Annali di Chimica, 96, 2006, by Società Chimica Italiana 493 SENIO RIVER ECOSYSTEM: CHARACTERIZATION AND DISTRIBUTION OF INORGANIC SPECIES IN WATER AND SEDIMENTS Dora MELUCCI, 1 Giancarlo TORSI 1 and Clinio LOCATELLI (°)1,2 1 Department of Chemistry “G. Ciamician”, University of Bologna, Via F. Selmi 2, I- 40126 BOLOGNA (Italy) 2 CIRSA (Centro Interdipartimentale di Ricerca per le Scienze Ambientali), Laboratory of Environmental Analytical Chemistry, University of Bologna, Via S. Alberto 163, I-48100 RAVENNA (Italy) Summary – Analytical results are reported for the determination of inorganic species in water and sediments sampled in the Senio river ecosystem. The species determined are Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg, F - , Cl - , Br - , NO 3 - , SO 4 -- , Na + , K + , Ca ++ , Mg ++ , NH 4 + in integrated water, and Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg in sediments. For all the elements, in addition to detection limits, precision and accuracy are given: the former, expressed as relative standard deviation (s r ), and the latter, expressed as relative error (e), were good, being in all cases lower than 6%. Limitedly to Cu, Pb, Cd and Zn a critical comparison with voltammetric measurements is also discussed. INTRODUCTION In the last decades the concentration of toxic substances in the environment continuously increases owing to the anthropic activities. In particular heavy metals have shown to spread very quickly, and for this reason it is felt an increasing necessity of setting up analytical procedures for their determination at trace and ultratrace level 1-5 and especially for their speciation 6-8 in ecosystems which directly concerns the biological functions regarding the man, the fauna and the flora. 9,10 The present paper describes the analytical procedures for the spectroscopic and chromatographic determination of Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg, F - , Cl - , Br - , NO 3 - , SO 4 -- , Na + , K + , Ca ++ , Mg ++ , NH 4 + in integrated water, and Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg in sediments of the Senio river ecosystem. It is important to point out that in the literature there are not reported data pertaining metal concentrations in such an interesting ecosystem, and, for this reason, the present work can be seen also as a first reference point as regards the spatial and temporal chemical characterisation of toxic metals in the Senio river. (°) Corresponding author; e-mail: clinio.locatelli@unibo.it