The title method was successfully used for collecting Pu-239, Pu-249 from 200 litres of seawater by coprecipitation with 16 g FeSO4 . 7H2O under reducing conditions without filtering. The plutonium is leached by concentrated HNO3 + HCI from the coprecipitate and the solid particles. The precipitate is heated at 400-degrees-C and digested in aqua regia. Na2SO3 and NaNO2 have been applied to obtain the Pu4+ valence state in 0.571 N HN03 for different samples. Plutonium and thorium are coadsorbed on anionic resin from 8N HN03. The column is eluted with 8N HN03 containing fresh NaNO2 to keep the Pu4+ state for uranium decontamination. The system of the column is changed from 8N HNO3 to concentrated HCl with 50 ml concentrated HCI containing a few milligrams of NaNO2. Further decontamination of thorium was achieved by elution with concentrated HCI instead of 9N HCl. The plutonium is successfully stripped by H20, NaOH, 2N HNO3 and 0.5N HNO3 containing 0.01M NaNO3. The chemical yield of plutonium for a 200 l seawater sample is 60-80%. The resolution of the electroplated thin source is very good.