Interpreting the Cs-137 profiles observed in several small lakes and reservoirs in southern England

The depth distribution of bomb-derived Cs-137 has been studied in cores collected from five small lakes and reservoirs with high sediment accumulation rates in southern England. An empirical approach was employed to demonstrate the Cs-137 input and the post-depositional redistribution of Cs-137 On the (CS)-C-137 profiles of the influence of the catchment-derived sediment cores. By incorporating the remobilisation of Cs-137 and deposited sediment, a catchment-related Cs-137 lake deposition model has been used to interpret the Cs-137 inventories and concentrations in the lake and reservoir sediments in terms of sediment sources. A clear linkage between the Cs-137 concentration in the lake sediment and that in catchment source soils has been established for the five water bodies. Estimates of the proportion of the total Cs-137 inventory of individual sediment cores derived from the catchments ranged between 57% and 97%. These values emphasise the importance of the catchment-derived contribution to the overall Cs inventory of sediments in small lakes and reservoirs receiving significant sediment inputs from their catchments. The estimates of sedimentation rates for the water bodies provided by the cores were also used to estimate the sediment yields from their respective catchments.