New plastics are biodegradable in both oceans and drylands

Plastic pollution, including the widespread inundation of ecosystems and organisms with microplastics, is a major and growing concern. Researchers at the University of California, San Diego plan to counteract it with new biodegradable materials.

Image credits Natasha R. Gunawan et al. , (2022), college ecology.

The earth is full of plastic. From grocery bags choking marine animals to microplastics that permeate our food and water, they are a major environmental and health concern. Unfortunately, given our strong dependence on such materials, it is doubtful plastic away from the environment anytime soon.

Since we can’t wean ourselves off from this substance, researchers hope that a workable alternative could allow us to continue meeting our needs while also protecting the world around us. One solution proposed by a team of scientists at the University of California, San Diego, is a form of polyurethane plastic that can degrade naturally in seawater.

Solve the problem

“Improper disposal of plastic in the ocean turns into microplastics and becomes a massive environmental problem,” said Stephen Mayfield, a professor in the School of Biological Sciences and director of the California Center for Algae Biotechnology and corresponding author of the research paper.

“We have shown that it is entirely possible to make high-performance plastic products that can also degrade in the ocean. The plastic shouldn’t go into the ocean in the first place, but if it does, that substance becomes food for microorganisms and not plastic trash and microplastics that harm aquatic life.”

Millions of tons of plastic waste ends up in the ocean every year, causing massive disruption to marine ecosystems. They also accumulate in ocean eddies and form veritable plastic islands. The Great Pacific Garbage Patch is an excellent example of this island, covering an area of ​​more than 1.6 million square kilometers. Because the plastics we use today are not biodegradable, these trash stains can last for centuries, slowly disintegrating into tiny, harmful pieces – Microplastics.

The team previously showed that the polyurethane foam they developed can biodegrade in ground compost, showing its potential to reduce plastic pollution on dry land. Now, they’ve filled in these findings by showing that it can also be degraded naturally in seawater.

For the study, the team ran a series of tests on polyurethane materials they had previously developed; This material is currently used as a foam in the first commercially available product biodegradable shoesThe team explains. The experiments were conducted at the Ellen Browning Scripps Memorial Pier and Scripps Experimental Aquarium, giving the team the opportunity to test the materials in a natural ecosystem near the shore. Since this is the exact environment in which plastic waste enters the ocean, seeing how the material behaves here can teach us a lot about how it behaves in real use.

Foam samples of near-shore marine ecosystems were exposed and traced to molecular and physical changes using infrared spectroscopy and electron microscopy. This revealed that the samples began to degrade in less than four weeks after the initial exposure.

They report that once introduced into the wild, a group of marine organisms colonize the polyurethane foam and begin to break it down. Ultimately, this causes the substance to decompose into essential chemicals, which are then used as nutrients by these colonies of microorganisms. The team then bred the microorganisms living inside these samples to determine which species were able to degrade the material. They report finding a mixture of bacteria and fungi, which are widespread throughout natural marine environments, suggesting that the foam would behave similarly around the world.

“There is no single system that can address these global environmental problems, but we have developed an integrated solution that works on the ground – and we now know [it] It also biodegrades in the ocean,” Mayfield says. “I was surprised to see how many organisms colonize these foams in the ocean. It becomes something like a microbial coral.”

The team explains that shoes make up a large proportion of the plastic waste that ends up in the oceans and landfills – especially slippers, the world’s most popular footwear. That is why their material was first used in the manufacture of shoes. Current results show that such slippers can degrade in water as well as in landfill, bringing us one step closer to cleaning the Earth of plastic waste.

“Biodegradation of Renewable Polyurethane Foams in Marine Environments Through Depolymerization by Marine Microorganisms” has been studied published in the magazine college ecology.