Isolation of marine microlayer film surfactants for ex situ study of their surface physical and chemical properties

Frew, Nelson M.; Nelson, Robert K.

doi:10.1029/91jc02724

Cited by 32 publications

(21 citation statements)

References 19 publications

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“…This work points out the need for a study comparing near‐shore and off‐shore bubble dissolution behavior with simultaneous organic compositional analysis. Indeed, Frew and Nelson [1992a, 1992b] found differences in the C/N ratio and surface behavior of onshore and offshore sea slick microlayers. Interestingly, their P‐A characteristics were both similar to an expanded phase lipid or fatty acid monolayer, but the offshore samples exhibit generally higher elastic moduli.…”

Section: Discussionsupporting

confidence: 92%

Dissolution of microbubbles generated in seawater obtained offshore: Behavior and surface tension measurements

2007

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[1] Ocean water samples were collected from Saint Andrew Bay and the Gulf of Mexico near Panama City, Florida, on board the R/V Athena. Optical microscopy observations of the dissolution of microbubbles generated in these water samples showed that the microbubbles remained spherical and their surfaces remained smooth during dissolution. Comparatively, these bubbles behaved like bubbles coated with expanded phase surfactants, as we show by directly observing the dissolution of sodium dodecyl sulfate (SDS) bubbles and citing our previous work involving dissolution of short-chain lipidcoated microbubbles. We apply Epstein and Plesset's model for the dissolution of a 15 to 25 mm radius microbubble to determine surface tension, appropriate for a dissolving bubble coated with expanded phase surfactant. Average surface tensions of dissolving bubbles obtained in multiple locations and from two depths (from the sea-air surface and 10 feet (1 foot = 0.3048 m) below the sea-air surface) range between 21 and 37 dyn/cm with a resulting dissolution time of at least 2 times that of a clean microbubble at an initial radius of 15 mm. We never observed a remnant particle upon completion of dissolution, consistent with the observed smooth dissolution. These visual observations are in contrast to several studies involving visual observations of dissolution of seawater microbubbles. Reasons for these differences are postulated. Generally, our results are consistent with microbubbles coated primarily with short-chain and unsaturated fatty acids or lipids, but with a minority fraction of a long-chain component, all remaining in an expanded phase. Similarities in occasional dimpled morphology and surface tension with SDS/1,2-dipalmitoyl-sn-glycero-3-phosphocholine -coated bubbles are used to come to this conclusion.Citation: Lozano, M. M., E. Talu, and M. L. Longo (2007), Dissolution of microbubbles generated in seawater obtained offshore: Behavior and surface tension measurements,

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Section: Discussionsupporting

confidence: 92%

Dissolution of microbubbles generated in seawater obtained offshore: Behavior and surface tension measurements

2007

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“…In Figure 3 we have plotted C/N weight ratios static elastic properties of marine films. We have previously shown for a detailed set of measurements on a suite of samples collected in the southern California Bight that chemical heterogeneity is expressed in the •-A isotherms for different slicks [Frew and Nelson, 1992b]. For well-developed slicks, we identified two different film types as evidenced by the grouping of their isotherms.…”

Section: Static Surface Elasticity In Multicomponent Filmsmentioning

confidence: 89%

Static and dynamic response of natural multicomponent oceanic surface films to compression and dilation: Laboratory and field observations

Bock¹,

Frew²

1993

J. Geophys. Res.

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The quasi-static elasticity (Gibbs' elasticity) of sea surface films collected in North American coastal waters has been examined using a large number of surface pressure-area isotherms. The films examined show considerable variability in elastic properties. Differences among films appear to be the result of chemical variability due to differences in source; they are also affected by dynamic physical processes (e.g., film compression). Elasticities of adsorbed films from subsurface and microlayer water are observed to exhibit a bimodal distribution at 0.5 mN m 4 reference spreading pressure; films from organized banded slicks are shown to have generally higher elastic moduli. Mechanisms of surface selectivity and competitive adsorption are suggested to explain this effect; results of film aging and work hardening studies are presented in support. Significant hysteresis effects are observed for cyclical compression and dilation of the films suggesting the prevalence of relaxation processes that lead to compositional changes and higher elastic moduli. Field measurements of capillary and ripple spectra are presented to infer information on wave damping and dynamic viscoelasticity. Results obtained in regions where surface convergence is absent imply damping enhancement over a broad frequency range consistent with theory for films of low elastic moduli. Films found in surface convergence zones, the result of surface upwelling, exhibit damping enhancements consistent with higher elastic moduli. Damping maxima are observed in multiple frequency bands; this banding is not readily explained with current theories. Results similar to these have been observed in laboratory studies with other chemical systems. In both the laboratory and field experiments, the tendency of the films to group into a few subsets with similar surface characteristics implies that natural films might be modeled by a small number of representative end members. This would facilitate remote sensing applications by providing a basis for determining the effects of films on surface waves under various conditions (e.g., diurnal variation, history of variability of wind stress).

