Transfer Pathways and Transit Time of Dissolved Matter in the Eastern English Channel Indicated by Space-Time Radiotracers Measurement and Hydrodynamic Modelling

From 1986 to 1989, dissolved artificial radionuclides were used to study the mesoscale transfer of offshore waters from Mid-Channel areas and the Baie de Seine towards the Straits of Dover. The consequences of the Chernobyl accident—as well as the discharges from the nuclear fuel reprocessing plant at La Hague—re utilized in the present investigation. Combined with recent advances in hydrodynamic modelling, the results of this study show that: (a) nearshore waters along the macrotidal eastern Channel coast of France can retain a memory of injected conservative tracers over a period of several months; (b) the transport of dissolved matter between the Mid-Channel and the Straits of Dover occurs with a transit-time of 2-8 months, depending on the type of advection involved (i.e. rapid central, intermediate or slower coastal routes).