Alkaline sodium hydroxide was dumped into the Gulf of Maine to check its impact on carbon uptake and marine life
Daniel Cojanu, Undercurrent Productions, ©Woods Gap Oceanographic Establishment
Can we safely take away carbon dioxide from the ambiance by counteracting ocean acidification? Possibly, suggests a trial wherein ships poured 65,000 litres of alkaline sodium hydroxide into the Gulf of Maine off the East Coast of the US in August 2025.
“We’re the primary group to do a ship-based alkalinity enhancement experiment,” says Adam Subhas on the Woods Gap Oceanographic Establishment in Massachusetts, whose crew introduced their preliminary findings on the Ocean Sciences Assembly in Glasgow, UK, on 25 February. “We will positively say that there was extra CO2 uptake because of this experiment.”
Between 2 and 10 tonnes of CO2 was faraway from the ambiance within the following 4 days, Subhas says, and the crew estimates that as much as 50 tonnes could possibly be eliminated altogether. What’s extra, no vital impact on marine life was seen.
Nevertheless, when requested by New Scientist, Subhas acknowledged that the crew has but to estimate the emissions required to fabricate the sodium hydroxide and transport it to the trial web site. This implies it’s unclear whether or not the trial resulted in a web removing of CO2.
“It’s a very good query,” mentioned Subhas. “That’s going to be a very important space of analysis transferring ahead.”
The oceans retailer 40 instances as a lot carbon because the ambiance and have soaked up greater than 1 / 4 of the surplus CO2 we now have been pumping into the ambiance. This further CO2 reacts with water to type carbonic acid, which means that the oceans have gotten extra acidic.
Ocean acidification may have a serious affect on many marine organisms, as an illustration, by dissolving their carbonate shells. It additionally reduces the flexibility of the seas to take up extra CO2.
Researchers are exploring a lot of strategies to counteract ocean acidification, together with including magnesium hydroxide to wastewater that goes into the ocean, including ground-up olivine to coasts and pumping seawater by land-based remedy vegetation. Some corporations are already promoting carbon credit based mostly on alkalinity enhancement.
“That is one thing that the personal sector is transferring ahead with proper now,” says Subhas, which is why there’s a want for non-commercial trials just like the one his crew did.
Due to the controversial nature of those sorts of trials, the crew began by partaking with native individuals, notably within the fishing neighborhood, says crew member Kristin Kleisner of the Environmental Protection Fund, a non-profit organisation based mostly in New York. “Two-way dialogue is actually important,” she says.
The trial itself concerned three ships and was monitored in a number of other ways, starting from satellites to floating sensors to ocean gliders that zigzag up and down. The sodium hydroxide was blended with hint portions of a dye referred to as rhodamine, to assist precisely observe its dispersal.
The crew measured the concentrations of microbes, plankton, fish larvae and lobster larvae, and likewise the extent of photosynthetic exercise, says Rachel Davitt at Rutgers College in New Jersey. “There was no vital affect of our area trial on the organic neighborhood,” she says.
The additional carbon taken up by the ocean because of the elevated alkalinity is became bicarbonate ions, or dissolved baking soda, Subhas says. “We anticipate that this carbon is locked away for tens of 1000’s of years. It’s one of the vital sturdy types of carbon removing.”
The character of the method signifies that CO2 is eliminated and saved in a single step, Subhas says. This is a bonus over another approaches, the place CO2 is first faraway from the ambiance after which needs to be completely saved in some type.
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