Gartzman_4December_2017 |
Gartzman_4December_2017
Graduate School of Oceanography - OCG 695
4 December 2017, 3:30 PM Corless Auditorium
4 December 2017, 3:30 PM Corless Auditorium
In-situ Calibration of Underwater Membrane Inlet Mass Spectrometer for Simple Dissolved Gases
Abstract: The Underwater Mass Spectrometer (UMS) provides unprecedented resolution and measurement detail for volatile compounds, including dissolved gases. However, interpretation of the measurements requires attention to several instrumental and environmental effects. We have developed a new calibration method to both measure and model the influence of hydrostatic pressure, instrument internal temperature, electronic noise and external water temperature changes. We use an in-situ calibration method that allows continuous sampling from a dissolved gas standard; the UMS and in-situ calibration were twice deployed on a tow vehicle to capture saw-tooth profiles throughout the euphotic zone. The primary atmospheric gases - N2, O2, and Ar - were measured while sampling from the calibration system to examine independent variables (pressure, internal temperature, electronic baseline, and external water temperature) that cause variability in the UMS readings. Principal component analysis was used to evaluate sources of variability and 3rd order polynomial fits were made when sampling. These fits have shown to successfully correct UMS readings to calibrate for ambient sampling. In-situ calibration allows for continuous, high fidelity measurements and better tracing of dissolved gases in the ocean.
Abstract: The Underwater Mass Spectrometer (UMS) provides unprecedented resolution and measurement detail for volatile compounds, including dissolved gases. However, interpretation of the measurements requires attention to several instrumental and environmental effects. We have developed a new calibration method to both measure and model the influence of hydrostatic pressure, instrument internal temperature, electronic noise and external water temperature changes. We use an in-situ calibration method that allows continuous sampling from a dissolved gas standard; the UMS and in-situ calibration were twice deployed on a tow vehicle to capture saw-tooth profiles throughout the euphotic zone. The primary atmospheric gases - N2, O2, and Ar - were measured while sampling from the calibration system to examine independent variables (pressure, internal temperature, electronic baseline, and external water temperature) that cause variability in the UMS readings. Principal component analysis was used to evaluate sources of variability and 3rd order polynomial fits were made when sampling. These fits have shown to successfully correct UMS readings to calibrate for ambient sampling. In-situ calibration allows for continuous, high fidelity measurements and better tracing of dissolved gases in the ocean.
Sam Gartzman earned a B.S. in Environmental Chemistry from Beloit College in 2016. He entered GSO in Fall 2016 and is in the M.S. program. His major professor is Brice Loose.