Is it true that 80 percent of plastics in the ocean comes from land, 20 percent from the sea?

This claim is uncertain. We could find no credible scientific source to back up it up. The percentage of land- and sea-based plastic inputs into the ocean has not yet been calculated on a global level and therefore remains unknown. Scientific studies show that the ratio of land versus ocean-based plastics can differ strongly depending on the specific location and the scientific metric used.