Ž . The Science of the Total Environment 246 2000 121137 Benthic fluxes of cadmium, lead, copper and nitrogen species in the northern Adriatic Sea in front of the River Po outflow, Italy Cristina Zago a,  , Gabriele Capodaglio a,b , Sergio Ceradini c , Giovanni Ciceri c , Luisa Abelmoschi d , Francesco Soggia d , Paolo Cescon a,b , Giuseppe Scarponi e a Dipartimento Scienze Ambientali, Uni  ersita Ca Foscari di Venezia, Dorsoduro 2137, 30123 Venezia, Italy ` ` b Centro di Studio sulla Chimica e le Tecnologie per l’Ambiente-CNR, Venezia, c  o Uni  ersita Ca Foscari di Venezia, ` ` Dorsoduro 2137, 30123 Venezia, Italy c ENEL, SRI, Via Reggio Emilia 39, 20090 Segrate, Milano, Italy d Dipartimento di Chimica e Chimica Industriale, Sezione Chimica Analitica ed Ambientale, Via Dodecaneso 31, 16146 Geno a, Italy e Instituto di Sciente del mere, Uni  ersita di Ancona, Via Brecce Bianche, 60131 Ancona, Italy ` Received 1 June 1999; accepted 13 October 1999 Abstract Ž . Ž . Trace heavy metal Cd, Pb and Cu and nitrogen species N-NO , N-NO and N-NH fluxes between sediment 3 2 4 and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the River Po outflow. An in situ benthic chamber, equipped with electronic devices for monitoring and adjustment of oxygen and pH and with a temperature detector, was used. The benthic chamber experiment enabled study of the temporal trend of metals and nutrients when oxygen concentration varied in a controlled environment. Although particular care was devoted to chamber deposition and parameter control, sediment resuspension occurred at the beginning of the experiment and O fluctuations were observed during the course of the experiment. Pb 2 concentration was affected by both resuspension and oxic conditions in bottom water, which prevented determination of any reasonable Pb flux value. Cd and Cu, not influenced by oxygen fluctuations, reached an equilibrium phase in a Ž . Ž . 2 1 short period with initial positive fluxes from sediment of 0.68 S.D.0.07 and 6.9 S.D.5.6 pmol cm h , Ž respectively. With regard to nitrogen species, the highest positive flux was that of N-NH 10.5, S.D.2.4, nmol 4 2 1 . Ž cm h whose concentration increased in the chamber, while nitrate concentration initial flux of 5.7, 2 1 . S.D.1.5, nmol cm h immediately decreased after the beginning of the experiment. Nitrite concentration was  Corresponding author. Tel.: 39-0412578504; fax: 39-0412579549. 0048-969700$ - see front matter  2000 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 4 8 - 9 6 9 7 99 00421-0