Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 2.539 IF 2.539
  • IF 5-year value: 3.129 IF 5-year
    3.129
  • CiteScore value: 2.78 CiteScore
    2.78
  • SNIP value: 1.217 SNIP 1.217
  • IPP value: 2.62 IPP 2.62
  • SJR value: 1.370 SJR 1.370
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 48 Scimago H
    index 48
  • h5-index value: 32 h5-index 32
Discussion papers
https://doi.org/10.5194/os-2019-87
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-2019-87
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 01 Aug 2019

Submitted as: research article | 01 Aug 2019

Review status
This discussion paper is a preprint. It has been under review for the journal Ocean Science (OS). A final paper in OS is not foreseen.

The Determination of Surfactants at the Sea Surface

Leon King, Ieuan J. Roberts, Liselotte Tinel, and Lucy J. Carpenter Leon King et al.
  • Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, YO10 5DQ, UK

Abstract. The surface of the ocean is a critical yet little understood interface that covers more than 70 % of the Earth's surface. Evidence is emerging that the so-called sea surface microlayer (SML) – the thin film of the ocean surface which is enriched in surface active material and contains large chemical, physical and biological gradients that separate it from the underlying seawater – plays an important role in regulating the air-sea exchange of gases and aerosols. Indeed, recent studies have suggested that (a) there is a ubiquitous enrichment of surfactants in the SML even at high wind speeds; (b) surfactants exert a control on air-sea CO2 exchange at the ocean basin scale, even at high wind, high latitude oceans, and (c) interfacial photochemistry within the SML serves as a major global abiotic source of volatile organic compounds (VOCs), competitive with emissions from marine biology. These conclusions are based on measurements of surfactant activity (SA) from alternating current (AC) voltammetry, showing enrichment of SA in the SML compared to subsurface waters at the ocean basin scale even at high wind speeds, and a relationship between SA and suppression of air-sea gas exchange. SA is calibrated using the large non-ionic surfactant Triton X-100 (TX-100) and expressed in concentration units of TX-100 equivalents. Here, we show that the response of SA-voltammetry varies widely for different surfactants, depending on the surfactant's molecular weight and its charge. Further, even at short deposition times of 15 s, the response becomes saturated above total surfactant concentrations of 1–2 mg L-1, which are at the high end of those observed in the SML. This behaviour was also observed when comparing measurements of seawater and lake water by SA voltammetry to surface film pressure (Δγ) measured by tensiometry. These two different methods for assessing the presence of surfactants showed that, while SA generally increases as surface film pressure increases, the correlation is poor and SA values plateau above ∼2 mg L-1 TX-100 eq. The implications of these results are that SA might not accurately capture variations in soluble and insoluble surfactants present in ocean waters.

Leon King et al.
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Leon King et al.
Leon King et al.
Viewed  
Total article views: 240 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
192 47 1 240 4 5
  • HTML: 192
  • PDF: 47
  • XML: 1
  • Total: 240
  • BibTeX: 4
  • EndNote: 5
Views and downloads (calculated since 01 Aug 2019)
Cumulative views and downloads (calculated since 01 Aug 2019)
Viewed (geographical distribution)  
Total article views: 112 (including HTML, PDF, and XML) Thereof 111 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 21 Oct 2019
Publications Copernicus
Download
Short summary
Recent studies suggest that the sea surface microlayer is ubiquitously enriched in surfactants, even at high wind speeds, which exert a control on air-sea gas exchange. These conclusions are partly based on voltammetry measurements of surfactant activity (SA). Here, we show that the response of SA-voltammetry varies widely for different surfactants, becomes saturated above total surfactant concentrations of 1–2 mg L-1, and shows a poor correlation in natural waters with surface film pressure.
Recent studies suggest that the sea surface microlayer is ubiquitously enriched in surfactants,...
Citation