Gel‐Integrated Voltammetric Microsensors and Submersible Probes as Reliable Tools for Environmental Trace Metal Analysis and Speciation

Abstract

This article gives a review of the analytical and environmental criteria which must be considered and the relevant specific developments needed for direct, reliable voltammetric measurements of trace metal speciation in environmental systems. In particular, this article will focus on the tools which enable remote, long-term in situ measurements. The development of such tools is a challenging task. The strategies that can be used to achieve this goal are described for the development of innovative and versatile gel-integrated voltammetric microsensors, micro-/ mini-integrated analytical systems, and submersible probes. The advantages of these new tools with respect to selectivity, sensitivity, reliability, spatial and temporal resolution of data, and thus efficient environmental monitoring of the biogeochemical cycle of trace metals are demonstrated by providing examples of measurements made in various aquatic samples in laboratory (water, soils, solid -liquid interface) and in situ in fresh and seawaters.

How to overcome inter-electrode variability and instability to quantify dissolved oxygen, Fe(II), mn(II), and S(−II) in undisturbed soils and sediments using voltammetry

“…The pioneering work of Brendel and Luther [11] and Tercier and Buffle [10,12] in the development and use of microelectrodes has enabled in situ voltammetric analysis of redox constituents and trace metals in natural systems [13-17]. While progress has been made and researchers continue to voltammetrically analyze aquatic systems with microelectrodes, there is much room for growth in the number of users and deployments [18]. One impediment to growth is poor understanding of how to convert voltammetric signals to analyte concentrations.…”

Critical review perspective: elemental speciation analysis methods in environmental chemistry - moving towards methodological integration

“…In an estuary, loss of both Pb and Cu was observed at high salinity and could be attributed to adsorption on colloidal or particulate species that were rapidly eliminated from the water column through fast coagulation and sedimentation processes. [53] Strong correlation was found between Cu and chlorophyll a, indicating either assimilation by phytoplankton or complexation by its exudates. However, no such correlation was found for Pb in accordance with the fact that Pb is not easily assimilated.…”

“…Detection of Fe 2+ , H 2 S and molecular FeS clusters at the vicinity of hydrothermal vents indicate that FeS and H 2 S are necessary for pyrite formation. [51] Using a sophisticated submersible flow-through system [52,53] called MPCP (Multi Physical Chemical Profiler), the free metal ion, the electroactivity and the total concentrations of Pb, Cd and Cu were measured down to 150 m depth, together with other physico-chemical parameters (temperature, salinity, turbidity and chlorophyll a). The particulate and colloidal metal concentrations are obtained by subtraction.…”

Dynamic behaviour of trace metals in the Deûle River impacted by recurrent polluted sediment resuspensions: From diel to seasonal evolutions

“…In the 1970s, Zirino et al (1978) developed an automated voltammetric apparatus for on-board measurements with a tubular mercury graphite electrode. More recently, Buffle, Tercier-Waeber and coworkers developed an in situ system based on a gel-covered Hg-plated Ir microelectrodes [for more details, see Tercier-Waeber et al (2008)]. Amalgam electrodes have been used to set up online (Mikkelsen and Schrøder, 2003) or in situ (Luther et al, 2008) analysers.…”