A quantitative estimate of English Channel water fluxes into the North Sea from 1987 to 1992 based on radiotracer distribution
Résumé
Seven oceanographic campaigns carried out in the North Sea between July 1987 and January 1992 by the Marine Radioecology Laboratory (LRM) of La Hague have led to the drawing of general maps showing the distribution of the radionuclides 125Sb, 137Cs, 134Cs and 99Tc in seawater. In this way, the total amounts of radioactivity (inventories) present in the southern North Sea were evaluated from each separate campaign, thus leading to an assessment of the mean distribution of water masses, originating from the English Channel, which is siutated between the Straits of Dover and Skagerrak. On this basis, it is possible to link the flux of radionuclides released from the nuclear fuel reprocessing plant at La Hague (125Sb and99Tc) with the inventories of radiotracers observed in the southern North Sea. Hence, the most probable mean transit time of Channel waters entering the North Sea were calculated for each campaign; Channel waters take 110–152 days to flow from Cap de la Hague to the Straits of Dover and 170–250 days to travel from there to the entrance of the Baltic. The water flux through the Straits of Dover is estimated to lie in the range 97,000–195,000 m3/s for the period between January and July 1988. Very good agreement is found between the activities measured at different times and the results of a model simulating the hydrodynamic behaviour of the North Sea.
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Bailly_du_Bois_1995_Preprint A quantitative estimate of English Channel water fluxes into the North Sea from 1987 to 1992 based on radiotracer distribution.pdf (3.27 Mo)
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