An underwater robot can autonomously scan large areas of seabed to identify plastic, rubber and metal rubbish using artificial intelligence image recognition. The technology will help focus the limited budgets for clean-up efforts on the most toxic and environmentally damaging materials.
Trygve Olav Fossum and his colleagues at the Norwegian firm Skarv Technologies created a 45-kilogram underwater robot equipped with stereo cameras, while researchers at Ecotone, another firm in Norway, produced a spectrometer that can identify the material an object is made of even through metres of murky water.
Plastic pollution could upset the ecology of lakes and rivers by leaching chemicals that cause bacteria to thrive, unbalancing the aquatic ecosystem.
Eleanor Sheridan at the University of Cambridge and her colleagues compared the impact of chemical compounds leached from cut-up shopping bags from various stores. The pieces of plastic were added to water samples taken from 29 Scandinavian lakes in 2019. The group found that bacteria exposed to the leachate from the bags multiplied on average at more than twice the rate of bacteria in control samples of distilled water.
If replicated in the wild, the boost in bacteria could stimulate the aquatic food web by providing food for other organisms. But Sheridan says that doesn’t mean plastic pollution is good news for fish populations at the top of the web. “Yes, you’re going to benefit some species of bacteria, but you’re almost certainly going to throw off the whole balance of species in the ecosystem. And that’s not a good thing at all,” she says.
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The team based the plastic leachate levels on concentrations found in a study of Swiss lakes, but the amount added in the experiment may have been a sweet spot that aids growth. Other studies have shown that higher concentrations can be toxic to bacteria. “So we might have hit this kind of low threshold that’s able to benefit growth,” says Sheridan.
The study comes with a few caveats. Although lakes of a wide range of sizes were tested, all were from Scandinavia. The team also didn’t test different concentrations of the leachate and only tried with low-density polyethylene (LDPE) rather than other plastic leachate too.
However, LDPE from bags is the biggest pollutant of water bodies. People should be aware of the unintended consequences of plastic waste and stop it from getting into the wider environment, says Sheridan. “We’re much more focused on the kind of macro level, and it’s important for people to also be aware that there can be this much smaller scale chemical effect on species in an ecosystem,”Plastic pollution is ubiquitous and growing, but knowing the best way to stop it has largely been a guessing game so far. Now, a study has found that if the world undertook every feasible action to cut plastic pollution, we would still only manage to get rid of 78 per cent of it by 2040, compared with a business-as-usual scenario.
This momentous effort would still leave us with an extra 710 million metric tonnes of pollution. Does that make the whole thing hopeless?
No, says Richard Bailey at the University of Oxford, who worked on the study. While a complete ban on plastics is unrealistic, there is still much we can do, he says. “The idea we would sit by and do nothing as this problem doubles on an annual basis – just imagine how much that means cumulatively in the ocean.
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