Submersible voltammetric probes for in situ real-time trace element measurements in surface water, groundwater and sediment-water interface

A summary of the state of the art in the development of two submersible vol tammetric probes performed by us to allow continuous, real-time monitoring of trace elements (Cu(II), Pb(II), Cd(II), Zn(II) and Mn(II), Fe(II)) in na tural aquatic ecosystems is given. The first one, called the voltammetric i n situ (VIP) profiling system, allowed in situ measurements in surface wate r and groundwater down to 500 m. Its construction required the development of: (i) a gel-integrated, either single or interconnected, array microsenso r, (ii) a submersible probe and (iii) hardware, firmware and software for c ontrol of the whole system: i.e. data transmission and acquisition, data pr ocessing and maintenance operations. The second system, called the sediment -water interface voltammetric in situ profiling (SIVIP) system, has been de veloped to allow real-time, high spatial resolution trace elements concentr ation profile measurements at the sediment-water interface. Its constructio n required the development of: (i) a gel-integrated microsensor array with 64 individually addressable lines, (ii) a voltammetric probe based on power ful double multiplexing system and single potentiostat allowing simultaneou s measurements over the 64 sensor lines, and (iii) hardware, firmware and s oftware for control of the whole system. A general description of both syst ems as well as examples of laboratory characterization and/or field applica tions are reported.