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A solution for excess CO2? New study suggests fertilizing the ocean

Fertilizing the Ocean to Store Carbon Dioxide
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Fertilizing the ocean to store carbon dioxide

Seeding the oceans with nanoscale fertilizers could create a much-needed, significant carbon sink. Photo credit: Illustration by Stephanie King | National Laboratory of the Pacific Northwest

Iron-based fertilizer in the form of nanoparticles has the potential to store excess carbon dioxide in the ocean.

An international research team led by Michael Hochella from the National Laboratory of the Pacific Northwest suggests that using tiny organisms could be a solution to address the urgent need to remove excess carbon dioxide from the Earth’s environment.

The team conducted an analysis that was published in the journal nature nanotechnologyon the possibility of seeding the oceans with iron-rich artificial fertilizer particles in the vicinity of marine plankton, important microscopic plants in the marine ecosystem, to promote phytoplankton growth and carbon dioxide uptake.

“The idea is to expand on existing processes,” said Hochella, a lab worker at Pacific Northwest National Laboratory. “Man has fertilized the land for centuries to grow crops. We can learn to fertilize the oceans responsibly.”

Michael Hochella

Michael Hochella is an internationally recognized environmental geochemist. Photo credit: Virginia Tech Photographic Services

In nature, nutrients from land enter the oceans through rivers and dust to fertilize plankton. The research team proposes to take this natural process a step further to help remove excess CO2 through the ocean. They examined evidence that suggests adding specific combinations of carefully engineered materials could effectively fertilize the oceans and encourage phytoplankton to act as a carbon sink. The organisms would absorb carbon in large quantities. Then when they died, they would sink deep into the ocean, taking the excess carbon with them. Scientists say this proposed fertilization would simply speed up a natural process that already safely sequesters carbon in a form that could remove it from the atmosphere for thousands of years.

“At this point, time is of the essence,” Hochella said. “To combat rising temperatures, we must reduce CO2 levels worldwide. If we consider all of our options, including using the oceans as a carbon sink, we have the best chance of cooling the planet.”

draw conclusions from the literature

In their analysis, the researchers argue that engineered nanoparticles offer several attractive properties. They could be highly controlled and specially tuned for different ocean environments. Surface coatings could help the particles attach to plankton. Some particles also have light-absorbing properties, allowing plankton to consume and utilize more CO2. The general approach could also be tuned to meet the needs of specific ocean environments. For example, one region might benefit most from iron-based particles, while silicon-based particles might be most effective elsewhere, they say.

The researchers’ analysis of 123 published studies showed that numerous non-toxic metal-oxygen materials could safely promote plankton growth. The stability, abundance on Earth, and ease of manufacture of these materials make them viable options as plankton fertilizers, they argue.

The team also analyzed the cost of creating and distributing different particles. While the process would be significantly more expensive than adding non-engineered materials, it would also be significantly more effective.

References: “Potential use of engineered nanoparticles in ocean fertilization for large-scale climate carbondioxid Removal” by Peyman Babakhani, Tanapon Phenrat, Mohammed Baalousha, Kullapa Soratana, Caroline L. Peacock, Benjamin S. Twining and Michael F. Hochella Jr., 28 November 2022, nature nanotechnology.
DOI: 10.1038/s41565-022-01226-w

In addition to Hochella, the team included researchers from England, Thailand and several US research institutions. The study was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation programme.

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