Modelling and assessment of the impact of radiocesium and radiostrontium contamination in the Thermaikos Gulf, Greece G. Eleftheriou a,b, ⁎, L. Monte c , J.E. Brittain d , C. Tsabaris b a Department of Physics, National Technical University of Athens, Greece b Institute of Oceanography, Hellenic Centre for Marine Research, Greece c ENEA, Roma, Italy d Natural History Museum, University of Oslo, Norway HIGHLIGHTS • The Decision Support System (DSS) MOIRA-PLUS was customised to Thermaikos Gulf. • Model results were compared with empirical data to adjust parameter values. • The environmental sensitivity of the Gulf to 90 Sr and 137 Cs pollution was assessed. • Radiation doses from marine and fresh water pathways were compared. • The dose from fresh water pathways is notably higher than that from marine pathways abstract article info Article history: Received 8 March 2015 Received in revised form 20 June 2015 Accepted 24 June 2015 Available online xxxx Editor: D. Barcelo Keywords: Marine environment Radionuclide dispersion modelling Thermaikos Gulf Environmental sensitivity 137 Cs 90 Sr MOIRA-PLUS A radiological model for 137 Cs and 90 Sr dispersion in the marine environment of the Thermaikos Gulf, Greece, and the river catchments draining into the Gulf, is presented. The model, developed and implemented within the MOIRA-PLUS decision support system, integrates appropriate site-specific information. The model's performance has been tested using the available empirical 137 Cs activity concentration data in abiotic and biotic components of the gulf since the Chernobyl accident. Further, this paper describes the results of a modelling exercise performed within the IAEA's EMRAS II international modelling programme to estimate the environmental sensitivity of this characteristic Mediterranean coastal marine environment following radioactive contamination. The radiation doses to humans after a single hypothetical instantaneous deposition of 1000 Bq m -2 , assuming that all of their food intake from the marine pathway comes from the local environment, were calculated. The obtained results are consistent with estimates from other models for different coastal marine environments in the frame of the above-mentioned EMRAS exercise. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The dispersion and the fate of the radionuclides in the marine envi- ronment are of great concern for coastal radioecology and radiation pro- tection. Approaches to the management of the risk in radioecology have to take into account geographic, climatic, living and dietary habits, as well as ecosystem characteristics (Bäverstam et al., 1997; Hisamatsu et al., 2006). Radiological modelling (Scott, 2003) can provide signifi- cant information for the vulnerability of different environments (Håkanson et al., 1996; Tracy et al., 2013) and the environmental sensi- tivity of a particular ecosystem for radioactive contamination can be an important parameter in environmental management and the policy making (Howard, 2000; IAEA, 2001). In radioecology, the analysis of sensitivity focuses on the evaluation of the impact of the release of ra- dioactive substances on the environment and on the human population. In particular, within the frame of the project EMRAS II (Environmental Modeling for Radiation Safety) the analysis of environmental sensitivity to a certain radionuclide was operationally defined as the study of the response to a deposition of 1000 Bq m -2 of the radionuclide over a given region in terms of radionuclide activity concentrations in environ- mental components and of doses to man (IAEA, 2013). The Gulf of Thermaikos, located in the North Aegean Sea, is a typical Mediterranean coastal environment. The coastal zone around Science of the Total Environment 533 (2015) 133–143 ⁎ Corresponding author at: National Technical University of Athens, Dept. of Physics, 9 Heroon Politechniou St., Zografou, 15780 Athens, Greece. E-mail addresses: gelefthe@central.ntua.gr (G. Eleftheriou), monte.luigi@fastwebnet.it (L. Monte). http://dx.doi.org/10.1016/j.scitotenv.2015.06.101 0048-9697/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv