Assessment of spatial variation of cesium-137 in small catchments

Surface contamination by bomb-derived and Chernobyl-derived137Cs has been subject to changes due to physical decay and lateral transport of contaminated soil particles, which have resulted in an ongoing transfer of radionuclides from terrestrial ecosystems to surface water, river bed sediments, and flood plains. Knowledge of the different sources of spatial variation of137Cs is particularly essential for estimating137Cs transfer to fluvial systems and for successfully applying137Cs as an environmental tracer in soil erosion studies. This study combined a straightforward sediment redistribution model and geostatistical interpolation of point samples of137Cs activities in soil to distinguish the effects of sediment erosion and deposition from other sources of variation in137Cs in the small Mochovce catchment in Slovakia. These other sources of variation could then be interpreted. Besides erosion and deposition processes, the initial pattern of137Cs deposition, floodplain sedimentation, and short-range spatial variation were identified as the major sources of spatial variation of the137Cs inventory.