SOURCE: The Guardian
DATE: May 12, 2020
SNIP: Hundreds of thousands of tonnes of mismanaged waste could be blowing ashore on the ocean breeze every year, according to scientists who have discovered microplastics in sea spray.
The study, by researchers at the University of Strathclyde and the Observatoire Midi-Pyrénées at the University of Toulouse, found tiny plastic fragments in sea spray, suggesting they are being ejected by the sea in bubbles. The findings, published in the journal Plos One, cast doubt on the assumption that once in the ocean, plastic stays put, as well as on the widespread belief in the restorative power of sea breeze.
Around 359m tons of plastic was manufactured globally in 2018, and some studies suggest as much as 10% of it ends up in the sea each year.
Steve Allen, a PhD candidate at Strathclyde who co-led the study, said: “Sea breeze has traditionally been considered ‘clean air’ but this study shows surprising amounts of microplastic particles being carried by it. It appears that some plastic particles could be leaving the sea and entering the atmosphere along with sea salt, bacteria, viruses and algae.”
The “bubble burst ejection” of particles in sea fog or spray, described by Allen as “like soda in a glass when it hits your nose”, is a well-known phenomenon. But the new study is the first time microplastics have been shown to be ejected from the ocean.
“We keep putting millions of tonnes of plastic into the ocean every year,” said Allen. “This research shows that it is not going to stay there forever. The ocean is giving it back to us.”
Plastic debris, such as plastic bags and bottles, breaks down into smaller microplastic in the sea, often invisible to the eye. The microplastics in the sea spray were between five micrometres and up to 140 micrometres long. The researchers estimated that up to 136,000 tons of microplastic could be blown on shore by sea spray every year.
The researchers captured water droplets from sea spray at Mimizan beach in Aquitaine, on the south-west Atlantic coast of France in the Bay of Biscay, using a “cloud catcher” and filters, set up on top of a sand dune. They analysed the water droplets for microplastics, sampling various wind directions and speeds, including a storm and sea fog. The sea fog generated by the surf produced the highest counts, of 19 plastic particles per cubic metre of air.