Artificial Radionuclides In Coastal Marine Ecosystems

This chapter presents various models used to predict and study the fate of artificial radionuclides in the coastal marine environment. The two major sources of artificial radionuclides to the environment are from past atmospheric nuclear weapons testing and nuclear facilities, whether civil or military, through controlled or accidental releases. Radionuclides in the ocean are divided into dissolved or particulate forms and are therefore present in both the water column and sediment. Exchanges between these forms are mainly dependent of their physico-chemical properties, and their dispersion is governed by hydrodynamic and hydrosedimentary processes. They are also transferred to living organisms through processes that can be simple such as adsorption and direct absorption from seawater by external surfaces (skin, gills) or more complex via ingestion and subsequent transfer in trophic webs. Several modelling, empirical or mechanistic approaches have been developed since the 1960s to account for and predict the behavior of these contaminants in various equilibrium or dynamic situations. They are presented here, with examples of modelling applications mainly focusing on the Fukushima Daiichi Nuclear Power Plant accident which led to the most important release of artificial radionuclides to the ocean.