ADIOS is a focussed pan-European study of the atmospheric deposition and impact of pollutants, key elements and nutrients on the Mediterranean open sea. The extent to which atmosphere represents an important pathway for various pollutants and natural substances from Europe and North Africa towards this ecologically sensitive marine environment, and subsequently affects its biogeochemistry remains largely unknown. The magnitude and quality of atmospheric deposition will be assessed by an atmospheric sampling network encompassing the whole basin, as well as by the extensive use of Sea WIFS data and dust transport-deposition modelling. Biogeochemical processes, levels and ecotoxicological effects induced by natural and anthropogenic aerosols will be examined, from surface down to the deep sediments, in two central sites of the Eastern and Western basins, using oceanographic surveys, moored instrumentation and 3D ecohydro dynamical modelling.
The actual outcome of the project can be summarised in the following way, with respect to the initial objectives:
1. Remote sensing and modelling of atmospheric inputs: better characterisation of natural and anthropogenic inputs at the scale of the entire Mediterranean basin; improved dust load maps and atmospheric transfer-deposition models; improved integration between the two complementary approaches;
2. Sampling and chemical characterisation of atmospheric inputs: better quantification and chemical characterisation of the levels and variability of atmospheric inputs of pollutants, key elements and nutrients over the entire basin; improved ground truth/remotely-sensed data relations;
3. Biogeochemical response of the open Mediterranean environment to atmospheric inputs: better understanding of effects nutrients on the biogeochemical processes of the open Mediterranean ecosystem in response to natural deposition events; increasing knowledge of pollutants impact and nutrients bioavailability; model outputs to assess atmospheric influence on N and P budgets under different input scenarios;
4. Transfer of pollutants and key elements through the water column: quantification of open ocean SPM and downward fluxes of pollutants and key elements; better understanding of the respective role of atmospheric and continental margin derived material in the transfer of key elements and pollutants towards the deep environment; model ouputs of pollutant transfer;
5. Accumulation and impact of pollutants and key elements in the deep benthic compartment: quantification of pollutant concentrations, inventories and historical fluxes to the deep Mediterranean sea floor; pollutant ecotoxicological impact on benthic biota. The various achievements of the project represent, first, a scientific innovation by the fact that the project was an integrated, multidisciplinary effort that took into account, for the first time in its entirety, the open Mediterraenan system, an almost terra incognita regarding ecosystem response to atmospheric deposition. Indeed, the most outstanding efforts developed by previous projects addressed the processes and effects of atmospheric deposition in a fragmented approach, were restricted to coastal Mediterranean areas and only considered a limited number of pollutants or specific processes. By addressing the distribution and fate of a coherent set of representative pollutants, key elements and nutrients within the different compartments of the marine ecosystem, from the atmosphere down to the deep sediments, ADIOS provides new data that largely extend our knowledge beyond the previous state. This includes now the effects induced by these substances on the biology and biogeochemistry of the marine ecosystem, and their ecotoxicological impact on the deep Mediterraenan biota.

The project also represents a significant strategic innovation due to the simultaneous implementation of complementary approaches to the problem of atmospheric deposition in the Mediterranean Sea: dedicated atmospheric and oceanic sampling networks, field cruises, remote sensing, modelling, laboratory experiments. Identical atmospheric stations were installed for the first time all over the Mediterranean basin, including northern Africa. They were set-up and run with the same methodologies and principles, allowing comparable basin-scale data sets. To determine the effects of these inputs, two experimental sites were defined in the centre of the Eastern and Western Mediterranean, in the most central area of each basin, supposedly clear of major interference from continental run-off. These sites were instrumented to an unprecedented level (a total of 6 mooring lines with 22 sediment trap-current meter pairs) and worked for a period of one year. Seasonal surveys of the water column were performed. Sediments were analysed to assess present and past (pre-industrial) status of contamination. Last, the effects triggered by a strong atmospheric input were studied through a dedicated "Fast Response Experiment". Third, methodological innovation was provided by the integration of numerical models into the workplan structure. Simulations were no longer considered as per se research activities. Instead, they have been integrated at various levels to attack realistic multidisciplinary problems. Several other methodological innovations were further implemented. Deposition events were determined and categorised using satellite technology (SeaWiFS), meteorological modelling, and field sampling. This allowed an extensive, still underway intercomparison of the different methods and, thus, their improvement. Models for atmospheric dust and particle transport in the sea were also improved and coupled to provide a better understanding on the impact of dust deposition on the water surface and subsequent dispersion in the water column.