[Zancarius]

I believe the article is talking about ephemeral debris that was sent into the ocean from the 2011 tsunami. What will happen to it in the next 10-20 years is anyone's guess, but factory chimneys aren't something that get thrown overboard or stuffed into municipal landfills.

What this does demonstrate is how one natural disaster can spread signs of human influence and decay for thousands of miles, and it will likely take decades for this stuff to degrade or disperse.