Wind-induced collapse of the biopolymeric surface microlayer induces sudden changes in sea surface roughness.
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| Title: | Wind-induced collapse of the biopolymeric surface microlayer induces sudden changes in sea surface roughness. |
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| Authors: | Engel, Anja1,2 (AUTHOR) aengel@geomar.de, Friedrichs, Gernot1,3,4 (AUTHOR), Krall, Kerstin E.5 (AUTHOR), Jähne, Bernd5,6 (AUTHOR) |
| Source: | Biogeosciences. 2026, Vol. 23 Issue 6, p2101-2117. 17p. |
| Subject Terms: | *Sea surface microlayer, *Surface roughness, *Surface active agents, *Ocean-atmosphere interaction, *Wind speed, *Biopolymers, *Polypeptides, *Polysaccharides |
| Abstract: | All exchange between the ocean and atmosphere has to cross the sea surface microlayer (SML), yet the SML impact on modulating air-sea exchange rates remains poorly understood. Surfactants, including biopolymers, can influence exchange rates by altering the rheological properties of the SML, damping surface turbulence, and capillary wave formation. We investigated the impact of wind speed on SML biopolymer enrichment, surface roughness, and interfacial surfactant coverage at the Heidelberg "Aeolotron", a large annular wind-wave facility filled with 18 000 L seawater. Our results show that biopolymer enrichment, specifically the enrichment of polypeptides and polysaccharides, in the SML declined sharply at wind speeds above 6 m s−1, coinciding with a sudden increase in the Mean Square Slope (MSS) of waves by 1–2 orders of magnitude. At wind speed < 6 m s−1, biopolymer enrichment in the SML was accompanied by high surfactant surface coverage and strongly reduced MSS values compared to non-enriched or essentially surfactant-free clean freshwater surfaces, indicating a substantial impact of biopolymer enrichment in the SML for air-sea exchange at lower wind speed. Selective SML enrichment was observed, particularly for the amino acids arginine and glutamic acid, and the amino sugar galactosamine. Amino acid and carbohydrate monomers in the SML also exhibited significant and compound-specific wind-induced variability. Our findings suggest that biopolymers, particularly those derived from bacterial production, accumulate in the SML and act as powerful biosurfactants. Unlike artificial surfactant films, natural SML components were more susceptible to wind-induced disruption and to microbial production and decomposition. Our findings reveal that ecological processes actively regulate the chemical and physical properties of the SML, including surfactant surface coverage, and thereby potentially modulate air–sea heat and mass exchange. [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 192903900 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Wind-induced collapse of the biopolymeric surface microlayer induces sudden changes in sea surface roughness. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Engel%2C+Anja%22">Engel, Anja</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> aengel@geomar.de</i><br /><searchLink fieldCode="AR" term="%22Friedrichs%2C+Gernot%22">Friedrichs, Gernot</searchLink><relatesTo>1,3,4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Krall%2C+Kerstin+E%2E%22">Krall, Kerstin E.</searchLink><relatesTo>5</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Jähne%2C+Bernd%22">Jähne, Bernd</searchLink><relatesTo>5,6</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Biogeosciences%22">Biogeosciences</searchLink>. 2026, Vol. 23 Issue 6, p2101-2117. 17p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Sea+surface+microlayer%22">Sea surface microlayer</searchLink><br />*<searchLink fieldCode="DE" term="%22Surface+roughness%22">Surface roughness</searchLink><br />*<searchLink fieldCode="DE" term="%22Surface+active+agents%22">Surface active agents</searchLink><br />*<searchLink fieldCode="DE" term="%22Ocean-atmosphere+interaction%22">Ocean-atmosphere interaction</searchLink><br />*<searchLink fieldCode="DE" term="%22Wind+speed%22">Wind speed</searchLink><br />*<searchLink fieldCode="DE" term="%22Biopolymers%22">Biopolymers</searchLink><br />*<searchLink fieldCode="DE" term="%22Polypeptides%22">Polypeptides</searchLink><br />*<searchLink fieldCode="DE" term="%22Polysaccharides%22">Polysaccharides</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: All exchange between the ocean and atmosphere has to cross the sea surface microlayer (SML), yet the SML impact on modulating air-sea exchange rates remains poorly understood. Surfactants, including biopolymers, can influence exchange rates by altering the rheological properties of the SML, damping surface turbulence, and capillary wave formation. We investigated the impact of wind speed on SML biopolymer enrichment, surface roughness, and interfacial surfactant coverage at the Heidelberg "Aeolotron", a large annular wind-wave facility filled with 18 000 L seawater. Our results show that biopolymer enrichment, specifically the enrichment of polypeptides and polysaccharides, in the SML declined sharply at wind speeds above 6 m s−1, coinciding with a sudden increase in the Mean Square Slope (MSS) of waves by 1–2 orders of magnitude. At wind speed < 6 m s−1, biopolymer enrichment in the SML was accompanied by high surfactant surface coverage and strongly reduced MSS values compared to non-enriched or essentially surfactant-free clean freshwater surfaces, indicating a substantial impact of biopolymer enrichment in the SML for air-sea exchange at lower wind speed. Selective SML enrichment was observed, particularly for the amino acids arginine and glutamic acid, and the amino sugar galactosamine. Amino acid and carbohydrate monomers in the SML also exhibited significant and compound-specific wind-induced variability. Our findings suggest that biopolymers, particularly those derived from bacterial production, accumulate in the SML and act as powerful biosurfactants. Unlike artificial surfactant films, natural SML components were more susceptible to wind-induced disruption and to microbial production and decomposition. Our findings reveal that ecological processes actively regulate the chemical and physical properties of the SML, including surfactant surface coverage, and thereby potentially modulate air–sea heat and mass exchange. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.5194/bg-23-2101-2026 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 17 StartPage: 2101 Subjects: – SubjectFull: Sea surface microlayer Type: general – SubjectFull: Surface roughness Type: general – SubjectFull: Surface active agents Type: general – SubjectFull: Ocean-atmosphere interaction Type: general – SubjectFull: Wind speed Type: general – SubjectFull: Biopolymers Type: general – SubjectFull: Polypeptides Type: general – SubjectFull: Polysaccharides Type: general Titles: – TitleFull: Wind-induced collapse of the biopolymeric surface microlayer induces sudden changes in sea surface roughness. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Engel, Anja – PersonEntity: Name: NameFull: Friedrichs, Gernot – PersonEntity: Name: NameFull: Krall, Kerstin E. – PersonEntity: Name: NameFull: Jähne, Bernd IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 03 Text: 2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 17264170 Numbering: – Type: volume Value: 23 – Type: issue Value: 6 Titles: – TitleFull: Biogeosciences Type: main |
| ResultId | 1 |
