The determination of trace metals in estuarine and coastal waters using a voltammetric in situ profiling system

Abstract

This work presents the optimisation, validation and field deployment of a voltammetric in situ profiling (VIP) system for the simultaneous determinations of dynamic Cd(II), Cu(II) and Pb(II) in estuarine and coastal waters. Systematic studies in NaNO 3 (as a supporting electrolyte) and seawater, indicated that variations in ionic strength, pH and dissolved oxygen did not affect the response of the instrument, whereas an Arrhenius type temperature response was observed. The VIP instrument allows the determination of 2-3 samples h 21 , and has a detection limit (defined as 3s) in seawater for Cd(II): 23 pM, Cu(II): 1.13 nM, and Pb(II): 23 pM. The VIP system accurately measured the total dissolved concentrations of Cd(II), Cu(II) and Pb(II) in two certified reference materials; SLRS-3, a river water, and SLEW-2, an estuarine water. Field evaluation of the instrumentation and analytical methods was achieved through a series of surveys in the Plym Estuary (Devon, UK), from which environmental data are presented.

Development and initial deployments of an autonomous in situ instrument for long‐term monitoring of copper (II) in the marine environment

“…For example, the osmosampler (Jannasch et al 1998) and the diffusion gradient in thin film hydrogel technique (Denney et al 1999;Twiss and Moffet 2002) have been used to automate the collection of samples, whereas molecular biosensors (Zeng et al 2003), electrochemical sensors (Wang et al 1995;Tercier et al 1998;Howell et al 2003), and flow-through chemical analyzers with optical detection (Chapin et al 2002, Callahan et al 2004 to trace metal detection, but they have not been shown to function for more than a few days in the field. In addition, many of these sensors suffer from a broad range of interferences, which limits their use in a complex matrix like seawater.…”

Detecting marine hazardous substances and organisms: sensors for pollutants, toxins, and pathogens

“…Several modifications of basic laboratory methodology, including changes in power supply, data acquisition, experimental control, and methods of metal extraction from test samples, are needed, however, to produce a practical, portable polarographic field sensor. Voltammetric instruments are a promising tool for in situ measurements of trace metals (Howell et al, 2003). A commercially available voltammetric in situ profiling system (VIP) (Tercier et al, 1998;Tercier-Waeber et al, 1999) has been successfully applied for autonomous, continuous monitoring in estuarine and coastal marine waters for up to one week (Tercier et al, 1998;Howell et al, 2003) with detection limits for dynamic fractions of Cu(II), Pb(II), Cd(II), and Zn(II) at ppb level, for Mn(II) at ppt level.…”

“…Voltammetric instruments are a promising tool for in situ measurements of trace metals (Howell et al, 2003). A commercially available voltammetric in situ profiling system (VIP) (Tercier et al, 1998;Tercier-Waeber et al, 1999) has been successfully applied for autonomous, continuous monitoring in estuarine and coastal marine waters for up to one week (Tercier et al, 1998;Howell et al, 2003) with detection limits for dynamic fractions of Cu(II), Pb(II), Cd(II), and Zn(II) at ppb level, for Mn(II) at ppt level. Based on the VIP, Tercier-Waeber et al (2005) have presented a Multi Physical-Chemical Profiler (MPCP) employing on gelintegrated voltammetric microsensors and a multi-channel voltammetric probe as well as advanced microprocessor.…”

Temporal variability in dynamic and colloidal metal fractions determined by high resolution in situ measurements in a UK estuary

“…Calibrations were carried out in the laboratory before and after each measurement series (laboratory or in situ) using deoxygenated mixed standards (0.75-2.5 nM Cd and Pb, 3-20 nM Cu) in NaNO 3 (0.1 M). The sensitivity of the signal to changes in pre-concentration time, temperature and ionic strength have been discussed elsewhere (Howell et al, 2003), and appropriate adjustments were made during the quantification of the current peak for each analyte. The adjusted peak height is proportional to the concentration.…”

“…In situ simultaneous measurements of dynamic Cd(II), Cu(II) and Pb(II) species in coastal marine waters using the Voltammetric In situ Profiler (VIP, Idronaut, Milan) system (the term 'dynamic' is defined below) have been reported by, e.g. Howell et al (2003), Tercier-Waeber et al (2005) and Braungardt et al (2009).…”