engleski

Redox reactions at sediment/water interface measured by solid Microelectrodes

Voltammetric technique is appropriate for detecting redox reactions, which are often only a part of a complex chemical reaction, but still their characterization can help in understanding of the whole. In the media such as sediment and sediment/water interface, especially if living organisms are present, there is a web of interconnected reactions causing steep speciation and concentration gradients of reactants. Any sampling and ex situ analysis is questionable, so in situ techniques are of utmost importance. Solid microelectrodes are constructed for such a purpose. They are tested on model solutions. Procedures for their preparation and calibration are established and optimized. All the theoretical and practical knowledge about voltammetry as a tool for characterization, speciation and quantification of reactants, done on mercury drop electrodes is available and should be combined with characteristics of microelectrodes to resolve the problems encountered when measuring in situ. Examples of redox reactions measured by cathodic and anodic voltammetry are given, as well as cases of pseudopolarographic curves measured in situ. Reactants that can be measured are O2, HS-, Fe2+, Mn2+ and related species, then heavy metals as Pb2+, Cd2+. Discrepancies between theoretical predictions, models and such in situ obtained results should be explained and quantified. Calibration and comparison with other techniques is envisaged.

solid microelectrode; voltammetry; in situ; sediment; trace metals

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