Development and application of an underwater mass spectrometer for in situ detection of deep-sea dissolved gases

The rapid and accurate analysis of dissolved gases in the deep sea has great significance for studying the geological profile of the Earth, searching for oil and gas resources, and studying global climate change. In this research, we developed a deep-sea mass spectrometer for in situ dissolved gases detection. The deep-sea mass spectrometer uses 24 V DC power and has an average power consumption of less than 60 W during operation and less than 10 W during standby. Its physical size is φ240 mm×1300 mm, with a core mass of 14.2 kg. The detectable mass range is 1–200 Da, with a mass resolution of less than 1 Da and the scanning time for a single mass is less than 15 ms. The detection limits for dissolved N₂, O₂, Ar, and CO₂ under atmospheric pressure are 0.021 μg/L, 0.068 μg/L, 0.017 μg/L, and 0.014 μg/L. The deep-sea mass spectrometer operated continuously and stably for more than 8 h under a simulated water depth of 5800 m, and it also achieved continuous online detection for 25.8 h in the sea area of −1388 m depth in the South China Sea, obtaining dissolved gas concentration-time and depth-concentration curves. This research provides key technological support for deep-sea exploration and information reference for other deep-sea detection technologies.