This project is developing an underwater coded aperture miniature mass spectrometer (UW-CAMMS) using a cycloidal mass analyzer, spatial aperture coding, and a focal plane array detector that will improve sensitivity, resolution, and power requirements compared to the current state of the art underwater mass spectrometers used for in situ measurements of dissolved gases in the ocean. Once developed, UW-CAMMS will be useful for and easily adapted to a wide variety of underwater and/or shipboard based analyses). However, for the purposes of this project we will focus on improving the state of the art for measurements of dissolved methane to help address the extent of methane attenuation in the vertical column, and the proportion of methane from gas hydrates reaching the atmosphere. The three objectives are listed below:

1.  Design, fabrication, and calibration of a high-pressure membrane inlet for sampling dissolved gases in water using a mass spectrometer.

2.  Design and fabrication of an UW-CAMMS system including cycloidal mass analyzer, ion source with spatial aperture coding, ion array detector, membrane inlet from objective #1, control electronics, control software, battery power supply, vacuum system, and pressure vessel.

3.  Test performance of UW-CAMMS subcomponents and full system in the field.

·   Phase 1: Test performance of calibrated membrane inlet from objective #1 with the previously constructed CAMMS-ES.

·   Phase 2: After completion of objective 2, test UW-CAMMS full system functionality in a relevant environment by operating submerged in a tank filled with fresh water.

·   Phase 3: Deploy UW-CAMMS on the R/V Shearwater on a brief 1-2 day field campaign to observe a methane seep near Bodie Island off the coast of North Carolina.

·   Phase 4: Deploy UW-CAMMS on the R/V Shearwater to study methane concentration profiles in waters above Blake Ridge on a 5-7 day field campaign.

This project is funded by NSF award 2123556 https://www.nsf.gov/awardsearch/showAward?AWD_ID=2123556