Investigation into the radioactivity of surface waters in the Netherlands

This report over 1989 summarizes the results of the determination of radioactivity in the rivers Meuse, Rhine, Roer, Westerscheldt and the channel of Sas van Gent to Terneuzen at locations near the border, as well as the Westerscheldt at Hansweert and Vlissingen and the North Sea at some locations along the Dutch coast. Concentrations of 90Sr in the Meuse, Rhine and Roer (3.0 up to 4.1Bq/m3) and in the Westerscheldt (9 Bq/m3) were equal to, and in the North Sea ( up to 17 Bq/m3) generally higher then the levels during 1988. The latter are caused by discharges of installations processing used nuclear fuel. The concentrations in the Westerscheldt are partly explained by mixing with water from the North Sea. Concentrations of 89Sr in the Meuse, Rhine and Roer were below the limit of detection. In 1989 concentrations of 226Ra in the rivers Rhine (4.2 Bq/m3), Roer (15 Bq/m3) and Westerscheldt (38Bq/m3) were a bit higher than in 1988. Those of the Meuse (3.3 Bq/m3) were unchanged. The relatively high concentration in the Roer can be explained by liquid discharges of coalmines in the FRG while the one in the Westerscheldt originates from discharges by plants processing phosphate rock. The amount of 226Ra transported in 1988 by the river Westerscheldt was approximately 200 GBq. In the Westerscheldt the concentrations of 210Pb (16 Bq/m3) and of 210Po (19 Bq/m3) clearly exceeds those in the rivers Meuse, Rhine and Roer (2 to 5 Bq/m3), due to discharges of phosphogypsum. Also the 210Pb level in the channel of Sas van Gent to Terneuzen (6.8 Bq/m3) was a bit higher. Concentrations of 3H in the North Sea varied between 2200Bq/m3 for the location Walcheren (20 km out of the coast) down to 1300 Bq/m3 for the location Terschelling (100 km out of the coast). A level of 22 Bq/m3137Cs in the North Sea has been measured at Terschelling. At the other locations the levels ranged from 7 to 9 Bq/m3. 134Cs levels were below the limit of detection. (author). 5 refs.; 6 figs.; 13 tabs