What is ‘marine snow’? And how do microplastics slow the rate at which carbon is pulled from the sea surface to the depths?

It turns out plastics in the ocean do more than suffocate turtles, fish and other marine life.

A new study co-authored by Northeastern researcher Aron Stubbins shows that microplastics may reduce the ability of the ocean to help offset the climate crisis by slowing down the rate at which carbon is taken from the sea surface to the depths.

For millennia, the ocean has been part of a carbon sink process in which dead phytoplankton clump together and fall into the deep ocean in showers of what look like “marine snow,” says Stubbins, a professor of marine and environmental science.

The resulting carbon sequestration is a marine version of how trees and plants on terrestrial Earth take carbon from the atmosphere and store it in soil, he says.

But research by Northeastern shows that microplastics in the ocean are slowing the process down by making the “marine snow” more buoyant, Stubbins says.

“Plastics want to float. If phytoplanktons grow on microplastics in biofilms, instead of as free living organisms, that changes the buoyancy of the phytoplankton when they die,” Stubbins says.

“Basically, the plastics are slowing down the sinking rate of the marine snow, which is potentially reducing the efficiency with which the ocean can remove carbon dioxide from the atmosphere,” he says.

Read more from Northeastern Global News

Photo by Matthew Modoono/Northeastern University

Chemistry and Chemical Biology
Marine and Environmental Sciences