Take a walk along the main beach and it won’t take long before you come across discarded trash. Old water bottles, garbage bags, straws, and countless other plastic scraps litter beaches around the world, eventually ending up in the ocean where they decompose over time. for decades or even centuries. International coastal cleanup and marine protection activities estimate In 2021, volunteers from 97 countries identified and removed approximately 4,000 tons of trash from beaches around the world. In most cases, finding all this junk still requires the naked eye and a fair amount of walking. But that may one day change, thanks to new satellite imaging technology developed by researchers at Australia’s RMIT University.
A research team has developed a new tool to highlight the unique spectral features of plastics. Armed with that knowledge, researchers can now accurately identify plastic items on beaches and distinguish them from sand, water, and plants. The researchers plan to publish their findings in a journal. next issue of magazine Marine pollution bulletincoastal cleanup organizations hope this new tool could be used to accelerate plastic removal efforts on beaches and potentially reduce the amount of harmful plastic that seeps into the ocean.
“This is very interesting because until now we have not had tools to detect plastic in coastal environments from space,” study co-author Mariela Sotobelerov said in a statement.
Plastic waste is not just an ocean problem
Satellite imagery has been used for years to help scientists identify floating plastic in the ocean and in giant garbage patches like the Great Pacific Garbage Patch. While this process works relatively well at identifying large chunks of plastic in the water, it is much less effective at finding plastic on the beach. Plastic on beaches often dissolves into the sand or is partially buried in the sand, making it very difficult to find. And while littering the ocean with plastic usually gets more attention, trash on beaches can also have a serious negative impact on local wildlife.
“Plastic can be mistaken for food, large animals can become entangled, and small animals like hermit crabs can become trapped inside things like plastic containers,” said study lead author Jenna Guffog. said in a statement.
These harmful effects are not limited to coastal living. If plastic is not removed, it is often sucked into the ocean, where it slowly breaks down into smaller microplastics and nanoplastics. These small plastics are consumed by fish and move up the food chain. Some researchers believe this cycle may even be contributing to the increase in microplastics found in humans, which researchers say could lead to endocrine disruption and poor reproductive health. I am concerned that there is. The full extent of the effects of microplastics on human health is not yet fully understood.
Plastic found in sandbag
That’s where new plastic detection systems come in. RMIT has created a new ‘spectral index’ that looks for patterns in reflected light emitted by plastics. Plastics, in particular, have special properties in the shortwave infrared (SWIR) electromagnetic spectrum that are not present in sand and other organic debris. The index they created, called the Coastal Plastic Debris Index (BPDI), essentially works like a filter that can be applied to satellite images of beaches. In this case those images were captured as follows: Worldview 3– A satellite located at an altitude of 617 kilometers above the Earth’s surface.
To test the new tool, the researchers went to a recycling facility and collected different types of plastic trash that might be found on beaches. Many of the objects were large pieces of trash. Some of the pieces have faded due to exposure to ultraviolet light, and this can happen to trash lying on beaches as well. They eventually settled on 14 different plastic targets, each approximately 2 square meters in size. They were placed 3.7 meters apart from each other on a beach in Victoria, Australia.
Once the plastic was in place, the satellite flew high above and took a series of photos. The researchers applied the index to the images and compared it with three other indexes already developed for plastic detection: two for plastic on land and one for objects floating in the ocean. The BPDI index significantly outperformed the other three indices in terms of accuracy. The other three typically had trouble identifying the plastic, sometimes even mistaking the shadow for trash. Still, the BPDI index wasn’t perfect. In particular, they had trouble identifying translucent polymers like plastic water bottles and bags, the study said.
Looking to the future, researchers hope to transfer these findings from limited testing environments to the real world. That might mean partnering with other organizations that specialize in cleaning up plastic from beaches and using their satellite imaging technology. Time is of the essence. recent Research suggests the amount of plastic entering the ocean It’s not slowing down and may be growing at a rate of 4% per year.
“We are considering partnering with organizations on the next steps of this research,” Sotobelerov said. “This is an opportunity to protect our delicate beaches from plastic waste.”
