This EAGER project will provide an assessment of the potential use of a high resolution proton transfer time of flight mass spectrometer (PTR-TOFMS) for eddy covariance air/sea gas flux measurements. The composition and rates of emissions of volatile organic compounds from the sea surface are poorly known, which is in large part due to the lack of suitable instrumentation for measuring such fluxes. The PTR-TOFMS will be deployed under field conditions aboard the R/V Knorr in the North Atlantic Ocean. If successful, this will demonstrate the viability of the approach to future field programs. The project may also result in the first broad-spectrum analysis of fluxes of volatile organic compounds emanating from a highly productive oceanic region. This could provide access to new tracers for air/sea gas exchange and insight into the precursors of secondary marine organic aerosols.
This project will provide support for a post-doctoral researcher, as well as involve at least one undergraduate student who is participating in the institution's REU site program.
The goal of this project was to test a newly available commercial instrument (Ionicon high resolution, time of flight proton transfer mass spectrometer) for the measurement of air/sea trace gas fluxes. This instrument was theoretically capable of detecting a wide range of organic analytes at low levels and high frequency. The instrument was deployed aboard the research vessel R/V Knorr in the North Atlantic Ocean as part of the BloomCruise field experiment. Analysis of the resulting data indicated that the instrument detected trace gases, however, the sensitivity required for air/sea gas exchange studies was not achieved. As an alternative approach, we explored the use of ion funnel technology as a means of increasing the sensitivity of existing instrumentation in our laboratory. We partnered with DOE PNNL laboratory to migrate their patented ion funnel technoloqy into a UCI-built chemical ionization mass spectrometer. Laboratory and field tests demonstrated greatly enhanced sensitivity. This approach will help achieve the original goal of extending our ability to make air/sea flux measurements to a wider range of gases. As an example, we carried out direct flux measurements of sulfur dioxide from the Scripps Pier. We have successfully demonstrated that sub-ppt level measurements can be carried out with the newly developed UCI chemical ionization mass spectrometer with ion tunnel.
