The Serchio River catchment, northern Tuscany: Geochemistry of stream waters and sediments, and isotopic composition of dissolved sulfate Gianni Cortecci a, * , Enrico Dinelli b , Tiziano Boschetti c , Paola Arbizzani d , Loredana Pompilio c , Mario Mussi a a Institute of Geosciences and Earth Resources, CNR Research Area, Via Moruzzi 1, I-56124 Pisa, Italy b Interdepartmental Research Centre for Environmental Sciences, Alma Mater Studiorum-University of Bologna, Via Sant’Alberto 163, I-48100 Ravenna, Italy c Department of Earth Sciences, University of Parma, Viale G.P. Usberti 157a, I-43100 Parma, Italy d ECO-TER s.r.l.-Servizi Integrati per Ecologia e Territorio, Via dell’Artignano 27, I-40065 Bologna, Italy Received 13 October 2006; accepted 29 December 2007 Editorial handling by S. Bottrell Available online 9 February 2008 Abstract The Serchio River and its tributaries in northern Tuscany were investigated for the chemical and isotopic compositions of waters and bed sediments. Bedrocks are mostly limestone/dolomite and siliciclastics, thermal spring systems are present in the catchment, and the main industrial activity is represented by paper-mills. Main results obtained are: (1) major ions in solution appear to be basically controlled by precipitation and lithology, as well as subordinately by direct inputs of ther- mal springs, (2) human influence on metals in the waters along the main Serchio and Lima rivers is indicated at a number of sites by increases in concentration compared to the chemical composition of upstream tributaries, (3) S and O isotope compositions delineate two main sources for aqueous SO 2 4 , that is dissolution of Triassic evaporite (directly or via thermal springs) and oxidation of sulfide dispersed in siliciclastic rocks. Anthropogenic contributions are probable, but they cannot be quantitatively assessed. Only SO 2 4 in the notoriously polluted Ozzeri tributary is suspected to be largely anthropogenic, and (4) the chemical composition of bed sediments is mainly influenced by lithology, apart from a number of technogenic elements in the upper part of the Serchio River and in some tributaries. Contamination possibly occurs at other sites, but geochemical indications are weak. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction The knowledge of the distribution and sources of chemical elements in the environment is fundamen- tal for any sound management policy for ecology, drinking water quality, and in general for the well- being of human, animals and plants. This can be achieved by an integrated water-sediment approach, which was applied in the present paper to the Serchio River drainage basin in northern Tuscany, in order to identify natural and anthropogenic 0883-2927/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeochem.2007.12.031 * Corresponding author. Fax: +39 0503152323. E-mail address: g.cortecci@igg.cnr.it (G. Cortecci). Available online at www.sciencedirect.com Applied Geochemistry 23 (2008) 1513–1543 www.elsevier.com/locate/apgeochem Applied Geochemistry