On Rising Bubblesmentioning

confidence: 99%

Laboratory-generated primary marine aerosol via bubble-bursting and atomization

et al. 2010

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Abstract.A range of bubble and sea spray aerosol generators has been tested in the laboratory and compared with oceanic measurements from the literature. We have shown that the method of generation has a significant influence on the properties of the aerosol particles produced. Hence, the validity of a generation system to mimic atmospheric aerosol is dependent on its capacity for generating bubbles and particles in a realistic manner. A bubble-bursting aerosol generator which produces bubbles by water impingement was shown to best reproduce the oceanic bubble spectral shapes, which confirms previous findings.Two porous bubblers and a plunging-water jet system were tested as bubble-bursting aerosol generators for comparison with a standard nebulizer. The methods for aerosol production were evaluated by analysing the bubble spectrum generated by the bubble-bursting systems and the submicron size distribution, hygroscopicity and cloud condensation nucleus activity of the aerosols generated by the different techniques. Significant differences in the bubble spectrum and aerosol properties were observed when using different aerosol generators.The aerosols generated by the different methods exhibited similar hygroscopicity and cloud condensation nucleus activity behaviour when a sample of purely inorganic salts was used as a parent seawater solution; however, significant differences in the aerosol properties were found when using samples of filtered natural seawater enriched with biogenic organics. The presence of organics in the aerosol caused suppression of the growth factor at humidities above 75% RH and an increase in the critical supersaturation with respect Correspondence to: G. McFiggans (g.mcfiggans@manchester.ac.uk) to the generation from artificial seawater devoid of organics. The extent of the effect of organics on the aerosol properties varied depending on the method of particle production. The results of this work indicate that the aerosol generation mechanism affects the particles organic enrichment, thus the behaviour of the produced aerosols strongly depends on the laboratory aerosol generator employed.Comparison between bubble lifetimes in several laboratory simulations and the oceanic conditions indicated that it would require a considerable extension of the dimensions of the currently used bubble-bursting laboratory systems in order to replicate the characteristic oceanic bubble lifetimes. We analyzed the implications derived from the reduced bubble residence times in scaled systems, regarding marine surfactants adsorption on rising bubbles, and found that adsorption equilibrium is reached on a timescale much shorter than the bubble lifetime in small-scale laboratory generators. This implies that adsorption of marine surface-active material is not limited by surfactant transport to the bubble surface.

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Surfactant Scavenging and Surface Deposition by Rising Bubbles

Cited by 40 publications

References 22 publications

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

Formation and global distribution of sea-surface microlayers

Laboratory-generated primary marine aerosol via bubble-bursting and atomization

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Surfactant Scavenging and Surface Deposition by Rising Bubbles

Cited by 40 publications

References 22 publications

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s−1

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s−1

Formation and global distribution of sea-surface microlayers

Laboratory-generated primary marine aerosol via bubble-bursting and atomization

Contact Info

Product

Resources

About

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