title: Influence of UV-B radiation on lead speciation in the presence of natural particles of estuarine waters.
abstract: The influence of UV-B irradiation on filtered and non-filtered water samples collected in a non-polluted area of Tagus estuary was evaluated in this study. In the laboratory, both samples were titrated with lead (Pb(+2)) followed by differential pulse anodic stripping voltammetry (DPASV), before and after 1 and 10 days under UV-B irradiation. Metal-ligand complexing parameters were obtained based on a macromolecular heterogeneous ligand described by two distinct sites with a labile behavior, and a third small homogeneous weaker group, which concentration was determined from a potentiometric titration. Under UV-B radiation, the complexing strength decreased with time in both (filtered and non-filtered) irradiated samples, but this effect was more pronounced in the non-filtered water, which might be due to some adsorption of dissolved macromolecular ligands on the particles and/or to further degradation of dissolved organic matter (DOM). Furthermore, the presence of particles favored the break-down of the macromolecular ligand under long UV-B exposure time. These results present ecological implications for the estuarine ecosystems such as bioavailability and toxicity.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal. praveen.mallupattu@gmail.com.
authors.forename: M Praveen
authors.initials: MP
authors.lastname: Kumar
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: A M
authors.initials: AM
authors.lastname: Mota
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: M L S
authors.initials: ML
authors.lastname: Gonçalves
mesh_terms: D000327:Adsorption; D063366:Estuaries; D007854:Lead / Q000032:analysis*; D008024:Ligands; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008024:Ligands; D014874:Water Pollutants, Chemical; D014867:Water; D007854:Lead
keywords: DPASV; Lead speciation; Particles; Portugal; Tagus estuary; UV-B radiation