Man-made nanoparticles could help store excess carbon dioxide in the ocean

The urgent need to remove excess carbon dioxide from Earth’s environment could include enlisting some of our planet’s smallest inhabitants, according to an international research team led by Michael Hochella of the Department’s Pacific Northwest National Laboratory. of Energy.

Hochella and his colleagues looked at the scientific evidence for ocean seeding with iron-rich synthetic fertilizer particles near ocean plankton. The aim would be to feed phytoplankton, microscopic plants that are a key part of the ocean ecosystem, to promote growth and carbon dioxide (CO₂) uptake. The analytical article appears in the journal Nature nanotechnology.

“The idea is to augment existing processes,” said Hochella, a researcher at Pacific Northwest National Laboratory. “Humans have fertilized the land to grow crops for centuries. We can learn how to responsibly fertilize the oceans.”

In nature, nutrients from the earth reach the oceans through rivers and blow dust to fertilize plankton. The research team proposes to take this natural process a step further to help remove excess CO₂ across the ocean. They studied evidence suggesting that adding specific combinations of carefully designed materials could effectively fertilize the oceans, encouraging phytoplankton to act as a carbon sink.

Organisms would absorb carbon in large quantities. Then, as 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 running out,” Hochella said. “To fight against rising temperatures, we must reduce CO₂ levels globally. Looking at all of our options, including using the oceans as CO₂ sinking, gives us the best chance of cooling the planet.”

Learning from literature

In their analysis, the researchers claim that engineered nanoparticles offer several attractive attributes. They could be highly controlled and specifically tuned for different ocean environments. Surface coatings could help particles attach to plankton. Some particles also have light-absorbing properties, allowing plankton to consume and use more CO₂.

The general approach could also be adapted to meet the needs of specific ocean environments. For example, one region might benefit the most from iron-based particles, while silicon-based particles may be more effective elsewhere, they say.

The researchers’ analysis of 123 published studies showed that many non-toxic metal-oxygen materials can safely enhance plankton growth. The Earth’s stability, abundance and ease of creation make these materials viable options as plankton fertilizer, they say.

The team also analyzed the cost of creating and distributing the different particles. Although the process is considerably more expensive than adding non-technical materials, it would also be much more efficient.