[semimojo]

The glass, metal, and plastic will join the sand as a part of the beach over time, and ultimately be buried in sediment. In that state the trash does not pose any particular risk to people, animals, or plants.

Not sure what your basis for this claim is, but storms and wave action can erode beaches and put this debris back into the ocean,

More to the point, what about all of the debris that didn’t make it to the island and is being ingested by or entangling aquatic wildlife?

[freeandfreezing]

I'm not suggesting that putting trash in the ocean is a good idea, it obviously isn't. See my earlier posts, and make sure you don't throw trash into rivers or the ocean. I doubt that you do.

Unfortunately people in Asia do throw their trash into rivers, which ends up in the ocean. Teaching them not to do so would be helpful to the marine ecosystems.

The original research paper describes the process of trash being reduced to smaller particles, and basic geology teaches us that erosion grinds up larger objects, including rocks, into fine particles. That is how sand beaches are created in the first place. Fine particles, whether they are from rocks, sea shells, dinosaur bones, dishes, or plastic trash end up as sand or sediments and ultimately are buried.

Storms and erosion can put all of the materials on the beach back into the ocean, at least temporarily. But trash on a remote beach, particularly the buried trash, is less of a hazard to wildlife than floating trash. Put simply - if you find a bunch of buried trash on a beach don't throw it into the ocean since buried in the beach is a better place than the ocean for it to be.