Radium in baggerspecie afkomstig uit het Rijnmondgebied. Resultaten over 2001

The radium concentration was measured in 25 samples of harbour sludge taken in 2001 from the Rijnmond area (Rotterdam harbours and the Nieuwe Waterweg). High radium levels were found near the former discharge points of the phosphate ore processing plants, confirming the results of previous campaigns. The highest concentration of about 150 Bq/kg was found in a sample from a section in the Nieuwe Maas (NM-2). The grain-size distribution of the samples was used to estimate the natural radium in the sample and the radium which may be from industrial origin. The average total amount of radium of industrial origin for the 1999-2001 period in the nine regularly probed sections showing the highest radium levels was found to be no more than half of the average for the 1995-1998 period