Recently, a team led by Dr. Chen Chilai, a researcher at the Institute of Intelligent Materials, Hefei Institutes of Physical Science, Chinese Academy of Sciences, has achieved a breakthrough in deep-sea exploration. Building upon previous research in deep-sea mass spectrometry, they have amplified the sensitivity of methane detection in water by over 500 times. This advancement now enables the detection of dissolved methane in oceans and lakes at baseline levels, facilitating the transition from monitoring anomalous dissolved methane events to long-term background methane monitoring. The related technology has been filed for a national invention patent, and the research findings were recently published in the academic journal "Talanta".
The "Intelligent Microprobe" deep-sea mass spectrometer conducted sea trials with a relay. Image provided by the Institute of Intelligent Automation, Hefei Institutes of Physical Science, Chinese Academy of Sciences.
Methane, as the second-largest greenhouse gas after carbon dioxide, has significant impacts on global climate change. Approximately 53% of methane emissions annually come from aquatic ecosystems such as oceans and lakes, making it crucial to effectively monitor methane emissions from the ocean to the atmosphere. Additionally, methane is a primary component of natural gas hydrates, a promising clean energy source for the 21st century. Therefore, monitoring marine methane is of great value for ocean environmental awareness, identifying methane anomalous areas, marine energy exploration, and oceanographic research.
Due to the low and variable concentrations of methane in the ocean, there is still limited data on dissolved methane in the ocean, leading to significant uncertainties in estimating marine methane fluxes. The deep-sea mass spectrometer is an important oceanic device for rapid detection of dissolved gases. However, due to its limited detection sensitivity, it can only detect specific regions or anomalous events.
In 2023, the team led by Chen Chi developed a deep-sea mass spectrometer named "Intelligent Microprobe" and successfully completed multiple sea trials in a certain area of the South China Sea, obtaining crucial dissolved gas information along ocean profiles. Building upon previous work, to further enhance detection sensitivity, the team addressed issues such as high sample water vapor and limited space of detection instruments. They developed a small-volume, low-power online water removal system and optimized the gas sampling path, successfully integrating them into the Intelligent Microprobe deep-sea mass spectrometer. This improvement not only maintained the high permeation flux of the target detection gas but also increased the vacuum level of the mass spectrometer by over 2 orders of magnitude. As a result, the methane detection limit was reduced from above 16 nanomoles per liter to 0.03 nanomoles per liter, a more than 500-fold improvement. This achievement brings the detection capability of methane background signals in deep-sea and lake environments to a level where indiscriminate monitoring of dissolved methane in the ocean becomes feasible.
It is reported that the research team's next step is to conduct in-situ detection research on background methane over a large spatial and wide temporal range based on this technology, as well as research on directed ultra-low concentration gases such as H2 and He. This research provides an important technical foundation for further methane flux calculations, global climate research, plume tracking, and cold seep discoveries.
Related paper information: https://doi.org/10.1016/j.talanta.2024.125907
