Potentially toxic elements, biogeochemical and isotopic markers as environmental quality indicators in a complex land system (Ravenna, Italy)

The final conclusions of a multidisciplinary study of Earth and Soil Sciences, carried out in the frame of Prin 2007 are presented. The study has dealt with a variety of natural materials, encompassing soils, waters, atmospheric depositions, the vegetation and the bottom sediments of a coastal lagoon, in the territory north of Ravenna, characterized by important agricultural and industrial activities. In particular, by chemical and isotopic methodologies and pedological survey, it has been studied the ecosystem of the San Vitale Pinewood and the Lagoon of Pialassa Baiona, both constituting the southernmost part of the Po river delta Park. The results obtained have shown that the Pinewood is affected by major salinization processes induced by local subsidence and concerning underground water and soils. This jeopardizes the vegetation's health, in particular, the pine trees that are the main characteristic species. Moreover, the proximity of the industrial zone of Ravenna to the Pinewood represents another threat to the environment, as it is a major pollution source by release of particulate matter with stacks. Therefore, potentially toxic elements may fallout onto the soils, waters and vegetation of the Pinewood, arising general concern on the preservation of the forest. The important traffic rolling on the road net contouring the Pinewood-Lagoon ecosystem is a further source of pollution, as indicated by the incoming diffusion of PGE on the topsoils bordering the roads. Lastly, the study of the bottom deposits of the Lagoon at the water-sediment interface has unveiled the diffuse presence of Hg with significant concentrations, derived from industrial wastewaters unloaded in the basin some decades ago. Luckily, Hg occurs in the element form and, thus, its mobility is very reduced, keeping so far the risk factor in the Lagoon low. As a whole, the Pinewood-Lagoon ecosystem is ailing due to incoming salinization processes and, subordinately, moderate pollution proceeding from the industrial zone and the traffic. Therefore, it is recommended to implement a monitoring survey of the study area on the ground of the parameters used in this research. In fact, they have been able to provide the local Administrations with punctual responses to the problem of degradation of the Pinewood-Lagoon ecosystem.