ИСТИНА

The radio-cesium technique is a conventional method that has helped shed light on the complexity of erosion, sediment delivery, and aggradation in numerous studies around the world. Although the basic methodology was developed and implemented decades ago, there is potential room for improvement. At least three possible directions of development can be identified. The transformation of radioactive contamination through erosion and accumulation is a continuous and long-lasting process until the complete decay of the selected radionuclide occurs. The examination of radionuclide distributions in the landscape over different time windows provides an opportunity to estimate long-term trends in geomorphic processes and sediment yield formation. Hence repeated depth-incremental sampling and analysis of Chernobyl-derived 137Cs may be instrumental in fluvial geomorphological studies in areas affected by the 1986 fallout. In this regard, each individual study provides a solid foundation for further investigation in the future. Another important aspect of radio-cesium studies is understanding the fate of radionuclides associated with sediment after the fallout event. The migration of pollutants through river systems is not only a serious environmental threat, but it can also be used for sediment budget and fingerprinting studies. The decrease of activity concentration during post-Chernobyl period demonstrates high potential as surrogate of relative age. This finding is consistent with previous research and sheds light on the potential use of 137Cs depth distribution as a proxy of the age during post-Chernobyl accumulation. However, the proposed approach requires a clear understanding of the long-term variation in the radionuclide content in material eroded from slopes and transported into the fluvial system. The improvement of gamma-spectrometry detectors enables more accurate and faster detection of specific radionuclides. Additionally, in-situ measurements are becoming more accessible. Hence, the design of field study may be adjusted to new technical opportunities to obtain a more detailed and representative image of the contamination.