Deposition of sediments on river floodplains is accompanied by the deposition of sediment-associated nutrients and pollutants Using the ¹³⁷Cs measurement to provide a chronology for sediment cores, in combination with information on downcore variations of the total-P content of floodplain sediment cores, affords a means of investigating recent changes in the total-P content of the suspended sediment deposited on the river floodplains and of documenting recent rates of phosphorus accumulation Results are presented for sediment cores collected from eight floodplain reaches of River Culm, Devon, UK The average values of total-P concentration of fine sediment deposited since 1963 for individual cores range from 0.60 to 1.96 g kg^-1, and the values of total-P storage since 1963 range from 18.6 to 435 g m^-2, showing a trend of total P concentration increasing from upstream to downstream and from the 1960s to the present.