🌊 The "Missing Piece" of the Ocean Carbon Cycle Has Been Found
The ocean is Earth's largest active carbon sink, absorbing approximately one-third of human-induced CO2 emissions. However, in the sunless depths of the deep sea, how exactly is carbon fixed? For years, the scientific community has grappled with an "energy imbalance" in carbon accounting that simply didn't add up.
A groundbreaking study from the University of California, Santa Barbara (UCSB), published in the leading journal Nature Geoscience in December 2025, has finally solved this decade-long mystery and overturned textbook understanding of deep-sea ecosystems.
🔬 Key Finding: The "Slash" Function of Heterotrophic Microbes
Previously, scientists generally believed that carbon fixation in the deep sea was primarily carried out by autotrophic archaea, which utilize energy from ammonia oxidation to convert CO2 into organic matter. However, the research team discovered that there is simply not enough nitrogen in the deep sea to support the observed levels of carbon fixation.
Through sophisticated inhibition experiments, the team made a startling discovery:
A Shift in Lead Roles: The contribution of ammonia-oxidizing archaea, traditionally considered the primary fixers, has actually been overestimated.
The Unexpected "Dark Horse": The true heavy lifters in carbon fixation turned out to be heterotrophic microbes. While typically classified as "consumers" or "decomposers" that feed on organic carbon, this new study confirms that these microbes "moonlight" by fixing inorganic carbon (CO2) in deep-sea environments.
🌍 Why This Matters
This discovery rewrites our understanding of the ocean carbon cycle:
Refining Climate Models: Identifying the true primary drivers of deep-sea carbon fixation allows us to more accurately assess the ocean's capacity to combat global warming.
Ecosystem Stability: This reveals that the foundation of the deep-sea food web is more complex and resilient than previously imagined; it underscores that heterotrophic organisms play a far more significant role in stabilizing Earth's climate than anticipated.
圖片/資料來源: https://www.sciencedaily.com/releases/2025/12/251210092024.htm
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