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OPTIMIZATION OF VOLTAMMETRIC METHODS FOR AN IN SITU DETERMINATION OF TOTAL SULFIDE IN ANOXIC POREWATER USING A MERCURY PLATED GOLD ELECTRODE
Citation:
Howell, K. A., C. E. Reimers, H. A. Stecher, Y. Alleau, AND M G. Johnson. OPTIMIZATION OF VOLTAMMETRIC METHODS FOR AN IN SITU DETERMINATION OF TOTAL SULFIDE IN ANOXIC POREWATER USING A MERCURY PLATED GOLD ELECTRODE. Presented at ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, Savannah, GA, June 13-18, 2004.
Description:
Voltammetric methods for determination of total sulfide concentrations in anoxic sediments utilizing a previously described [1] gold-based mercury amalgam microelectrode were optimized. Systematic studies in NaCl (supporting electrolyte) and porewater indicate variations in ionic strength do not affect response, whereas an Arrhenius-type temperature response is observed. When voltammetric analyses are carried out with an AIS Systems potentiostat, 90 scans h (-1) are possible with a detection limit of 11 microM (25 s deposition time, cathodic linear sweep) and can be lowered by extending deposition time. Linear range was up to 1 mM in the anodic linear sweep mode. Profiles of steep sulfide gradients in anoxic cores from the Yaquina Bay, OR are presented (to depth of 0.15 m, resolution of 0.001 m) together with an analytical intercomparison of total sulfide concentration profiles in these sediment porewaters. Simultaneous in situ porewater profiles were recorded using two different electrodes; the gold/mercury film microelectrode and an amperometric H2S microelectrode [2]. Subsequent to profiling the sediment porewaters were extracted and analyzed using spectroscopic methods [3]. Results are reported and statistically compared.