In-Situ Chemical Sensors for Monitoring the Chemistry of Hydrothermal Vent Fluids at Mid-Ocean Ridges: Instrument Development and Field Applications

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Abstract: Ding (0525907)Intellectual Merit: The ability to measure and monitor changes in the chemistry of waters from extreme environments is a major technological and scientific challenge. This research continues an ongoing effort to develop, calibrate, test, and deploy in situ electrochemical sensors for pH, temperature, and important Hydrogen and sulfur-bearing redox compounds, with the goal of producing an instrument package that can be used for long term monitoring of hydrothermal vent chemistry at mid-ocean ridges. Prototype testing of the instrument has been successful and measured, in real time, the in situ pH and H2 and H2S concentrations of waters emanating from high and low temperature, diffuse-flow vents. This work will extend the monitoring capabilities of the sensor array and increase its physical robustness for long-term deployment on the seafloor. Field test sites will be high temperature and low temperature diffuse flow vents on the East Pacific Rise and low temperature vents at Lost City or the Rainbow site on the Mid Atlantic Ridge. Long-term lab testing of the material properties of the sensors will be carried out for the solid-state pH sensor and results will be disseminated widely to build a user base. Specific project goals include in-situ computer controlled calibration of the present high temperature sensor package and the development of a solid-state pH sensor, which is better suited for long-term use in high pH and biologically active hydrothermal vent areas. The first year of the program will be devoted to technical upgrades of the present chemical sensor system. Field deployments and testing of the sensor packages will take place in years two and three at the EPR 9N and MAR hydrothermal sites using submersibles and/or ROVs.Broader Impacts: This work funds researchers and students at the University of Minnesota. Broader impacts consist of new sensor/tool development and application of the tools in environments previously too hostile, in terms of temperature, pressure, corrosive chemistry and/or biofouling, to be sampled and measured in-situ. As such, this work enhances research infrastructure available to the ocean sciences community, especially with regard to making crucial time series measurements of inherently dynamical processes linked to energy and mass transfer at mid-ocean ridges.