Question: How can I test whether beach foam is natural or potential pollution?

bhamster is asking a question about water-quality
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by bhamster | June 23, 2020 21:35 | #24027

At several of the public coastal beaches in my city, water lapping at the shore or sitting around at low tide occasionally has a foamy border. Many of these beaches are at or near industrial sites (some active, some not). I'm wondering:

  • What kinds of tools or tests could be used to see whether the foam is naturally-occurring sea foam vs. pollution?

  • What specific things would I be looking for to distinguish the two?

The city has accessible channels for reporting pollution, so I'd be able to share info with them if the foam turns out to be questionable.

Thank you for any thoughts, ideas, or additional questions!


Hi bhamster ,

I don't have the answer to your question, but I researched it and found a paper about it:

Foam in the aquatic environment

Best Regards, Markos

@Markos Thanks so much for finding and sharing this paper on aquatic foam!

The paper helped me better understand that surface water foams can contain a combination of naturally-occurring and artificial compounds. So, declaring that it's either natural OR artificial would probably be a challenge. But, foams are a place where polluting chemicals (like pesticides or heavy metals) can build up. So maybe the question is more, “Are polluting chemicals present and how much is there?”

Another interesting highlight from the article is that even foams produced by natural sources can indicate a problem. For instance, excess fertilizer use can lead to algae blooms, which can create lots of foam. The foam itself might be from natural sources, but the natural sources are responding to an artificial, polluting situation.

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Thanks for the answer above. I want to ask the same question. Thanks you made my day!

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One way to get a rough idea of whether a foam is naturally-occurring or potential pollution is to poke it with a stick (much like the “stick test” for surface water sheens): “Poke foam with a stick and see if it breaks apart. If so, it’s probably natural!” (From this guide to spotting pollution from Re-Sources for Sustainable Communities in Bellingham, WA).

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@bhamster - when I'm doing my next Marine Debris Survey in the Tacoma Tideflats I definitely will try this out

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What about if it fluoresces under UV light? Could that help? Though some natural substances fluoresce too.

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