Analysis of the different source terms of natural radionuclides in a river affected by NORM (Naturally Occurring Radioactive Materials) activities

The present work studied the radioacitivity impact of a coal-fired power plant (CFPP), a NORM industry, on the water of the Regallo river which the plant uses for cooling. Downstream, this river passes through an important irrigated farming area, and it is a tributary of the Ebro, one of Spain’s largest rivers. Although no alteration of the 210Po or 232Th content was detected, the 234,238U and 226Ra contents of the water were significantly greater immediately below CFPP’s discharge point. The 226Ra concentration decreased progressively downstream from the discharge point, but the uranium content increased significantly again at two sampling points 8 km downstream from the CFPP’s effluent. This suggested the presence of another, unexpected uranium source term different from the CFPP. The input from this second uranium source term was even greater than that from the CFPP. Different hypotheses were tested (a reservoir used for irrigation, remobilization from sediments, and the effect of fertilizers used in the area), with it finally being demonstrated that the source was the fertilizers used in the adjacent farming areas.

► An increase of uranium and radium in the water used by a Coal-Fired Power Plant was observed.
► There was an unexpected source of uranium downstream due to fertilizers used in surrounding areas.
► The increase of uranium in the water was correlated with their physico-chemical parameters.