For a long time, scientists believed that the ocean releases microplastic into the atmosphere. However, a new study from the Max Planck Institute for Meteorology (MPI-M) has revealed the opposite—the ocean acts as a sink for microplastic rather than a source.
How Did This Misconception Arise?
Previously, researchers assumed that microplastic could be released from the ocean into the air through several processes:
Breakdown of plastic wasteLarge plastic objects in the water break down due to sunlight, waves, and salt, turning into microplastic.It was thought that these particles could enter the atmosphere through sea spray and aerosols from waves.
Biological processesSome marine bacteria decompose plastic, and marine organisms may process it and release it back into the environment.
Melting sea iceArctic ice has accumulated large amounts of microplastic, leading to the assumption that as it melts, microplastic enters the ocean and air.
What Did the New Study Reveal?
Using a global chemical transport model, scientists discovered that:
Around 15 percent of airborne microplastic settles in the ocean.
Larger particles sink quickly, while smaller ones can remain in the air for up to a year, traveling across the globe.
The ocean does not release microplastic back into the air but instead acts as a massive filter, capturing it from the atmosphere.
What Does This Mean for Fighting Pollution?
Now it is clear that the main source of microplastic is not the ocean, but land-based activities.
Cars, factories, waste incineration, and urban dust release microplastic into the atmosphere, which is then carried by winds worldwide.
Oceans, forests, and polar regions accumulate this pollution but do not generate it.
This discovery shifts the focus of pollution control—reducing microplastic emissions on land is crucial to preventing its spread into air, water, and ecosystems worldwide.