Levels of 137Cs in muddy sediments on the seabed in the Bay of Cádiz (Spain). Part II. Model of vertical migration of 137Cs

This second part of the study reports the development of a model to describe the vertical migration of the artificial radioisotope 137Cs in the sediment column on the seabed of the Bay of Cádiz. The application of the model provides an overall picture of the process of sedimentation in the Inner Bay of Cádiz. The spatial distribution of the rate of sedimentation enables us to study the sources of sediments and the means by which the sediments have been transported. A method has been derived from the rate of sedimentation to perform the dating of the layers of sediment. The model describes the behaviour of 137Cs in the area under study, taking into account the time of residence in the zones that are the source of accumulation, the origin of the sedimentary material, together with the diffusion of the radionuclide in the sediment of the seabed.