Aside: as far as I can tell, the factoid as usually stated is not true. It should be "90% of Ocean plastic that comes from rivers comes from just 10 rivers" and not "90% of all ocean plastic comes from rivers."

There's a graph from the paper (and the name of the paper) here that shows how much ocean plastic is from rivers; it's a lot but not 90% https://www.scientificamerican.com/article/stemming-the-plas...