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“…This is the reason why areas in -A isotherms of natural films are usually scaled as a trough area in cm 2 and not as area/molecule in Å 2 or nm 2 . However, Frew and Nelson (34,35) recently developed a method for isolating marine microlayer slick surfactants by solid phase adsorption using reversed (C18) cartridges. Lipid content was examined and the -A isotherms of microlayer films could be for the first time expressed on a specific area basis.…”

Section: Monolayer Study Of Reconstructed Sea Surface Microlayersmentioning

confidence: 99%

Physicochemical Characterization of Natural andex-SituReconstructed Sea-Surface Microlayers

Gašparović

Kozarac

Saliot

et al. 1998

Journal of Colloid and Interface Science

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Running title: Sea-surface microlayers 2 Chemical composition and physico-chemical characteristics of natural and ex-situ reconstructed sea surface microlayer samples were studied using a complex methodological approach. Surface microlayer samples and the underlying seawater were collected in different seasons and different weather conditions in the northern most part of the Adriatic sea. The techniques used were thin layer chromatography with flame ionization detection for lipid classes analysis, electrochemical characterization of adsorbable organic substances using the ONP probe and monolayer techniques for surface pressure () and surface potential ( V) measurements, as well as Brewster angle microscopy.Our results indicated higher enrichment of organic matter for the microlayer sample collected in the warm period of the year (summer). This was reflected in the high surface activity of the present organic substances, and formation of a more condensed layer than for the other two samples collected in the spring. Of the two spring samples, the one sampled on a sunny day was reacher in surface active organic material. We concluded that the most important source of surface active substances is the insitu production of organic susbtances by the present plankton and bacteria, promoted by sunlight, while antrophogenic input comprises a smaller part of the present organic matter, around 10 % for all samples.Key Words: sea-surface microlayer; lipid analysis; o-nitrophenol; surface active organic substances; voltammetry; monolayer studies; Brewster angle microscopy; northern Adriatic. 3 INTRODUCTIONSea surface microlayer is an important boundary, as an area of exchange of matter and energy, that either affects or is affected by global change (1, 2). Sea surface layer is generally enriched in organic substances, particularly those which are surface active, metal ions, bacteria and other microorganisms, relative to subsurface water (3-5). Organic substances found in the microlayer originate from the in-situ production or from different sources and have been brought there by different transport mechanisms from the seawater bulk, atmosphere or land. Adsorbed organic substances change the physical and optical properties, depending on the nature of organics, i.e. the nature of polar groups, architecture of the hydrophobic chain, and ionic strength, pH and temperature.Although the physical and chemical properties of the sea-surface microlayer have been studied extensively, there is still lack of knowledge about the physico-chemical processes governing the formation and properties of the surface microlayer.Electrochemical methods have been widely used for the investigation of surface active substances (SAS) in different waters (6 -9). These methods are based on the principle that organic substances adsorbed on the electrode surface influence the mass and charge transport across such a modified phase boundary. The recently developed electrochemical method using the o-nitrophenol (ONP) probe as a convenient tool for rough char...

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Isolation of marine microlayer film surfactants for ex situ study of their surface physical and chemical properties

Cited by 32 publications

References 19 publications

Dissolution of microbubbles generated in seawater obtained offshore: Behavior and surface tension measurements

Dissolution of microbubbles generated in seawater obtained offshore: Behavior and surface tension measurements

Static and dynamic response of natural multicomponent oceanic surface films to compression and dilation: Laboratory and field observations

Physicochemical Characterization of Natural andex-SituReconstructed Sea-Surface Microlayers

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