Rivers carry plastic waste thousands of kilometres in just a few months © Sara Hylton/NGS

Sea spreads plastic waste thousands of kilometres from source in just months

‘Message in a bottle’ tags show how far and how fast plastic can move, scientists say.

Plastic pollution can travel “thousands of kilometres in just a few months”, scientists have said.

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Their findings, published in the journal Plos One, are based on data from GPS and satellite tags in 25 plastic bottles.

A tagged bottle at the sea © University of Exeter
A tagged bottle at the sea © University of Exeter

The researchers from the University of Exeter and the Zoological Society of London released three of the 500ml bottles directly into the Bay of Bengal to look at the path followed by litter once it reaches the sea. The team said that one of these bottles travelled the furthest of any in their study, at 2,845km in 94 days.

The rest of the bottles were placed at various sites along the river Ganges, which originates in the Himalayas and flows through India and Bangladesh and eventually empties into the Bay of Bengal in the north-eastern part of the Indian Ocean.

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“Our ‘message in a bottle’ tags show how far and how fast plastic pollution can move,” said lead author Dr Emily Duncan, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall. “It demonstrates that this is a truly global issue, as a piece of plastic dropped in a river or ocean could soon wash up on the other side of the world.”

The team found that bottles occasionally got stuck on their way downstream while moving in the Ganges. Bottles at sea covered far greater distances, following coastal currents at first but then dispersing more widely, the team said.

Bottle tags ready for release © Heather Koldewey
Bottle tags ready for release © Heather Koldewey

The scientists are hoping that their electronic bottle tags will be a “powerful tool” for education and raise awareness about the effects of plastic pollution. They estimate that rivers transport up to 80 per cent of the plastic pollution found in oceans.

“This could be used to teach about plastic pollution in schools, with children able to see where their bottle goes,” Dr Duncan said. “Data from these tags could feed into global models to give us a clearer picture of how plastic moves across the ocean and where it ends up.”

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The research was conducted as part of the National Geographic Society’s Sea to Source: Ganges expedition.

Reader Q&A: How does plastic get into the oceans?

Asked by: Tamsin Nicholson, via email

Around 80 per cent of the plastic waste found in the oceans today originated inland. Littering, poor waste management and industrial activity can all allow plastic to enter the natural environment.

A significant proportion of this then blows into rivers and streams, which carry it into the ocean. This is particularly common in countries where waste infrastructure is lacking: an estimated two billion people worldwide don’t have access to solid waste collection.

On top of this, wastewater from our homes often contains tiny pieces of plastic, including microbeads from cosmetics (now banned in the UK) and fibres from polyester clothing. Tackling plastic pollution therefore requires individuals, governments and companies across the globe to work together to reduce plastic consumption and waste.

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