Discovery of supercritical carbon dioxide in a hydrothermal system.

Supercritical CO appearing as bubbles in hydrothermal vents was identified in the south part of the Okinawa Trough using in situ Raman spectroscopy. Significantly, the N peak in supercritical CO is much larger than those in seawater and vent fluids, indicating that supercritical CO enriches N from the surrounding environment. Considering that the partial pressures of CO and N in the Earth's proto-atmosphere were ~10-20 MPa, supercritical CO with high N was likely the dominant CO phase near the water-air interface in the early history of the Earth, which promoted the synthesis, pre-enrichment and preservation of amino acids and other organic matters that are essential to the origin of life.