Astronomy

Marine foam

Marine foam

There are times when some seas seem to be more foamy than others; and is that certain factors combined can cause the waves to reach the beach with little foam, or it seems that we are contemplating the inside of a washing machine. But why does this happen? How different in composition are the marine waters of some seas with respect to those of others?

The truth is that no. Generally sea foam is similar to that found in beer or carbonated soft drinks; that is, they are air bubbles created by stirring the waters. Therefore, if the sea is very rough, the foam that is generated will be greater than if it is calm. Just shake a teaspoon in a glass of water to check. If, in addition, the temperature of the water is low, the foam will remain longer, since the gases do not escape into the atmosphere with such speed as when the sun warms more.

This was what happened on Kings Day this year 2014 in the picturesque fishing village of A Guarda (Galicia). The waves of even ten meters high threw the port and part of the town such an amount of cold foam that covered several tens of kilometers and gave rise to beautiful sunsets like the one shown in the image.

Another factor that contributes to the appearance of foam is the organic pollutants that rivers pour into the sea, loaded with fertilizers, fertilizers and detergents. When being agitated by the waves, they give rise to large masses of foam, just as if we put a dishwasher in a glass of water and then remove it with a teaspoon.

The presence of organic pollutants in the water in turn creates the proliferation of numerous microorganisms that return to denser waters, by multiplying and adding chemicals from their metabolism, which causes the foam to remain longer (they alter the surface tension of the water, that is, the resistance that water causes gases to escape into the atmosphere) while preventing the correct oxygenation of water making it insane for organisms that live there.

This usually happens every so often in Australia, leaving beaches covered by foam and organic pollutants as seen in the photograph. If we compare the foam of this image with that of the image of Galicia, we will observe that the contaminating foam can be easily distinguished by presenting the same appearance as that created by the gels in the shower or by household detergents. Why? Because they tend to be formed by the same substances.

As a curiosity, did you know that there is a type of white mineral known as Sea foam? It is very easy to carve and the old sailors used to use it to make smoking pipes. Although the formation of this mineral has nothing to do with the sea, it is a variety of sepiolite, its name is due to German sailors who possibly called it that way because of its whitish appearance and floating in the water, even more so if it is marine, denser because of the salts it contains.

By the way, sepiolite has proved surprisingly useful when there is a spillage of oil in the sea since it absorbs the pollutant while remaining afloat preventing it from being deposited in the bottom killing the animals that live there, at the same time which facilitates the removal of the contaminant from the water.

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