A solution to excess CO2? New Study Suggests Ocean Fertilization

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

Planting nano-scale fertilizers in the oceans could create a much-needed, significant carbon sink. Credit: Illustration by Stephanie King | Pacific Northwest National Laboratory

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

An international team of researchers led by Michael Hochella Pacific Northwest National Laboratory suggests that the use of small organisms may be a solution to the urgent need to remove excess carbon dioxide from the Earth’s environment.

The team conducted an analysis published in the journal Nature Nanotechnologyon the possibility of seeding the oceans with iron-rich engineered fertilizer particles near ocean plankton, microscopic plants important in the ocean ecosystem, to increase phytoplankton growth and carbon dioxide absorption.

“The idea is to augment existing processes,” said Hochella, a lab associate at Pacific Northwest National Laboratory. “For centuries, people have fertilized the soil to grow crops. We can learn to fertilize the oceans responsibly.”

Michael Hochella

Michael Hochella is an internationally recognized environmental geochemist. Credit: Virginia Tech Photography Services

Nutrients from land in nature reach the oceans through rivers and blow dust to fertilize plankton. The research team now proposes to take this natural process a step further to help remove CO2 from the ocean. They examined evidence that adding specific combinations of carefully designed materials can effectively fertilize the oceans and encourage phytoplankton to act as carbon sinks. Organisms would take in large amounts of carbon. Then, as soon as they died, they took the excess carbon with them and sank it into the depths of the ocean. Scientists say this proposed fertilization would simply speed up a natural process that safely sequesters carbon from the atmosphere over thousands of years.

“Time is of the essence at this point,” Hochella said. “To combat rising temperatures, we need to reduce CO2 levels globally. Exploring all our options, including using the oceans as CO2 sinks, gives us the best chance to cool the planet.”

Taking ideas from 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 can help particles stick to plankton. Some particles also have light-absorbing properties that allow plankton to consume and use more CO2. The general approach can also be adjusted to meet the needs of specific ocean environments. For example, one region may benefit most from iron-based particles, while silicon-based particles may be most effective elsewhere, they say.

The researchers’ review of 123 published studies showed that multiple non-toxic metal-oxygen materials can safely enhance plankton growth. They argue that the stability, Earth’s abundance, and ease of creation of these materials make them viable choices as plankton fertilizers.

The team also analyzed the costs 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.

Reference: Peyman Babakhani, Tanapon Phenrat, Mohammed Baalousha, Kullapa Soratana, Caroline L. Peacock, Benjamin S. Twining, and Michael F. Hochella, “Potential Use of Engineered Nanoparticles in Ocean Fertilization for Large-Scale Atmospheric Carbon Dioxide Removal” November 28, 2022 Nature Nanotechnology.
DOI: 10.1038/s41565-022-01226-w

In addition to Hochella, the team included researchers from several research institutes located in England, Thailand and the United States. The research was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation program.

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