engleski

Solid electrodes for monitoring trace metals in aquatic systems

Environmental metal pollutants deposited at industrial areas or nearby surroundings represent possible threat for the local environment and human health. This is especially the case if former industry areas and surroundings are used as residential areas. Early warning systems, that are stations for monitoring trace metals in aquatic environments is still a challenge since to our best knowledge, no available operational systems can be used in routine. For such measurements, only electrochemical techniques, and more particularly stripping voltammetry may be applied because of: (i) its high sensitivity towards numerous metals such as Cd, Pb, Cu or Zn ; (ii) a relatively small and inexpensive technique ; (iii) no special treatment of the water is required before the measurement. The other techniques used in the laboratory for determining trace metals (mostly ICP-MS and GFAAS) appear indeed inappropiated for on-site measurements. The first and main task to monitor trace metals on-site is the development of solid electrodes or microelectrodes sensitive enough for measuring ppb or even under ppb levels. Mercury drop of film electrodes usually used in laboratory are too toxic and difficult to handle in situ. This presentation is focused on a summary of solid electrodes we have developed during the last 5 years: amalgam electrodes for detecting Pb, Zn, Cd and Fe ; gold microelectrodes of 25 and 125µ ; m for Hg, Zn, Cd, Cu, and Pb and also silver-copper alloy microelectrodes for Zn, Cd and Pb detection. The properties of these electrodes may offer the opportunity to be installed in a monitoring station for trace metal determination in the water column. In addition, the research on microelectrodes should allow us to develop monitoring system of dissolved metals in sediment pore waters. A prototype of monitoring station developed in collaboration with Pr. Ø ; Mikkelsen (NTNU, Norway) is presented. It consists of a voltammetric system, appropriate material for filling and rinsing the cell and stirring the electrode as well. Every part is monitored with a computer and all the system is finally included in a small piece of furniture, which can be easily moved from one place to another. However, current supply is needed, which may be problematic for monitoring on isolated sites.

solid electrodes; trace metals; monitoring; microelectrodes; voltammetry

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