Collaborative Research: Development of a Porewater Sampling Underwater Mass Spectrometer System (POSUMS) for High-Resolution Biogenic Gas Measurements in Permeable Sediments 

At present there is a disconnect between what we understand about permeable sediment biogeochemistry from small-scale manipulations and how we represent continental shelf biogeochemistry in a modeling framework.  The “missing link” is a set of reliable tools to measure dynamic processes in the field, and thus to provide good data and a basis for appropriate parameterization for modeling. The instrumentation we will build  will overcome several of the present limitations of porewater sampling in permeable sediment environments. The system is designed to operate in situ (on site) without enclosure artifacts. It will to sample over extended time periods, making it more likely to capture transient events that may dominate sediment-water exchange.  And because the sampling interface is coupled to a mass spectrometer, the system can collect accurate and precise data for multiple chemical species simultaneously.  

The primary purpose of our proposed research is to develop a system that meets the following research demands: 

1. Operate in situ (no core recovery)
2. Not interfere with the advection field (no enclosure artifacts)
3. Have extended sampling endurance (to capture transient events and the range of geochemical responses to external forcing)
4. Adaptively alter sampling regimes to accommodate changes in environmental forcing (e.g., advective flow)

Check out our YouTube channel for updates on our progress!

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A trial run of the first-generation porewater sampling device, deployed in 2008 by SRI and Skidaway Institute of Oceanography.