Measurement of atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans in the Lagoon of Venice, Italy

Data on atmospheric fall-out of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were provided by collecting bulk deposition in ofur stations inside the Lagoon of Venice. A total of 44 monthly samples was collected during th epeirod July 1998-July 1999 in one site near an industrial area (Porto Marghera), one site in the city of Venice, and two sites in the southern-and northernmost ends of the lagoon. Fluxes of PCDD/Fs were between 0.1 and 470 pg m to the (minus2) d to the (minus 1), corresponding to 0 - 9.2 pg of 2, 3, 7, 8, - TCDD equivalents (TEQ) m to the (minus2) d to the (minus 1), with a gradient increasing from remote to urban/industrial stations. Thus annual depsotion of PCDD/Fs to the lagoon (total AREA=555 sq km), calculated with various methods, turned out to be about 12 g corresponding to about 400 mg TEQ. Significant differenceswere found among the stations, with a clear fingerprinting signature (PCDF/PCDD greater than 1) of the deposition collected near Porto Marghera, and a reversed pattern (PCDF/PCDD less than 1) in the rest of the lagoon, which pattern was similar to the sediments collected in the same locations. Lastly, the amount of total bulk TEQ of all stations was compared with the guide values for dioxins in depositions proposed by De Fré et al. (Organohalogen Compounds 45 (2000) 324)