Engineered nanoparticles can help phytoplankton kidnap the excess CO2 on Earth

The solution to our carbon problem is floating in the oceans.
Rupendra Brahambhatt

Wikimedia Commons 

Phytoplankton are microscopic organisms (can be bacteria, algae, or plants) that perform photosynthesis in oceans and eliminate excess carbon dioxide from Earth's atmosphere. They sequester about 40 percent of the total carbon produced every year globally and, therefore, also play a major role in mitigating global warming. 

A team of researchers from the Pacific Northwest National Laboratory (PNNL) has proposed that by feeding engineered nanoparticles (ENPs) as fertilizers to phytoplankton. Humans can increase the growth of these microorganisms in oceans and eventually fix more CO2 from Earth than ever. 

A brief reminder of the ongoing threat

In order to fight the ongoing climate crisis, reducing carbon emissions in just a couple of regions of the world won't work. We need to lower carbon emissions globally. However, since different countries have different priorities, bringing them on the same page to achieve this goal seems nearly impossible. 

For instance, out of 200 countries that participated in COP27, over 80 percent of them failed to update their climate commitments as per the UN deadline. 

There is an unignorable trail of broken commitments. Plus, the pandemic and the Russia-Ukraine war have worsened the situation further. Many countries are currently facing energy and food crises, making it difficult for them to focus on their climate goals. 

However, we can not keep on delaying our climate actions. There is enough scientific evidence to prove that we may end up witnessing uncontrollable heatwaves, superstorms, droughts, famines, pandemics, and many other never-before-seen calamities.  

One of the authors and a geoscientist at PNNL,  Michael F. Hochella Jr., said, "At this point, time is of the essence. To combat rising temperatures, we must decrease 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."

Engineered nanoparticles can save us

Engineered nanoparticles can help phytoplankton kidnap the excess CO2 on Earth
Diagram depicting how ENPs promote phytoplankton growth.

Since phytoplanktons thrive in a human-free habitat and have the capacity to store large amounts of CO2, they are probably one of our best bets for curbing the growing carbon emissions, and the researchers believe they can accelerate the existing carbon fixation mechanism of phytoplankton. 

All they need to do is fertilize the oceans with the right ENPs in the right concentration to increase phytoplankton growth, similar to how land is fertilized to grow crops in large amounts. 

So while researching ways to increase the phytoplankton-driven carbon fixation process, Hoschella and his team examined 123 published works that dealt with ENPs' role in oceans and phytoplankton growth.  

They found that fertilizing oceans with non-toxic aluminum oxide (Al2O3), silicon dioxide (SiO2), or iron-based nanoparticles can boost phytoplankton growth. Also, it won't be a one-time process. In order to remove substantial amounts of carbon from our atmosphere, scientists may need to fertilize the oceans not just once but many times with these ENPs. 

The researchers reveal that there are numerous other ENP fertilization approaches involving different materials. They happen to be two to five times less expensive than the iron or silicone dioxide-driven methods, but they are also less effective. Since materials like silicon have great light-absorbing power, they allow phytoplanktons to capture more sunlight, grow faster, and sequester more carbon.  

To figure out the exact cost and risks associated with their current ENP approach, scientists need to test them in real-world conditions. The authors also look forward to developing ENPs that could perform even better than the proposed ones. Therefore, more research is required before we finally deploy these engineered ocean fertilizers to save our planet.   

The study is published in the journal Nature Nanotechnology.

Study abstract:

Artificial ocean fertilization (AOF) aims to safely stimulate phytoplankton growth in the ocean and enhance carbon sequestration. AOF carbon sequestration efficiency appears lower than natural ocean fertilization processes due mainly to the low bioavailability of added nutrients, along with low export rates of AOF-produced biomass to the deep ocean. Here we explore the potential application of engineered nanoparticles (ENPs) to overcome these issues. Data from 123 studies show that some ENPs may enhance phytoplankton growth at concentrations below those likely to be toxic in marine ecosystems. ENPs may also increase bloom lifetime, boost phytoplankton aggregation and carbon export, and address secondary limiting factors in AOF. Life-cycle assessment and cost analyses suggest that net CO2 capture is possible for iron, SiO2 and Al2O3 ENPs with costs of 2–5 times that of conventional AOF, whereas boosting AOF efficiency by ENPs should substantially enhance net CO2 capture and reduce these costs. Therefore, ENP-based AOF can be an important component of the mitigation strategy to limit global warming.

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