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Microplastics May Be Turning Great Pacific Garbage Patch Cyan
· Confirmed
In Short: New research suggests microplastics in the Great Pacific Garbage Patch could be altering the ocean's color, turning it cyan.
The Great Pacific Garbage Patch, located roughly midway between Hawaii and California, is undergoing a color change that may be linked to microplastics, according to a study published in the journal Communications Earth & Environment. The patch, which covers around 1.6 million square kilometers and contains nearly 80,000 tonnes of plastic debris, is thought to be brightening in both blue and green wavelengths, creating a cyan hue.
Researchers from the University of Bergen in Norway, including Shea Cheatham, Daniel Koestner, and Børge Hamre, analyzed satellite data spanning from 2002 to 2022 and found a subtle but statistically significant brightening of the ocean near the garbage patch. This brightening is particularly noticeable in blue and green wavelengths, which together create the color cyan.
The study suggests that microplastics, which can reach densities of up to 17 milligrams per cubic liter near the surface of the ocean in parts of the garbage patch, may be responsible for this color change. Microplastics are known to scatter light differently than natural ocean components, potentially producing unique optical signatures detectable from space.
Cheatham and his team conducted lab experiments to understand how microplastics might influence the ocean's color. They found that when microplastics were included in their simulations, the pattern of brightening in both blue and green light near the Great Pacific Garbage Patch became more than four times as likely. However, the researchers emphasize that further verification is needed to confirm that microplastics are directly causing the observed color shift.
The Great Pacific Garbage Patch is estimated to contain about 1.8 trillion plastic pieces, with microplastics accounting for 94 percent of the pieces but only 8 percent of the overall mass. Larger plastics, such as fishing nets and ropes, make up 47 percent of the plastic mass in the patch, equivalent to the mass of more than 6,500 school buses.
The unique circulation patterns that have created the garbage patch have also made it more likely to experience the kind of microplastic accumulation needed to be detectable from space. While most concern about the vast patch has focused on its impact on sea life and environmental health, the new findings suggest that the patch may also be altering the ocean's color.
The researchers note that the color change observed in satellite data does not definitively prove that microplastics are the cause, but it is a compelling indication. They plan to conduct further studies to verify their findings by directly sampling the waters of the Great Pacific Garbage Patch.
What this adds
The study adds to the growing body of research on the environmental impacts of plastic pollution, particularly in the Great Pacific Garbage Patch. It suggests that microplastics may be altering the ocean's color, but further verification is needed to confirm this link.
What's confirmed
- The concentration of microplastics in the garbage patch may have become high enough to change the color of the ocean in which they drift, according to a new study by ocean optics specialists Shea Cheatham, Daniel Koestner, and Børge Hamre of the University of Bergen in Norway.
What's still developing
- “In short, this is compelling evidence for a potential satellite signature of microplastic accumulation, rather than evidence that satellites have actually detected the microplastics themselves,” says Smyth.
- "What's interesting about the optical signature of microplastics is that they generally do not absorb much light at all across the visible spectrum, and are strong scatterers," Cheatham said.
- Vast amounts of discarded plastic accumulate in the oceans, sometimes forming enormous garbage patches that threaten marine life.
- Instead of disappearing, these materials gradually fragment into increasingly smaller particles, including microplastics and nanoplastics.