Long-term changes in Chernobyl ¹³⁷Cs inventories in a small agricultural catchment explored from complex resampling...

A resampling campaign was carried out in a small agricultural area within the Chernobyl-affected region of the Central Russian Upland to monitor long-term changes in ¹³⁷Cs contamination and sediment redistribution. Integral soil sampling was carried out on the cultivated slopes, and a depth incremental procedure was used at the bottom of the dry valley. The sampling points ware located in 2024 based on the original study conducted in 1997. The results showed that over the past 27 years, the ¹³⁷Cs inventory at the studied points had increased on average. The most significant changes occurred in the footslope, where surface runoff concentration occurs. The observed increase in ¹³⁷Cs inventory may indicate a bias in the assessment associated with the location of points, primarily along the flow lines, where the intensive intra-slope accumulation occurs, in conditions of a tendency to decrease runoff as a result of snowmelt. The ¹³⁷Cs vertical distribution in sediment redeposited in the dry valley bottom suggests that the sediment and particulate ¹³⁷Cs transfer from cultivated slopes has decreased since the 1990th, but the pattern of accumulation zones remains unchanged. It is argued that complex re-sampling can serve as an effective tool for assessing the current trends in sediment redistribution but faces with serious limitations.