DATE: May 1, 2020
SNIP: Scientists have identified the highest levels of microplastics ever recorded on the seafloor.
The contamination was found in sediments pulled from the bottom of the Mediterranean, near Italy.
The analysis, led by the University of Manchester, found up to 1.9 million plastic pieces per square metre.
These items likely included fibres from clothing and other synthetic textiles, and tiny fragments from larger objects that had broken down over time.
The researchers’ investigations lead them to believe that microplastics (smaller than 1mm) are being concentrated in specific locations on the ocean floor by powerful bottom currents.
“These currents build what are called drift deposits; think of underwater sand dunes,” explained Dr Ian Kane, who fronted the international team.
“They can be tens of kilometres long and hundreds of metres high. They are among the largest sediment accumulations on Earth. They’re made predominantly of very fine silt, so it’s intuitive to expect microplastics will be found within them,” he told BBC News.
It’s been calculated that something in the order of four to 12 million tonnes of plastic waste enter the oceans every year, mostly through rivers.
Media headlines have focussed on the great aggregations of debris that float in gyres or wash up with the tides on coastlines.
But this visible trash is thought to represent just 1% of the marine plastic budget. The exact whereabouts of the other 99% is unknown.
Some of it has almost certainly been consumed by sea creatures, but perhaps the much larger proportion has fragmented and simply sunk.