Fugacity/aquivalence modelling framework of contaminant (POPs and heavy metals) fate and transport in the Venice Lagoon

The sediment and water of the Venice Lagoon, mostly those of the industrial canals, have elevated concentrations of persistent organic pollutants (POPs) and trace metals. Present contamination levels in the lagoon are still of concern due to the potential for elevated concentrations in consumable species, namely clams and fish. In order to effectively manage the risk associated with elevated concentrations of contaminants in any system, it is essential to identify their main sources and dominant fate pathways. This paper outlines an integrated modellinq framework developed for POPs and metals in the Venice Lagoon. The framework consists of models for metal speciation-complexation, chemical fate and transport, and POP transfer through the aquatic food web. The fate model uses fugacity-aquivalence as equilibrium criteria suitable for volatile and non-volatile compounds (Diamond et aI., 1992), respectively. For metals, we use TRANSPEC, in which a geochemical model such as MINEQL+, which estimates metal speciation and complexation assuming equilibrium conditions, is loosely coupled to the fate model (Bhavsar et aI., 2004a,b). For POPs, we use a mechanistic food web model (Gewurtz et aI., in press) that uses water and sediment concentrations estimated by the fate model. The framework is mechanistically-based and generally applicable to POPs and metals in a variety of aquatic systems. Here we adapt it to include the hydrodynamic characterization of Solidoro et al. (2004b) and processes unique to the lagoon environment.