NEREUS/Kemonaut, a mobile autonomous underwater mass spectrometer
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NEREUS is a self-contained underwater membrane-inlet mass spectrometer (MS) based on a cycloidal mass analyzer. Designed for autonomous operation, with a mass of 22 kg and a power consumption of less than 20 W, a NEREUS prototype was demonstrated in freshwater and marine environments to a depth of 25 m. The instrument was operated in both tethered and towed operation, as well as aboard Kemonaut, an Odyssey-class autonomous underwater vehicle (AUV) modified to accommodate the NEREUS instrument. The Kemonaut AUV greatly expands the range of environments that can practicably be investigated. NEREUS was demonstrated to measure many important metabolic gases, such as oxygen, methane, and carbon dioxide, at levels encountered in natural waters; it also responds to light hydrocarbon pollutants. Important goals for future instruments are increased capability to self-calibrate in situ and lowered detection limits that enable measurement of trace metabolic gases, such as hydrogen and nitrous oxide. (C) 2004 Published by Elsevier B.V.