A REVIEW OF VOLTAMMETRIC SOLID-STATE MICROELECTRODE APPLICATIONS FOR REAL-TIME INVESTIGATION OF BIOGEOCHEMICAL PROCESSES IN NATURAL WATERS AND SEDIMENTS

Electrochemical techniques have often been used to study environmental processes. Over the past couple of decades, there has been a concentrated effort to develop electrodes and instrumentation for taking real-time measurements voltammetry and other techniques. Here we will briefly outline the major methods using electrodes in environmental chemical analysis, followed by a review and update of the applications of solid-state gold amalgam microelectrodes developed at the University of Delaware. These electrodes are capable of simultaneous, fine-scale resolution of multiple redox-sensitive analytes and selected trace metals (e.g. O₂, Mn²⁺, Fe²⁺, FeS(_(aq), HS^-/S₈/S_x^n-, I^-, Pb²⁺, Zn²⁺). For this talk, we will present the construction and application of these microelectrodes for sub-millimeter resolution measurements in marine and freshwater sediments, in metal contaminated salt marshes, in hypoxic/anoxic basins (Chesapeake Bay and the Black Sea) and at hydrothermal vents. The development of user-controlled and unattended in situ electrochemical analyzers will also be discussed.