Sea foam reveals a lot about the health of a beach’s ecosystem. Here’s how to spot polluted surf

A simple stroll along a beach on a windy day can be mesmerising. It’s easy to spend hours watching waves crash and sea foam fizz across the sand, but this beautiful yet fleeting phenomenon can also give us clues about the health of the ocean.

Sea foam is produced by the turbulence caused by the force of the waves and the wind which, when combined with organic matter (mainly plankton), forms a mixture of water and air bubbles that clump together and rise to the surface as foam.

This colloidal…

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