A Continuous Flow Electrochemical Cell for Analysis of Chemical Species and Ions at High Pressure: Laboratory, Shipboard, and Hydrothermal Vent Results

摘要

An inexpensive and rugged voltammetric flow cell has been developed to test pressure dependence and flow rate on current vs. concentration standard curves and for the simultaneous measurement of electroactive species in field samples. Standard curves show that current is independent of pressure but varies with the square root of the flow rate. The electrochemical system consists of a pump to deliver water into a voltammetric flow cell with a standard three-electrode arrangement that is controlled by a voltammetric analyzer. The flow cell can be used onboard ship or in situ at any depth including from the deep-sea submersible, Alvin. Field samples were analyzed for a variety of redox species under controlled flow conditions with a solid state working electrode at a depth of 2500 m. In this study, a 100 μm Au/Hg amalgam solid-state working electrode is used to detect dissolved O_2, S(-II), Fe(II) and Mn(II). We describe the flow cell and its capabilities.