Plastic, now ubiquitous in the modern world, is becoming a growing threat to human health and the environment. Evidence of plastic pollution extends all over the world, from grocery bags reaching the deep sea to microplastics that enter human bloodstreams and even into plant pots.
In the search for solutions to tackle the increase in plastic waste, scientists at the University of California, San Diego have developed new biodegradable materials designed to replace traditionally used plastic.
An interdisciplinary team of scientists led by Stephen Mayfield, a biologist at the University of California, San Diego, has demonstrated that polyurethane foams biodegrade in seawater. The results of the study were published in the journal Science of the Total Environment on September 22.
The problem of plastic pollution
According to a press release published on the Eurek Alert website, researchers are working to tackle the problem of plastic pollution, which is now being described as a global environmental crisis. In 2010, researchers estimated that 8 billion kilograms of plastic enter the ocean in one year, with a sharp escalation expected by 2025.
Upon entering the ocean, plastic waste disrupts marine ecosystems, migrating to central locations and forming garbage eddies like the Pacific Garbage Patch, which covers an area of more than 1.6 million square kilometres.
These plastics never degrade, but break down into smaller particles, eventually becoming microplastics that remain in the environment for a few centuries.
A unique opportunity to test materials in a natural ecosystem
Working with study co-author Samantha Clements, a marine biologist at the Scripps Institution of Oceanography, UCSD researchers conducted a series of tests of biodegradable polyurethane (currently used as foams in The first commercially available biodegradable shoes) at the Ellen Browning Scripps Memorial Pier and Experimental Aquarium.
The dock site provided scientists with a unique opportunity to test materials in the natural near-shore ecosystem, the microenvironment most likely to be vulnerable to plastic waste residue.
The study data indicates that microorganisms, a mixture of bacteria and fungi, live throughout the natural marine environment. The team found that polyurethane foam biodegrades into primary chemicals that microorganisms consume as nutrients in the ocean environment.
Plastic that gets dumped into the ocean turns into microplastics, and it has become a massive environmental problem, says Mayfield, a professor in the School of Biological Sciences and director of the California Center for Algae Biotechnology.
He added, "We have proven that it is possible to make high-performance plastic products that can also degrade in the ocean. The original plastic is not thrown into the oceans, but if this happens, this material becomes food for microorganisms instead of turning into garbage and microplastic particles that harm aquatic life."
Shoes make up a large proportion of the plastic waste that ends up in the world's oceans and landfills.
Decomposition test
To fully test the decomposition of polyurethane materials, which have been developed at UCLA over the past eight years, experts in biology, synthetic polymer chemistry and marine science joined the study. The foam samples were subjected to tidal and wave dynamics while tracking their molecular and physical changes using analysis. Infrared spectroscopy, as examined by electron microscope.
The results showed that these substances began to degrade in less than 4 weeks. The researchers then identified microorganisms from 6 marine sites around San Diego that were able to break down and consume polyurethane.
"There is no single system that can address these global environmental problems, but we have developed an integrated solution that works on land, and now we also know biodegradation in the ocean," Mayfield says.
"I was surprised to see the number of organisms that colonize these foams in the ocean, creating a microbial coral reef-like environment," he continued.
Tags:
SCIENCE UPDATE