Plastic Never Really Goes Away: How Marine Debris Breaks Down

Most of what we throw away does not disappear in the ocean — it just gets smaller. Products made by people are not completely biodegradable. They can take a long time, possibly hundreds of years, to break down, and some never do: glass does not degrade at all.

Marine debris. How long it lasts depends on what it is made of, its size, its thickness and where it ends up. Credit: NOAA.

What decides how long it lasts

How long a piece of debris takes to degrade depends on several things:

• what it is made of
• its size and thickness
• its surroundings — for example, how much sunlight it gets, and whether it sits on a beach or floats at sea

The problem with "photodegradable" plastic

Some plastics are photodegradable, meaning light can break them down. But breaking down is not the same as disappearing. These plastics can come apart from the form they were made in, yet they never completely degrade. Instead they divide into tiny pieces called microplastics.

Microplastics

Microplastics are the multicolored bits of plastic that turn up in a handful of beach sand or in the ocean. Scientists are still investigating what they do to the ocean and the animals that live in it.

Sources

Based on "Can marine debris degrade on its own in the environment?" from NOAA's National Ocean Service, a work of the United States government in the public domain.