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+--- Thread: Research Parts of ocean turning weird shade of blue-green. Scientists suspect it's plastic (/thread-21807.html)
Parts of ocean turning weird shade of blue-green. Scientists suspect it's plastic - C C - Nov 9, 2026
https://www.zmescience.com/science/news-science/pacific-garbage-patch-ocean-color-microplastics/
EXCERPTS: Something strange is happening to the Pacific Ocean. Near the Great Pacific Garbage Patch, the water has been reflecting more blue and green light over the past two decades.
[...] Despite its name, the Great Pacific Garbage Patch isn’t a floating island of trash. It’s an enormous accumulation zone between Hawaii and California, where circulating ocean currents concentrate discarded fishing gear, bottles, fragments, and countless microscopic particles.
A landmark 2018 study estimated that the patch contained around 1.8 trillion pieces of plastic spread across 1.6 million square kilometers (around 1 million square miles). Microplastics accounted for approximately 94% of those pieces, although larger debris made up most of the mass. Much of this pollution is almost impossible to see directly.
[...] Using satellites to hunt for ocean plastic isn’t entirely new. In 2021, scientists used NASA satellite measurements of ocean surface roughness to estimate where microplastics might be accumulating. But the new study takes a different approach. Instead of looking for changes in the waves, researchers examined the light reflected by the water itself.
The idea builds on earlier laboratory experiments showing that tiny plastic particles scatter blue-green light in distinctive ways. Now, for the first time in this line of research, they’ve identified a matching pattern in decades of satellite observations near the Great Pacific Garbage Patch.
The ocean looks blue largely because water absorbs longer wavelengths of visible light more strongly than shorter blue wavelengths. But its appearance also depends on everything suspended or dissolved within it.
Phytoplankton, for example, absorb light for photosynthesis, influencing the ocean’s green and blue tones. Dissolved organic matter and other particles also affect which wavelengths escape back toward the sky. Microplastics behave differently.
Many tiny plastic particles absorb relatively little visible light but scatter it efficiently, sending some of the incoming sunlight back toward the surface. Earlier laboratory experiments found that this scattering can be especially pronounced around 490 nanometers, near the boundary between blue and green light.
That gave the researchers a testable idea. If concentrations of suspended microplastics were increasing, the ocean might become brighter at particular wavelengths, producing a distinctive pattern that satellite instruments could detect. The blue-green brightening they found near the garbage patch was consistent with that prediction. But consistency isn’t proof. Natural changes in the ocean can also alter its color, so the team needed to investigate other possible explanations... (MORE - missing details)
PAPER: https://www.nature.com/articles/s43247-026-04071-0