The 10 rivers that carry 93 percent of that trash are the Yangtze, Yellow, Hai, Pearl, Amur, Mekong, Indus and Ganges Delta in Asia, and the Niger and Nile in Africa. The Yangtze alone dumps up to an estimated 1.5 million metric tons of plastic waste into the Yellow Sea.
https://www.scientificamerican.com/article/stemming-the-plastic-tide-10-rivers-contribute-most-of-the-plastic-in-the-oceans/