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The aim of this work is the development of a procedure for the determination of aqueous Hg(II) by anodic stripping voltammetry at a gold nanoparticle-modified glassy carbon electrode (AuNPs-GCE). The signal of aqueous Hg(II) was measured in the square wave mode; the effect of potential scan parameters, deposition potential and deposition time on the analytical signal was examined. The supporting electrolyte was 0.06 M HCl. The repeatability, the linearity, the accuracy, the detection limit of the procedure and the interferences of other cations and of anions were evaluated. The performance of the AuNPs-GCE was compared with those of a solid (SGE) and a film (FGE) gold electrode: the AuNPs-GCE showed to provide lower detection limits and higher repeatability. The renewable surface permits to eliminate memory effects, to maintain a stable baseline and response, and to avoid frequent mechanical cleaning steps. The applicability of the AuNPs-GCE for Hg(II) determination in drinking waters, sediments and pharmaceuticals was demonstrated.

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We evaluated the distribution of 15 metal ions, namely Al, Cd, Cu, Cr, Fe, La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr, in the soil of a contaminated site in Piedmont (Italy). This area was found to be heavily contaminated with Cu, Cr and Ni. The availability of these metal ions was studied using Tessier's sequential extraction procedure: the fraction of mobile species, which potentially is the most harmful for the environment, was much higher than that normally present in unpolluted soils.This soil was hence used to evaluate the effectiveness of treatment with vermiculite to reduce the availability of the pollutants to two plants, Lactuca sativa and Spinacia oleracea, by pot experiments. The results indicated that the addition of vermiculite significantly reduces the uptake of metal pollutants by plants, confirming the possibility of using this clay in amendment treatments of metal-contaminated soils. The effect of plant growth on metal fractionation in soils was investigated. Finally, the sum of the metal percentages extracted into the first two fractions of Tessier's protocol was found to be suitable in predicting the phytoavailability of most of the pollutants present in the investigated soil.

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A contaminated soil from Pieve Vergonte (Piedmont, Italy) has been investigated in order to point out the availability and extractability of a series of metal ions and consequently their potential release into other environmental compartments. A sequential extraction procedure has been adopted in order to subdivide total concentrations into five operational fractions with different potential toxicity. A chemometric analysis has been used for the characterization of similarities or differences of behaviour.High concentrations of the main pollutants, namely Cu, Pb and Zn, were extracted into the exchangeable, carbonate-bound/specifically adsorbed and Fe-Mn oxide bound fractions, showing the risk of release of these metals into the environment.A remobilization of Cr, Mn and Ni could also take place, but to a lesser extent. The other investigated metals (Al, Fe, La, Sc, V, Ti and Y) were mainly bound to the residual and, in some samples, to the Fe-Mn oxide bound fractions.The high availability of several potentially toxic metals shows that the soil needs remediation.

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