ИСТИНА

Overbank sedimentation rates on river floodplains provide a key indicator of the intensity of sediment and sediment-associated pollutant redistribution in river basins and the efficiency of sediment delivery. Combined application of the fallout radionuclides 137Cs (bomb-derived and/or Chernobyl-derived) and excess 210Pb provides an effective means of documenting recent medium-term overbank sedimentation rates This approach is particular useful in areas of Europe affected by Chernobyl fallout, because it is frequently possible to determine sedimentation rates for three or more time intervals. In addition, it is possible to use the information on sediment chronology provided to reconstruct the history of industrial and agricultural pollution in the upstream river basin. However, despite the important advantages of fallout radionuclides for establishing overbank sedimentation rates and dating sediment deposits, it is necessary to recognize the possible limitations of the technique, as well as the sampling and sample analysis requirements which need to be considered when documenting and interpreting radionuclide depth distributions. Recently published studies indicate that the requirements for the successful application of fallout radionuclide tracer techniques are unfortunately sometimes ignored, leading to unreliable results or incorrect interpretations. The potential and limitations of fallout radionuclides for investigating overbank sedimentation rates on river floodplains will be reviewed, based on the authors’ own studies as well as other recently published work.