Atmospheric input of organic pollutants to the Venice Lagoon

The atmospheric deposition of dioxins and furans (PCDD-Fs), dioxin-like pol ychlorobyphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and hexach lorobenzene (HCB) was determined in the Lagoon of Venice. Sampling was carr ied out monthly, for a total of 13 months (July 1998-July 1999) using "bulk " samplers (passive collectors of wet and dry depositions) at four sites, i nside the lagoon and close to its edge. Calculated PCDD-F loadings to the L agoon turned out to be quite homogeneous, their range being similar to 10-2 0 ng m(-2) y(-1), whereas in the station located close to the industrial zo ne of Porto Marghera the value was similar to 50 ng m(-2) y(-1). PCB deposi tion. in the industrial fallout sampling site and in the city centre of Ven ice was similar to 2500 ng m(-2) y(-1), that is, almost five times higher t han the values measured at the northern and southern lagoon stations. HCB a nnual loading (similar to 8000 ng m(-2) y(-1)) was almost six times higher in the industrial zone than in the other sites (similar to 1500 ng M-2 y(-1 )). PAH loadings in the city centre of Venice and at Porto Marghera were 31 4 and 389 mug m(-2) y(-1), respectively. The amount of 2,3,7,8-TCDD equival ents (TEQ) of PCDD-Fs and PCBs in the Venice and Porto Marghera bulk deposi tions was compared with the guideline value of 15 pg m(-2) d(-1) for dioxin s in depositions proposed by De Fre et al. (1998). Moreover, as some of the effects which drive the risk assessment of dioxin-like compounds were also observed after exposure to other molecules, the TEQs of PAHs and HCB were also calculated: nine out of 13 samples exceeded the guideline value. Lastl y, an atmospheric emission source related to vinyl chloride monomer product ion, which may affect atmospheric deposition on the whole Lagoon, is report ed in the industrial zone of Porto Marghera.