A 12-year-old girl from Andover, Massachusetts, is getting a big prize and national recognition for her invention to clean up the world's oceans.

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Anna Du is one of 10 finalists for the Discovery Education 3M Young Scientist Challenge for her work on an invention that detects microplastics in bodies of water without disturbing plants or animals.

"One day when I was at Boston Harbor, I noticed there was a lot of plastics on the sand," Du said. "I tried picking some up, but there seemed to be so many more, and it just seemed impossible to clean it all up."

Du, a lover of marine animals, decided to take action.

She began work on an underwater device that uses infrared light to detect harmful microplastics in the ocean.

Her invention is now gaining national attention as a finalist in the challenge.

As a finalist, Du will get a chance to work with one of 3M's scientists to take her invention from detecting plastic in her backyard, to detecting it in the world's oceans.

"Science has always been a big part of my life," Du said. "I'm super excited to make something that can actually help the world."

Du wants to go to the Massachusetts Institute of Technology to study marine-related science.

She and the other nine finalists will take part in the final competition in October at the 3M Innovation Center in Saint Paul.