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(17-11) Speciation of Hg in the Venezia Lagoon using ultra-clean sampling and analysis. Moretto, Ligia*,1, Bloom, Nicolas2, Ugo, Paulo1, 1 University of Venice, Venice, Italy2 Frontier Geosciences Inc., Seattle, WA ABSTRACT- Venezia and its lagoon are one of the cultural wonders of the world and a sensitive marine estuary under stress due to centuries of anthropogenic pollution. Although many studies have dealt with problems related to environmental pollution, little comprehensive research has been undertaken to explore the biogeochemistry of Hg within this fragile ecosystem. This is surprising given that the western side of the lagoon is bordered by the Marghera Industrial zone, which houses many industries that have discharged wastes directly to the lagoon since before world war II. Although many wastes contain Hg, of particular interest is a mercury cell chlor-alkali plant, which operated with little or no pollution control from 1953 to 1985. Since the lagoon is shallow and poorly flushed, contains high sulfate, and high nutrient loadings from agriculture and urban septic tanks, it may act as a vigorous incubator for Hg methylation. We report the findings of a synoptic survey of Hg and methyl Hg in water column and suspended matter samples collected using ultra-clean sampling techniques during November, 2001. Samples were taken in areas ranging from the relatively unimpacted northern lagoon, through the urban waters surrounding Venezia and Murano, and up into the Marghera Industrial zone itself. Samples were collected in the Adriatic Sea, just inside the barrier island of Lido di Venezia (incoming tide) to provide a regional background for comparison. Aqueous total Hg ranged from 1.5 ng/L near Lido to 107 ng/L in the industrial zone, while methyl Hg ranged from <0.01 to 0.13 ng/L. Over the same gradient, suspended total Hg ranged from 500 to 7,000 ng/g, while suspended methyl Hg ranged from 0.5 to 9 ng/g. Key words: methyl, mercury, Venice, lagoon |
