I would say it might be energies produced by the ocean and mixing with your own energy flow. The beach is a very charged place.

Also there are phosphorus chemicals in the ocean as seen below in the link.

https://www.google.com/search?q=phosphorus+ocean+waves&rlz=1C1SFXN_enUS50 1US502&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizyYOu 0ZbhAhV2HzQIHbT5A_cQ_AUIDigB&biw=1536&bih=706

Very cool stuff. Both energy and phosphorus.
It may be a combination of them also.

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