Electrochemical detection of commercial silver nanoparticles: identification, sizing and detection in environmental media.

The electrochemistry of silver nanoparticles contained in a consumer product has been studied. The redox properties of silver particles in a commercially available disinfectant cleaning spray were investigated via cyclic voltammetry before particle-impact voltammetry was used to detect single particles in both a typical aqueous electrolyte and authentic seawater media. We show that particle-impact voltammetry is a promising method for the detection of nanoparticles that have leached into the environment from consumer products, which is an important development for the determination of risks associated with the incorporation of nanotechnology into everyday products.

Dynamics and fates of trace metals chronically input in a Mediterranean coastal zone impacted by a large urban area.

Quantification and characterization of chronic inputs of trace metals and organic carbon in a coastal Mediterranean area (the city of Marseille) during the dry season was carried out. The 625 km(2) watershed includes two small coastal rivers whose waters are mixed with treated wastewater (TWW) just before their outlet into the sea. Dissolved and particulate Cu, Pb, Cd, Zn, Co, Ni and organic carbon concentrations in the rivers were comparable to those in other Mediterranean coastal areas, whereas at the outlet, 2- to 18-fold higher concentrations reflected the impact of the TWW. A non-conservative behavior observed for most of the studied metals in the mixing zone was validated by a remobilization experiment performed in the laboratory. The results showed that sorption/desorption processes could occur with slow kinetics with respect to the mixing time in the plume, indicating non-equilibrium in the dissolved/particulate metal distribution. Thus, a sample filtration immediately after sampling is strictly required.

Distribution and chemical speciation of arsenic and heavy metals in highly contaminated waters used for health care purposes (Srebrenica, Bosnia and Herzegovina).

Determination of distribution and chemical speciation of arsenic and heavy metals in five acidic springs and in the receiving river near Srebrenica (Bosnia and Herzegovina) was carried out. These waters were used for centuries, and continue to be used, for health-care purposes. The composition and properties of all springs and the river water (after all inputs) resembled that of an acid mine drainage. Very low pH (<3.3), high sulphate concentration and extremely high contents of most of the measured elements (25) are found in all springs (e.g. arsenic and iron maximal concentration of 6.6 and 500 mg L(-1), respectively). Although of small discharge, spring waters caused the decrease of the receiving river pH (from 7.3 to 3.4) and the considerable increase of the concentrations of elements. The enrichment factor for the studied elements ranged from 1.2 for Sr up to 425 for As. In acidic spring waters, all elements were predominantly present in dissolved form. Elements associated to freshly-formed hydrous ferric oxide were prevailing in particulate forms only at the two most upstream sites in the river with pH>7. Geochemical speciation modelling (PHREEQC and WHAM-VI) revealed that As was mainly present as As(V), and Fe as Fe(III). Complexation of dissolved metals by organic matter was predicted to be significant only for the two river sites with neutral pH.