POLLUTED DUST HURTS OCEAN LIFE
Researchers have found yet another worrisome trend impacting the health of the Pacific Ocean. Modeling shows that for decades, air pollution drifting from East Asia out over the world’s largest ocean has kicked off a chain reaction that contributed to oxygen levels falling in tropical waters thousands of miles away.
“There’s a growing awareness that oxygen levels in the ocean may be changing over time,” said Taka Ito, an associate professor in Georgia Tech’s School of Earth and Atmospheric Sciences (EAS). “One reason for that is the warming environment — warm water holds less gas. But in the tropical Pacific, the oxygen level has been falling at a much faster rate than the temperature change can explain.”
In the study, the researchers describe how air pollution from industrial activities has raised levels of iron and nitrogen — key nutrients for marine life — in the ocean off the coast of East Asia. Ocean currents then carry the nutrients to tropical regions, where they promote biological activity, eventually reducing subsurface oxygen.
That process plays out all across the Pacific, but the effects are most pronounced in tropical areas, where dissolved oxygen is already low. Athanasios Nenes, a professor in EAS and the School of Chemical and Biomolecular Engineering, said the research shows how far-reaching the impact of human industrial activity can be.
“The scientific community always thought that the impact of air pollution is felt in the vicinity of where it deposits,” Nenes said. “This study shows that the iron can circulate across the ocean and affect ecosystems thousands of kilometers away.”
The study, which was published in the journal Nature Geoscience, was sponsored by the National Science Foundation. — Josh Brown