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As you read this story, you will learn the following:
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Although most dissolved inorganic carbon fixation occurs at the ocean surface, some of this fixation budget comes from the deep ocean.
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In a new study, scientists believe microbial heterotrophs are helping ammonia-oxidizing autotrophs fix inorganic carbon in the deep ocean.
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This helps us better understand deep-sea food webs and the ocean’s carbon storage capacity.
When it comes to cooling our warming planet, the name of the game is to suck as much carbon out of the atmosphere as possible, and the ocean is the undisputed GOAT when it comes to playing this carbon sequestration game. according to To the United Nationsthe ocean absorbs more than 30% of all carbon dioxide emissions and A significant 90% of the excess heat generated by these emissions is noticeable. Humanity has no greater ally in the fight against climate change.
However, scientists are still pondering the various mechanisms the deep ocean uses to sequester carbon. Most inorganic carbon fixation occurs at sea level, thanks to surface phytoplankton, which, like other terrestrial autotrophs (i.e., organisms that make their own food), produce organic sugars and oxygen in exchange for carbon dioxide. However, some non-photosynthetic fixation also occurs in the deep ocean. The prevailing theory has long been that archaea capable of oxidizing ammonia for energy continued this carbon-fixing job No Need for sunlight. However, when you break down the numbers, you’ll find that something doesn’t add up.
“There’s a discrepancy between what people measure when they go out on boats to measure carbon fixation and what we understand about microbial energy,” said Alyson Santoro, a microbial oceanographer at the University of California, Santa Barbara (UCSB) and senior author of a new paper in Nature. natural geosciences Investigate this difference, say in press statement. “We basically don’t have access to the budget for organisms that fix carbon.”
In other words, these deep-sea autotrophs need nitrogen-based energy to fix carbon, but the data suggest there simply isn’t enough energy for ammonia-oxidizing autotrophs to be the only source of fixation. Rather than investigating whether these autotrophs are more efficient in this process than we realized (spoiler, they’re not), the researchers asked a different question: Are ammonia oxidizers the only organisms capable of fixing carbon?
To answer this question, Santoro and her team, which included lead author Barbara Beyer of the University of Vienna, inhibited these oxidants with the chemical phenylacetylene. If these autotrophs were the dominant source of stationary, these ratios should drop dramatically. However, interest rates did not fall almost As expected, the researchers believe microbial heterotrophs in the deep sea must have played a role.
“This is really interesting because even though we knew it was a theoretical possibility, we didn’t really have a quantitative number on what proportion of the carbon in the deep ocean is fixed by these heterotrophs versus autotrophs. Now we know,” Santaro said in a press statement. “I think it’s about figuring out how the basis of the deep-sea food web works.”
Although the ocean is absorbing as much carbon as possible, there is no free lunch. A study earlier this year reported that even under an ideal climate scenario – a future in which humans become net negative – the Southern Ocean could “suck” excess heat over decades or even centuries at levels that mimic anthropomorphic climate change. While this kind of ocean indigestion is likely to be in our future, working toward carbon neutrality to limit these worst climate consequences remains critical.
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