Mangrove forests act as sinks for plastic waste

“Conserving mangrove forests is key to avoiding the resuspension of buried plastic into the water column where they could affect marine organisms,” says the study’s lead author, Cecilia Martin, a marine scientist from King Abdullah University of Science and Technology, Saudi Arabia.

Mangrove plant aerial roots and branches trap plastic items brought in by ocean currents, where they fragment into less buoyant, smaller particles. Microorganisms colonising the particles make them heavier, rapidly sinking them, where they eventually deposit in the sediment.

The scientists had analysed plastic pieces extracted from dated mangrove sediments and found small fragments and films that probably came from bottles, food wraps and ropes. They also found that plastic concentration decreased from the surface to the deeper layers of the sediments. 

They conclude that plastic burial rates in marine sediment have risen exponentially since the 1950s, at a rate of 8.5 per cent each year, in line with the rise in global plastic production. The researchers predict burial rates will rise to 7 to 20 times higher than the present rates by 2050.

Sign-up to receive our e-alert update every two weeks to keep up with everything new on the portal.