Uranium contents in raw waters from Biscay (Spain)

The determination of 234U, 238U and 235U in raw waters (surface waters) from four treatment plants located in northern Spain has given mean values of 2.52 mBq/l for 234U, 1.77 mBq/l for 238U and 0.11 mBq/l for 235U. The activity concentration is higher in summer than in winter. The knowledge of the uranium contents in waters in the previous and later instants of its treatment allows the determination of the removal percentage of uranium, whose mean value is 61.3%.