地球大气氧含量从无到有奥秘揭示

Core Insights - The research conducted by Nanjing University and international collaborators reveals the evolutionary history and control mechanisms of Earth's atmospheric oxygen transition from anoxic to oxic conditions, providing critical geochemical indicators for understanding the origin and evolution of life on Earth and its habitability [1][2] Group 1: Research Findings - The study established a high-resolution record of sulfate triple oxygen isotopes, which can trace changes in ancient atmospheric oxygen levels [1] - The research team created a nearly 3 billion-year record of triple oxygen isotope evolution, indicating three significant transitions in atmospheric oxygen content occurring in the Paleoproterozoic (2.4 to 2.1 billion years ago), Neoproterozoic (around 1 billion years ago), and Paleozoic (around 440 million years ago) [1] - The atmospheric oxygen levels rose in stages, stabilizing at a near-oxic state approximately 410 million years ago [1] Group 2: Mechanisms of Change - Following the increase in atmospheric oxygen, there was a periodic oxidation of anoxic oceans, promoting the oxidation of organic carbon and reduced sulfur in anoxic waters, leading to significant isotopic disturbances [2] - This process rapidly consumed large amounts of oxygen through negative feedback mechanisms, inhibiting or even reversing further increases in atmospheric oxygen levels [2] - The research quantitatively reconstructed the evolutionary history of Earth's atmospheric oxygen content, revealing the dynamic coupling and co-evolution mechanisms between atmospheric and oceanic oxidation states [2]