Profiling Sensor to Map N2 Gas Production in OMZs - EX1709

Oxygen Minimum Zones (OMZs) play important roles in regulating the ocean's global carbon and nitrogen cycles. In these functionally anoxic waters, denitrifying and anammox microbes remove nitrogenous nutrients from the biosphere by transformation to biologically unavailable nitrogen gas (N2). For this project, scientists developed a new in situ profiling sensor to detect this 'excess' N2 in OMZ regions in order to quantify these N-loss processes. The new sensor incorporated recent but reliable and proven technical advances in membrane and pressure sensor technologies, and therefore its development was relatively low risk. Compared to existing, slow response sensors, the new sensor had low production cost and could easily be added to any ship's rosette CTD. Scientists' near-term goal was to demonstrate the sensor on two NOAA research vessels and begin to collect high-quality excess N2 data in OMZs to document baseline excess N2 inventories. Their long-term goal was to determine if excess N2 inventories in OMZs are increasing as a result of ocean deoxygenation. It was expected that the new sensor can be easily adapted for use on other profiling platforms (autonomous underwater vehicles, remotely operated vehicles, winched profilers, etc.) and be used more widely to study air-sea gas flux and net community metabolism. Funding for this project was provided by NOAA Ocean Exploration via its Ocean Exploration Fiscal Year 2016 Funding Opportunity.