engleski

Chemical speciation of trace metals in the marine environment by electroanalytical techniques

The fate of released toxic metals in the aquatic systems as well as their bioavailability depend on the chemical form of dissolved trace metals and their reactivity. Physico-chemical characterization of various species of trace metals in the marine environment by electrochemical measurements, at natural concentration levels, is described. Recent results of the ELANI (EUROMAR) Project "Development of Electroanalytical Instrumentation for Physico-Chemical Characterization of Trace Metals in the Marine Environment", are presented. The system uses several different sensing techniques as well as original hardware and software for an automatic determination of different physico-chemical states and reactivity of trace metals. To fulfill the required sensitivity and specificity, basically three modes of electrochemical techniques which are complementary with specific advantages, are on disposal: cathodic stripping voltammetry (CSV), anodic stripping voltammetry (ASV) and potentiometric stripping analysis (PSA). The measuring system is developed combininb special electrochemical cells, working electrodes, system for an efficient stirring of the solution, synchronized with the automatic burettes, pumps, and valves, and supported by specifically developed software that controls the measuring procedure and enables the required data treatment for the speciation of trace metals in the marine environment. The completed automation of polarographic measurements enables routine analysis of seawater samples. The results obtained from pseudopolarograms can be used for: - the species distribution of trace metals (ratio between labile and inert forms) ; - the speciation inside the group of labile complexes ; - the determination of the appropriate deposition potential for metal complexing capacity measurements.

chemical speciation; electroanalytical techniques; electrochemical measurements; aquatic systems

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