SCUID - a Platform for In-Situ Dissolved Gas Measurement of N2O and NO

Anuscheh Nawaz1, Mark Andrew Barry2, Philip Colosimo3, Steve Kahle4, Jing Li5 and Craig McNeil1, (1)Applied Physics Laboratory University of Washington, Seattle, WA, United States, (2)Pro-Oceanus, Bridgewater, NS, Canada, (3)Applied Physics Laboratory University of Washington, Ocean Engineering Department, Seattle, United States, (4)Applied Physics Laboratory University of Washington, Seattle, United States, (5)NASA Ames Research Center, Moffett Field, CA, United States
While it is possible today to measure trace gases such as N2O, NO, and DMS in the atmosphere, the sensors to measure dissolved gases in seawater real time and in situ are limited to CO2, CH4, and H2S. Measurement of climatically relevant trace gases are necessary to quantify ocean sources and sinks, and to understand their impact on global climate change. In particular, there is a critical need for a deeper understanding of gas cycling in hypoxic zones. N2O is a known greenhouse gas and can therefore feed back on global warming via increased OMZ expansion (1). Today highly precise measurement of dissolved gases like N2O and NO rely on laboratory based analyses such as mass spectrometry and gas chromatography.

This work introduces SCUID (Submergible Carbon nanotube Underwater Instrument for dissolved gas Detection) to the oceanographic instrumentation community. SCUID is a small, low-power, real time dissolved gas sensor system that is deployed via the ship’s CTD, can ultimately be tuned to different gases of interest, and allows for high spatial resolution sampling.

The SCUID sensor marries two mature concepts: the ProOceanus pressure housing, and the NASA-Ames developed carbon nanotube (CNT) sensor. Carbon nanotube based gas sensors are considered cutting edge technology, allowing to detect a wide range of environmental and safety related trace gases at relevant sensitivities.

They are low power, and have provided in-situ, real time, automated measurement of chemicals in space, for fire detection, for fuel leak detection, and as health monitoring system. The technical and scientific approach, as well as the current status of the SCUID instrument development will be presented in the proposed paper.

(1) Bange H, Freing A, Kock A, Löscher C., Marine pathways to nitrous oxide, Nitrous oxide and climate change (ed. Smith K, editor. ), pp. 36–62 London, 2010