The underwater mass spectrometer was recently deployed at depths to 72m in Yellowstone Lake on an Eastern Oceanics remotely operated vehicle (ROV). Observations of dissolved vent gas compositions were obtained.

Distinct differences in dissolved vent gas composition point to a diverse set of geothermal conditions beneath the lake. Oxygen concentrations were low in most vents, while hydrogen sulfide, methane and carbon dioxide concentrations were highly variable. The observed rapid and sensitive responses to vent gas compositions indicate that the underwater mass spectometer is well suited to investigations of underwater vents and natural gas seeps.

In Yellowstone Lake, the mass spectrometer’s inlet filter was affixed to the end of the ROV’s extendable probe. The slides below indicate how the inlet filter was affixed to the probe.  In series a, 4 slides display the probe being extended into a geothermal vent located 69 meters below the lake’s surface. In series b, 4 slides show the ROV’s probe being extended into a geothermal vent located within a rock outcropping at a depth of 71 meters.

The graphs below indicate species concentration.   On the left, instrument response is seen in a low flow, 3m deep vent in Yellowstone Lake. Oxygen and carbon dioxide concentrations in the vent water were very low relative to surrounding lake water concentrations. 

On the right, instrument response is seen when deployed in a high flow, 30m deep vent in Yellowstone Lake. A strong positive response was detected for carbon dioxide, methane and hydrogen sulfide, but a negative response was observed for oxygen.