Geochemistry and radiogenic isotopes of surface waters and suspended solids from the Valdinievole sub-basin (Tuscany, Central Italy)

The Valdinievole sub-basin is located in the western part of the Arno River Basin (Tuscany, Central Italy) and is fed by Nievole, Pescia di Collodi, and Pescia di Pescia rivers as well as by a network of artificial canals that collect urban and industrial wastewaters from a densely inhabited and industrialized area. Nevertheless, these rivers and canals are tributaries of the Padule di Fucecchio, a protected swampy zone that has an important role in the migratory routes of several bird species. The Usciana River reclaims the waters of the Padule di Fucecchio and, after 25 km, it flows into the right bank of the Arno River. The complex ecosystem of the area is characterized by heavy anthropogenic impact such as paper mill industries, flora-nursey farms, thermal spas and one of the most productive Italian tanning districts that make this zone one of the most polluted area of the Arno River Basin. In order to evaluate the anthropogenic and natural contributions in the surface waters and suspended solids, this PhD project is aimed at determining the seasonal variations in terms of main, minor, and trace elements by Ionic Chromatography (IC) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS), respectively. Additionally, Sr and Pb isotopic ratios by Thermal Ionization Mass Spectrometer (TIMS) on water and suspended solid load samples are to be analyzed to discriminate between natural and anthropic sources. Preliminary data have evidenced a relatively wide variability of the main water chemistry, with composition ranging from Ca2+(Mg2+)-HCO3- to Na+-Cl-(SO42-) with concentrations of N-bearing species up to 36 (NO3-), 2.4 (NO2-) and 11.5 (NH4+) mg/L, suggesting, as expected, the strong anthropogenic pressure acting on the Usciana Basin that, inevitably, also reflects into the surface waters of the Arno River.