15 July 2016

Sticky Organic Ocean Spray

Researchers find that the stickiness of organic molecules may increase their presence in sea spray.

Illustration of the single-component insoluble monolayer (left) and the formation of a second layer by soluble sugars sticking to the monolayer. Bottom: Potential impact of the two-layer treatment on organic mass fraction of sea spray in the OCEANFILMS model.
Science

Analysis of sea spray samples collected onboard ships has shown that they contain a large amount of saccharides (sugar-like molecules). However, because saccharides dissolve easily in water rather than staying on the surface like oils, it was unclear until now how this material entered the spray.

Impact

New research shows how, by sticking to oily substances floating on the water’s surface, saccharides might be able to accumulate at the ocean’s surface and be emitted to the atmosphere in sea spray. These interactions between saccharides and other molecules could resolve the question of how soluble saccharides enter sea spray.

Summary

A team of researchers from Pacific Northwest National Laboratory, Montana State University, and Los Alamos National Laboratory investigated the interactions between saccharides and fatty acids (oily molecules that are insoluble in water) on a water surface.

Spectroscopy experiments performed by Montana State University researchers and staff at DOE’s EMSL facility showed that saccharides can adsorb (stick) to the bottom of a layer of fatty acids that coats the water surface. This adsorption causes additional saccharide molecules to be present at the water’s surface. When the layer of fatty acids was not present, the saccharide molecules dissolved in the water. Because sea spray aerosol forms from the surface layer of ocean water, mechanisms similar to the one investigated in this study could increase the amount of organic matter emitted in sea spray.

Using a model developed at PNNL and Los Alamos, researchers tested the sensitivity of modeled sea spray composition to this mechanism. They found that if the molecules adsorb strongly enough, the amount of organic matter emitted in sea spray could be substantially increased. These emissions of organic matter could potentially impact the amount of sunlight that is reflected by clouds that are influenced by this spray.

Contact
Susannah Burrows
Pacific Northwest National Laboratory (PNNL)