Storm water pollution in the urban environment of Genoa, Italy I. Gnecco T , C. Berretta, L.G. Lanza,P.La Barbera Department of Environmental Engineering, University of Genoa, Via Montallegro 1, 16145 Genova, Italy Received 1 May 2004; received in revised form 17 September 2004; accepted 15 October 2004 Abstract Nonpoint pollution resulting from urban surface runoff is recognized as one of the major c of quality deterioration in the receiving water bodies.In orderto investigate the first flush phenomenon connected to different types ofurban surfaces, two monitoring systems have been installed in the experimental catchment of Villa Cambiaso, University of Genoa (Italy), to sample separately roof and road runoff. In the monitoring campaign, which has been held since January 2002 in the town of Genoa, the following parameters have been investigated: total suspend COD, NH 4 + , pH and heavy metals in dissolved form (Zn, Pb, Cu, Cd, Cr, Ni). As for road runoff, and COD concentration values exceed water quality standards, while the concentration of zinc is relevant in roof runoff. A strong correlation is observed between COD and TSS concentration Event Mean Concentration (EMC) of various pollutants in road runoff is comparable to the ty values observed in residential areas, according to the American and European studies repor literature. Two dimensionless representations of the wash-off process are provided for TSS a based on the cumulative pollutant mass and the Partial EventMean Concentration (PEMC). First flush of suspended solids is observed in more than 70% of the monitored rainfall events. Re roofrunoff,the magnitude of first flush forheavy metals in dissolved form is affected by both rainfallcharacteristics (intensity and total depth)and the antecedent environmental conditions. Simple correlations between rainfall characteristics (average and maximum rainfall intensity, total rainfall depth, total runoff volume, maximum runoff discharge, antecedent dry weather peri 0169-8095/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.atmosres.2004.10.017 T Corresponding author. Tel.: +39 010 353 2301; fax: +39 010 353 2481. E-mail address: ignecco@diam.unige.it (I. Gnecco). Atmospheric Research 77 (2005) 60 – 73 www.elsevier.com/locate/atmos