Seeding the oceans with fertilizer at the nanometer scale could create a substantial and much-needed carbon sink. Credit: Illustration by Stephanie King Pacific Northwest National Laboratory
Iron-based fertilizer in the form of nanoparticles has the potential to store excess carbon dioxide in the ocean.
An international team of researchers led by Michael Hochella of the Pacific Northwest National Laboratory suggests that the use of tiny organisms could be a solution to address the pressing need to remove excess carbon dioxide from Earth’s environment.
The team conducted an analysis, published in the journal nature nanotechnologyabout the possibility of seeding the oceans with iron-rich engineered fertilizer particles near ocean plankton, microscopic plants crucial in the ocean ecosystem, to fuel phytoplankton growth and carbon dioxide uptake.
“The idea is to augment existing processes,” said Hochella, a lab member at Pacific Northwest National Laboratory. “Humans have fertilized the land for farming for centuries. We can learn to fertilize the oceans responsibly.”
Michael Hochella is an internationally recognized environmental geochemist. Credit: Virginia Tech Photo Services
In nature, nutrients from the land reach the oceans through rivers and blown 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 studied evidence suggesting that adding specific combinations of carefully engineered materials could effectively fertilize the oceans, encouraging phytoplankton to act as a carbon sink. Organisms would absorb carbon in large quantities. Then, when they die, 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 lower CO2 levels on a global scale. Examining all of our options, including using the oceans as CO2 sinks, gives us the best chance of cooling the planet.”
Drawing ideas from the literature
In their analysis, the researchers argue that engineered nanoparticles offer several attractive attributes. They could be highly controlled and tuned specifically for different ocean environments. Surface coatings could help particles stick to plankton. Some particles also have light-absorbing properties, allowing plankton to consume and use more CO2. The general approach could also be adjusted to meet the needs of specific ocean environments. For example, one region might benefit more from iron-based particles, while silicon-based particles may be more effective elsewhere, they say.
The researchers’ analysis of 123 published studies showed that numerous non-toxic metallic oxygen materials could safely enhance plankton growth. The stability, abundance on Earth, and ease of creation of these materials make them viable options as plankton fertilizers, they argue.
The team also looked at the cost of creating and distributing different particles. While the process would be substantially more expensive than adding non-engineered materials, it would also be significantly more effective.
Reference: “Potential Use of Engineered Nanoparticles in Ocean Fertilization for Large-Scale Atmospheric Carbon Dioxide Removal” by Peyman Babakhani, Tanapon Phenrat, Mohammed Baalousha, Kullapa Soratana, Caroline L. Peacock, Benjamin S. Twining, and Michael F. Hochella Jr., November 28, 2022, nature nanotechnology.
DOI: 10.1038/s41565-022-01226-w
In addition to Hochella, the team included researchers from England, Thailand and several US-based research institutions. The study was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation programme.
