Nanoparticle iron-based fertilizer 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 using tiny organisms could be a solution to meet the pressing need to remove excess carbon dioxide from the Earth’s environment.
The team conducted an analysis, published in the journal Nanotechnology of natureabout the possibility of seeding the oceans with iron-rich fertilizer particles near ocean plankton, microscopic plants crucial in the ocean ecosystem, to stimulate phytoplankton growth and carbon dioxide uptake.
“The idea is to augment existing processes,” said Hochella, a lab fellow at Pacific Northwest National Laboratory. “Humans have fertilized the soil to grow crops for centuries. We can learn to fertilize the oceans responsibly.”
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 one step further to help remove excess CO2 through the ocean. They studied evidence suggesting that adding specific combinations of carefully designed materials could effectively fertilize the oceans by encouraging phytoplankton to act as a carbon sink. Organisms would take up carbon in large quantities. Then, as they die, they 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.
“Right now, time is of the essence,” Hochella said. “To combat rising temperatures, we need to reduce CO2 levels on a global scale. Examining all our options, including using the oceans as a CO2 sink, gives us the best chance of cooling the planet.”
Extracting insights 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 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 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 numerous non-toxic metal-oxygen materials could safely enhance plankton growth. The stability, Earth abundance 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 unengineered materials, it would also be significantly more efficient.
Reference: “Potential Use of Engineered Nanoparticles in Ocean Fertilization for Large-Scale Atmospheric Carbon Dioxide Removal” 28 Nov 2022, Nanotechnology of nature.
In addition to Hochella, the team included researchers from England, Thailand and several research institutions in the US. The study was funded by the European Research Council under the European Union’s Horizon 2020 research and innovation programme.