Vast quantities of methane are sequestered in the seabed globally. The Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research employs an underwater mass spectrometer (UWMS) called the Transpector Compact Process Monitor (CPM) by INFICON to explore methane origins. This system, known for its precision and rapid measurements, provided by a supplier of measurement and sensor technology, contributes to data reliability and user-friendliness.
Methane, a potent greenhouse gas (GHG), is being increasingly released into the atmosphere due to tipping point effects like the breakdown of gas hydrates in oceans. In aquatic environments, methane can rise to the surface through sediment cracks.
Another source of underwater methane is the microbial decomposition of organic matter in deeper sediment layers. As marine sediments warm due to climate change, they release more GHGs. The critical question is: how much methane is being released into the atmosphere, further fueling global warming?
Identifying Methane Leaks
The on-site use of an underwater mass spectrometer proves effective in pinpointing submarine methane sources. Key advantages include quick response times at high concentrations and up to 750 times faster measurement rates of dissolved gas concentrations compared to alternative methods. Greater data density leads to more accurate mapping of methane sources.
The UWMS comprises a membrane inlet system for sampling and a sensor unit for measuring water-soluble gases and light hydrocarbons, with a mass spectrometer at its core. The AWI Helmholtz Centre for Polar and Marine Research relies on INFICON’s Transpector CPM for their investigations.
South Atlantic Expedition
In December 2022, the research vessel Polarstern conducted methane source exploration in the South Atlantic using an underwater mass spectrometer. Dr. Torben Gentz, a scientist involved in the UWMS project at AWI’s marine geochemistry department since 2005, was on board. Today’s system has been significantly upgraded, with new control systems and vacuum pumps. Dr. Gentz noted that the only remaining component from the original setup is the Transpector CPM from INFICON.
Understanding the proportion of methane reaching the atmosphere is crucial for research, as it influences the assessment report of the Intergovernmental Panel on Climate Change (IPCC). Reliable measurement techniques are essential for determining the oceans’ role in the global climate system.
“Investigating methane sources is not the sole application,” mentioned INFICON service manager Steffen Tippmann.
Transpector CPM systems find uses in semiconductor production for process monitoring and control, as well as contamination monitoring in the semiconductor industry. Additionally, CPM systems are utilized in research, chemistry, material analysis, and physics. They can ionize directly at process vacuum or at significantly higher pressures than with an open ion source, requiring a differential pump system like the one in the CPM. A variable, switchable inlet system can cover a broad analysis pressure range from atmospheric pressure to high vacuum.
Closed Ion Source
Special applications, such as those at AWI, benefit from the closed ion source feature. Here, process gas is ionized at higher pressures than with an open ion source, resulting in a higher ion yield and more charged particles that can be separated by mass-to-charge ratio in the quadrupole and displayed. Tippmann highlighted that this yields more precise and detailed data for further analysis in research or process control.
Source: INFICON
