Regional-scale application of the decision support system MOIRA-PLUS: an example of assessment of the radiological impact of the Chernobyl accident on the fresh water ecosystem in Italy

The present work illustrates the customisation and application of the decision support system MOIRA-PLUS (a MOdel-based computerised system for management support to Identify optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems and drainage areas) to the fresh water environment in Italy. MOIRA-PLUS is aimed at evaluating the behaviour of radiocaesium and radiostrontium in fresh water ecosystems and at assessing the appropriateness of suitable strategies for the management of contaminated water bodies by the application of multi-attribute analysis techniques. MOIRA-PLUS can be applied to complex networks of lakes, rivers and tributaries and can be straightforwardly customised utilising data and information from readily accessible sources such as official websites provided by scientific or government organisations. The present work shows an application of the decision system to 10 lakes and 18 rivers in Italy contaminated with 137Cs of Chernobyl origin. Site-specific values of some aggregated transfer parameters were estimated for the most important Italian lakes. Although high values of fish and water consumptions were hypothesised, very low doses to public from the fresh water pathway following the accident were calculated.

Research highlights
► MOIRA-PLUS is a computerised decision support system aimed at evaluating the behaviour of radiocaesium and radiostrontium in fresh water ecosystems and at assessing the appropriateness of suitable strategies for the management of the contaminated aquatic environment by the application of advanced multi-attribute analysis techniques.
► MOIRA-PLUS (release 4.1.2) allows the user to customise the migration model for the assessment of the behaviour of radionuclides in complex networks of water systems including, for instance, a main watercourse and several tributaries of different order.
► The test and the calibration of MOIRA-PLUS migration models applied to 18 rivers and 10 lakes in Italy gave the opportunity of customising MOIRA for practical applications to the fresh water environment in the Italian territory.
► The calibrations of the MOIRA-PLUS environmental models offered the opportunity of assessing site-specific values of several migration parameters of importance for predicting the dynamics of radiocaesium in the selected water bodies (radionuclide sedimentation velocity, radionuclide transfer coefficient from catchments, radionuclide burial rate to deep sediment).
► Conclusions: MOIRA-PLUS can be easily customised to complex freshwater systems at regional scale. Information and data obtained from independent empirical studies can be promptly exploited for testing and calibrating the models. MOIRA-PLUS can be used for quick evaluations of radionuclide fluxes through the aquatic compartments and of the doses released to humans.