[hh3k0]

> The observation is from 1998 which I believe has relevance that would be curiously missing from the article?

What you're missing is that it's not an article, but an educational resource for kids in grade 3–12.

[blamazon]

That only makes me more upset! Why stifle the curiosity of kids that want to investigate the original sources of such information?

[ta1243]

It literally says it comes from the Deep-Sea Debris Database, it doesn't spoonfeed it by listing the specific reference, but a search for "mariana trench" and I can see a large variety of debris, including

Plastic bag/sheet (Several), Unidentified debris

Can

Beverage can

Other plastic product (Several)

etc

[vorticalbox]

I feel educational writing would be a better resource by listing their sources.