The stuff of sea foam

I’ve heard a bunch of different hypotheses about what sea foam actually is, but no one - neither knowledgeable people nor oceanography texts, seems to agree on what exactly it is. I’m hoping someone here can tell me.

So far I’ve heard:

  1. That the stuff of sea foam is just plain old seawater surrounding bubbles of air that have been mixed into the water.

  2. That the stuff of sea foam is seawater, but that as it becomes an extremely thin layer around a bubble of air, more water evaporates and the salts that remain allow the sea foam to maintain its shape as it dries - thus giving you the dry sea foam that you might see blow across the beach in high wind.

  3. That the stuff of sea foam is nutrients from the seawater, which are better at forming a bubble shape than the water is.

  4. That the stuff of sea foam is the remains of plankton in the seawater - shells, oils, and all, the lipids in which allow it to form a bubble much like a soap bubble.

  5. That the stuff of sea foam is the products of decomposition of organisms from the ocean.

Everyone seems to agree that sea foam is caused by the turbulent mixing of air and water in the surf zone, in storms, and occasionally where bodies of water converge.

So is it one, none, or more than one of the above?

If you could also cite your sources so I could check this out in more depth, I would greatly appreciate that :)!

All sorts of stuff gets concentrated in the sea’s surface microlayer. The exact composition varies from place to place and time to time. That said, plain old salt water does not form long lasting bubbles, so there must be something extra in sea foam that acts as a stabilizer. Carbohydrate slime and proteins from sea creatures would do the trick nicely.

If you are asking about meerschaum (= German "sea foam’) it is a a clay type mineral, hydrous magnesium silicate. Popular for making frou frou pipes for smoking.

From the Britannica: “Meerschaum (German: “sea-foam”), a fibrous hydrated magnesium silicate that is opaque and white, grey, or cream in colour. It may resemble the bones of the cuttlefish Sepia, from which the name derives. In the Black Sea region, where the light, porous clay mineral is abundant, it is said to resemble sea-foam, hence the German name.”

Thanks for the replies. I was asking about ocean foam, rather than the mineral, but now I know more about the mineral than I ever did before! (I’d never heard of it :wink: )

I suppose carbohydrates and proteins would do the job nicely; but do they? Surely someone out there has taken some sea foam and figured out what was in it.

Admittedly, it may vary in composition from place to place, but like seawater, it probably also has many similarities from place to place.

Uh Oh…

No information from the Teeming Millions on this subject? :frowning:

Salt water aquariums use devices called “protein skimmers”, which are supposed to mimic the same effect as waves on the beach to remove organic materals from the water. They work by injecting millions of fine air bubbles into a column of seawater, creating a thick foam that gets skimmed off the top into a drain. Apparantly when you mix air bubbles into salty water, all kinds of polar molecules get concentrated inthe resulting foam, and increase the surface tension, allowing the foam to persist and be mechanically seperated.

So, the sea foam is made from saltwater with many tiny air bubbles mixed in, with a concentration of organic molecules (proteins, and stuff) adding extra surface tension.