Is it true that 80% of marine debris comes from land and 20% comes from the ocean?
This statement is possible, but unknown. We have been looking into the origin of that figure. It’s frequently quoted in the press, but doesn’t appear often in scientific literature. A few times the results from the International Coastal Cleanup were cited as the source for these percentages; however if you take a look at the results from any given year, you will notice percentages differing from one place to another. Additionally, this event surveys primarily beach debris, and thus may overestimate land-based sources because of beachgoers’ litter. We also know relatively little about what is lying on the ocean floor or suspended in the water column. Because of this we truly can’t say what the land- and ocean-based percentages are with any certainty or accuracy. Just begin to think of all the debris types that sink (e.g., metal, dense plastics) in addition to all the ships on our ocean floor and you get the picture.
