Someone who lives on the Ganges in India recently received a gift that we can safely say has never been given to anyone on earth. At first it must have looked like an ordinary plastic bottle floating down the river, except for the rod sticking out of its tip, like a sailboat with a mast but no sail. The fifteen who remain anonymous must have become curious and tore open the 500-milliliter bottle when they discovered that it was indeed filled with electronics. This included a SIM card that the person placed on a mobile device and then logged into Facebook.
"The reason we knew it was being used was when we got the bill," says Alasdair Davies, a technical specialist at the Zoological Society of London. You see, Davies, along with nature conservation scientist Emily Duncan of the University of Exeter and other researchers, had not long before released the bottle and nine others into the Ganges as part of a clever experiment to show how plastic pollution was released by rivers and eventually after outside moved to the sea. Using SIM cards, the ill-fated bottle and its companions were able to connect to cell towers every three hours as they headed down the river. It was recorded in detail how far and how fast the devices drove. One sailed 380 miles over 51 days.
But that particular bottle had become a villain. The researchers had planned not to use more than 100 megabytes of data on the SIM card, since each upload to a cell tower only took a maximum of 2 kilobytes. This card had managed to collect 300 megabytes of data. "We said," How the hell did our bottle use 300 megabytes of data? "Davies recalls. So they looked at the location logs and watched the bottle jump out of the river and land in a house – not typical behavior for an inanimate object." Then it went offline, and then the data was gathered ", he says.
While some of the bottles traveled many kilometers over many weeks, others lost their ability to convey their location. Still others appear to be caught in fishing nets. However, this is not a waste of an electronic research bottle – on the contrary. "It provides realistic data about what happens to plastic," says Duncan, lead author of a new paper in PLOS ONE, describing the system. “Some could be taken out of the river, others could get caught in fishing gear out there. So our mishaps also give us a realistic idea of what is happening. "
Duncan and Davies actually cobbled together two generations of electronic bottles. Their first generation of devices, which sailed along the aisle, had many cell towers that they could ping on along the way, so a SIM card would be sufficient. But the researchers also wanted to see how plastic bottles might behave when they reach the ocean. So they equipped a second generation with GPS. Here they took inspiration from their previous work on tracking sea turtles: GPS works great on the open sea, far away from cellular services. (Their designs are open source so any plastics researcher can develop their own and even improve the system.)
For both versions of the device, they had to find out how a tube filled with electronics behaves like a real piece of plastic waste. "It's really just about the center of gravity," says Davies. For example, you couldn't load all of the batteries on one side of the bottle. They also left an open cavity in the bottle so that the trapped air would give it buoyancy and keep about half of the device above the waterline and half below the waterline. Critically, the bottle had to align itself so that its antenna pointed towards the sky and not towards the river floor.
"We played a lot in buckets in our gardens, swam the bottles, tested configurations and found exactly the right thing," says Davies. “The right wall thickness – everything right – until we get something that imitates a bottle. So we threw another bottle next to it and they would be floating in the same orientation. "
The team was convinced of the seaworthiness of the GPS versions of the bottles and used them in Bangladesh, near the mouth of the Ganges and also in the Bay of Bengal. The researchers then watched the devices roll around the Bay of Bengal on similar trails. A bottle traveled nearly 1,800 miles in 94 days. They tended to head west towards the east coast of India and were eventually caught up in powerful vortex systems. "We see a kind of spiral on the map," says Duncan. "That is an indication of where we might find clumps of plastic."
University of Exeter
And that's why plastic bottles must be carefully constructed to withstand strenuous journeys along the Ganges and across the Bay of Bengal: it shows where garbage accumulates in these waters. Previously, scientists had developed models based on variables such as ocean currents, winds, and coastal shapes to show how pieces of plastic can move around. These models indicate that rubbish tends to stick to the coast, wash out a little, and then wash in again and again. The results of this new work provide strong real-world evidence to underpin this dynamic: the electronic bottles tended to hug the coast and travel hundreds of miles in parallel, rather than immediately washing far out to sea.
"Oceanographic models can provide valuable insights into how plastics are likely to move in the ocean," said Nicholas Mallos, senior director of the Trash Free Seas program at Ocean Conservancy, who was not involved in the new research. "However, using real-time plastic tracking tools can help us uncover things that may have been previously unknown." For example, where could plastic get caught in sinks in the open ocean? Could critical living spaces be disproportionately threatened by the accumulation of plastic?
"Where's the missing plastic?"
“In general, one of the biggest gaps is figuring out how far plastics move in the environment,” adds Mallos. "In fact, many researchers will even ask: Where is the missing plastic? Because we've quantified how much is likely to go into the ocean, but we haven't yet been able to fully quantify where all that plastic ends up just across the ocean."
The data gathered from these electronic bottles could shed light on how humanity is coping with the plastic crisis in the ocean. In 2018, a group called The Ocean Cleanup deployed a 600-meter-long U-shaped catcher in the Great Pacific Garbage Patch, which is known to accumulate plastic waste. Oceanographers immediately pondered whether the catcher would inevitably break in two (yes, it did), and because it distracts from more preventative solutions. This would combat pollution further upstream and prevent it from even reaching the ocean. To this end, Baltimore Harbor has deployed two "interceptors," affectionately known as the Mr. Trash Wheel and Professor Trash Wheel, to gobble up floating plastic before it can reach the Atlantic and stack in barges for disposal. It's such a good idea that The Ocean Cleanup created its own version for use at the mouths of the world's rivers.
As these new electronic bottles clearly show, plastic can float hundreds of kilometers and perhaps more downstream in rivers. This kind of resilience shows that pollution is aiming to eventually reach the ocean. Plus, you have another problem: there are hundreds of kilometers of riverbanks along which new litter can get into the system. In other words, it's not just coastal cities loading rivers with plastic bottles making a journey of perhaps a few miles to the sea, but cities up and down the river.
Bottles are only part of the problem – a galaxy of other plastic products such as containers and packaging end up in rivers and the ocean. How could they all act when on the water? Duncan and her colleagues may one day tweak their technology to find the answer by putting trackers in even smaller pieces of trash. "Because technology moves so quickly and everything is getting smaller and lighter so easily, it would be really interesting to end up with something that you can just stick on the crispy packet or a plastic bag," says Duncan. "Something that is much lighter, has no bearing on how it moves, and that is also able to track those parts."
And because this project is open source, researchers all over the world can build their own sensor-packaged plastics. So the next time you're walking along a river and complaining about the passing pollution, you should be aware that these pieces of trash may actually be scientific spies.
This story originally appeared on wired.com.