title: Natural and anthropogenic variations in the Po river waters (northern Italy): insights from a multi-isotope approach.
abstract: Po is the main Italian river and the δ(18)O and δ(2)H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca-HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ(13)CDIC and δ(34)SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ(15)NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO(-) 3 concentration. This implies that aquifers' pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.
authors.affiliation: a Department of Physics and Earth Sciences , University of Ferrara , Ferrara , Italy.|b Institute of Life Sciences, Sant'Anna School of Advanced Studies , Pisa , Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Marchina
authors.affiliation: a Department of Physics and Earth Sciences , University of Ferrara , Ferrara , Italy.|c Institute of Geosciences and Earth Resources (IGG), National Research Council (CNR) , Pisa , Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Bianchini
authors.affiliation: d Department Catchment Hydrology , Helmholtz Centre for Environmental Research - UFZ , Halle/Saale , Germany.
authors.forename: Kay
authors.initials: K
authors.lastname: Knoeller
authors.affiliation: a Department of Physics and Earth Sciences , University of Ferrara , Ferrara , Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Natali
authors.affiliation: c Institute of Geosciences and Earth Resources (IGG), National Research Council (CNR) , Pisa , Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Pennisi
authors.affiliation: e Department of Earth Sciences , Sapienza University of Rome , Rome , Italy.
authors.forename: Nicolò
authors.initials: N
authors.lastname: Colombani
mesh_terms: D005618:Fresh Water / Q000737:chemistry*; D007554:Isotopes / Q000032:analysis*; D007558:Italy
chemical_list: D007554:Isotopes
keywords: River/aquifers; carbon-13; hydrogen-2; isotope ecology; isotope geochemistry; isotope hydrology; nitrogen-15; oxygen-18; pollution; sulphur-34