Analysis of radium in sediment samples from the Rhine delta. Results over 1997

Eighteen sediment samples, collected in the harbours and waterways of the Rhine delta in 1997, were analysed for their 226Ra content and grain-size distribution. The effect of the emissions from the phosphate-processing industries on the 226Ra content could be inferred on the basis of these data. As observed in previous monitoring campaigns, the influence of this industry is greatest in and nearby the first and second petroleum harbours. Increases in the 226Ra content of up to 211 Bq/kg were measured in comparison to background levels of 22 to 46 Bq/kg. Approximately 13% of the released 226Ra is deposited in the harbours and waterways. Samples collected once every year were found to reflect the long-term trend in the emissions. 6 refs