Investigation of dissolved uranium content in the watershed of Seine River (France)

A systematic survey of dissolved uranium activity was carried out in the Seine and the Marne over one year. A small watershed, the Grand Morin, included in the Seine one, was also investigated from stream to medium-sized rivers. The Melarchez stream exhibits low but variable dissolved U-238 levels (3.3 +/- 2.0 mBq 1(-1)). Thereafter, uranium activities show a rapid increase to reach, from the Grand Morin River, a rather constant range (8-11 mBq 1(-1)). On the Marne before the confluence with the Seine, dissolved U-238 is nearly invariable (9.1 +/- 0.8 mBq 1(-1)), for flow rates comprised between 60 and 423 m(3) s(-1). Dissolved U-238 in the Seine corresponds to almost triple the global mean riverine uranium concentration. In the estuary of the Seine, uranium shows a gradual increase, resulting from conservative mixing of river with sea waters. (C) 2004 Elsevier Ltd. All rights reserved.