Hot spots identification, sediment management and environmental risk assessment within a gas production field thorough a multidisciplinary approach and a novel expert decision support system

Offshore production of oil and gas involves some of the most advanced and massive engineering projects. Such industrial activities may induce both occasional as well as long lasting environmental impacts in the aquatic ecosystem, often acting in combination with other environmental stressors. Nowadays, complex and advanced multidisciplinary monitoring approaches combining chemical, ecotoxicological and ecological data are available worldwide. These collect large dataset of different information, which need to be correctly inferred and integrated to provide a comprehensive knowledge of the environmental health status. Indeed, a management focused on impacts of a single stressor is inefficient and often ineffective because co-occurring human activities lead to multiple simultaneous impacts on communities and individual species. Thus, a quantitative assessment of the spatial patterns of all human uses of the marine aquatic environment and their cumulative effects is needed for implementing the ecosystem-based management, the ecosystem services conservation and the sustainable exploitation of natural resources processes. In this case study, we apply methods developed to map cumulative impacts in sediments collected during the key steps of the set up and the production phases of a gas platform located in the Adriatic sea. Sampling sites are classified by means of comparing chemical concentrations with effect-based target values. The level of each contaminant and the combined toxic pressure are used to rank sites into uncontaminated, mildly and heavily contaminated. According to a triad based approach, in contaminated sediments, an environmental risk index is determined by means of integrating chemical data with ecotoxicological and ecological parameters. Furthermore, a sediment risk index is computed from combining chemical and ecotoxicological data. At sites identified as moderately contaminated, sub lethal stress index are integrated with chemical data into a biological vulnerability index. In the meantime, potential risk for human health is assessed in selected stations by integrating genotoxicity biomarkers. Finally, geostatistical tools are applied to show the space and time related risk index distribution.