A tracer study of the transport of coastal water from the English Channel through the German Bight to the Kattegat

Abstract

The transport of coastal water from the English Channel along the French, Belgian, Netherlands, German and Danish coasts into the Kattegat has been studied utilizing a conservative radioactive tracer, 99 Tc, discharged from the nuclear fuel reprocessing plant at La Hague in northwest France. It is estimated that ~ 10% of the la Hague (English Channel) discharge and ~ 2% of the Sellafield (Irish Sea) discharge is transferred to the Kattegat. The high proportion of La Hague discharges in the Kattegat indicates the effect of long distance coastal water transport on the pollutant balance in interior Danish waters. It is probable that contaminant discharges to the coastal current occurring closer to Denmark than La Hague are transported to the Kattegat in greater proportions than 10%. It is concluded, that the rare radionuclide 99 Tc is an extremely valuable tracer for inflow of European coastal water to the Kattegat, as the tracer results add a genuine supplement to existing knowledge based on classical oceanographic data.