Measurements of dissolved gas concentrations such as carbon dioxide, methane, and hydrogen sulfide are critical to understanding volcanic, chemical, and biological processes in submarine environments. Carbon dioxide in magma chambers helps drive seafloor eruptions, and, along with methane and hydrogen sulfide, is key to supporting the subseafloor biosphere. Until recently, however, it has been impossible for scientists to measure these gases in situ for long periods of time. Scientists depended on taking individual samples from vents and seeps, and then analyzing them back in land-based laboratories.
In 2014 a novel mass spectrometer, developed by Peter Girguis at Harvard University, was deployed in a diffuse vent site (MJ03C) on Axial Volcano. MASSPA301 is sampling fluids from El Gordo vent within the International District I site, and the samples are being analyzing in situ. Other instruments at El Gordo include additional fluid samplers, a microbial DNA sampler, and a digital still camera.