Scientists identify potential deep-sea greenhouse gas storage solutions

As the planet continues to warm and the effects of human-induced climate change continue to grow, there is an increasing need to find ways to mitigate climate change. In Nature Communications, scientists at the University of California, Irvine describe a new technique that allows them to observe how complex organic molecules made by marine bacteria can store climate-warming carbon in the deep ocean. .

“This is the first time we’ve measured this kind of material in seawater,” said Brett Walker, associate professor in the Department of Earth System Sciences and senior author of the study. “Our new technique is great because it allows us to look at the composition of all the organic molecules in seawater and see how they cycle.”

Walker and his team conducted fieldwork in Baffin Bay, located between Canada and Greenland. The research team measured the concentration of a class of molecules called carboxyl-rich alicyclic molecules (or CRAMs) in seawater, and found that certain types of organic molecules are preferentially stored in the deep ocean, while other types of organic molecules are preferentially stored in the deep ocean. They discovered that the molecules rapidly circulate to the surface.

“We know that about a quarter to half of CRAM is lost in the deep ocean, and the only way it can be removed is biologically, through heterotrophic bacteria eating this material for energy. ,” Walker said.

“We previously thought that CRAM was accumulating in the deep ocean. But when we look at the concentration data we have produced for Baffin Bay, a very different picture emerges. At least in this Arctic region. In Baffin Bay, we found that there is indeed a large amount of CRAM.” CRAM is produced in the sunlit surface ocean and then removed at depth. ”

Conversely, if half of the CRAM is stored unreacted in the deep ocean, this could mean that bacteria can store global warming carbon derived from surface CO2 over very long time scales.

“This changes the way we’ve traditionally thought about how CRAM cycles work,” Walker says. “If we could store more CRAM in the deep ocean, we could potentially mitigate atmospheric climate on a 100-year scale.”

The next step is to find a way to manipulate bacteria to store as much CRAM as possible in the deep ocean.

“The goal is to investigate whether there are natural processes deep within natural bacterial populations that can enhance the natural production of these inert compounds,” Walker said. “Small increases in deep-sea storage rates could dramatically change carbon stocks over thousands of years.”

Walker and his colleagues plan to find out whether the same biochemical processes are at work in seawater around the world. “We plan to assess the production and loss rates of CRAM as the deep ocean forms and ocean circulation occurs,” he said.