These plastic wastes are gradually broken up in the marine environment, forming a large number of microplastics with a diameter of less than 5 mm, which is called "PM2.5 in the ocean" by scientists. Every year, about millions of tons of plastic waste enter the ocean under the action of wind, precipitation, surface runoff, etc. Large pieces of plastic waste are gradually aged, broken and decomposed by the action of light, waves, and organisms to form microplastics that are difficult to observe with the naked eye. In addition, fibers from clothes, rubber particles from tire wear, plastic-containing dust, and plastic microbeads added to cosmetics such as facial cleanser and toothpaste are also important sources of marine microplastics.
