Portable Underwater Mass Spectrometry

The Chemical Sensors group at SRI St. Petersburg is developing and operating underwater mass spectrometers for in situ measurements of dissolved gases and volatile organic compounds.

The underwater membrane inlet mass spectrometers have been deployed on a wide variety of platforms for a number of applications in oceanographic, estuarine and freshwater research. Types of deployments include the following:

• Stationary—time series chemical monitoring
• R/V winch—chemical depth profiles
• Surface vehicle—2-D chemical mapping
• AUV/ROV—3-D chemical mapping

We have developed a method to calibrate underwater mass spectrometers to make quantitative measurements of dissolved gases and volatile organic compounds to depths of 2000 meters. We created a model to describe the dependence of membrane permeability on hydrostatic pressure, which was then applied to in situ underwater mass spectrometer data to generate high-resolution, vertical profiles of dissolved gases. These measurements constitute the first quantitative observations of dissolved gas profiles in the oceans obtained by underwater mass spectrometry.

List of Publications