Tagged bottles reveal the path of plastic through the ocean
The more we know about the problem of plastic pollution, the better we’ll be able to intervene and clean up, or even prevent, the mess. That includes understanding the way it moves through the marine environment, and a new study has shed further light on this process through the use of tagged plastic bottles. The bottles were dropped in the Ganges river and some ended up thousands of kilometers away.
While the plastic building up in the ocean gets a lot of the attention, studies have shown that millions of metric tons of it actually comes via the world’s river systems. As part of National Geographic's Source to Sea project, scientists at the University of Exeter set trace this path through the waterways and into the ocean, by tagging plastic bottles much like biologists might tag wildlife.
GPS and satellite tags were placed in 25 500-ml (17-oz) bottles, with their buoyancy and shape designed to emulate the movement of regular plastic bottles. These were then released into the Ganges river and the Bay of Bengal, with the researchers using these plastic litter tags to gain an idea of how a discarded plastic bottle might move through the environment.
The tagged bottles were successfully tracked through the Ganges river system and the Bay of Bengal that it feeds into, and far beyond. Some occasionally got stuck on their way downstream, while the bottles at sea were found to cover larger distances with the help of ocean currents. The maximum distance that one of the tagged bottles was found to have traveled was 2,845 km (1,770 mi) in 94 days.
"Our 'message in a bottle' tags show how far and how fast plastic pollution can move," says lead author Dr Emily Duncan. "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 scientists hope this approach can become an educational tool to raise awareness about plastic waste, both in schools and for scientists working to tackle the environmental issue.
"This could be used to teach about plastic pollution in schools, with children able to see where their bottle goes,” says Duncan. ”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."
The research was published in the journal PLOS One.
Source: University of Exeter