Storage and distribution of plutonium, 241Am, 137Cs and 210Pbxs in North Sea sediments

The net storage of the radionuclides 238Pu (2.8 TBq), 239, 240Pu (75 TBq), 137Cs (730 TBq), 241Am (40 TBq) and 210Pbxs (2700 TBq) in North Sea sediments has been estimated from their concentrations in 40 boxcores. From comparison of 238Pu/239, 240Pu ratios between those found in the sediments and those in atmospheric fallout and discharges from the nuclear fuel reprocessing plants at Sellafield (UK) and la Hague (France), it is concluded that the latter is the main supplier of plutonium to the Southern Bight, while the former is dominant in the remainder of the North Sea. About 7% of all Sellafield plutonium discharge is stored in North Sea sediments. The German Bight receives and stores plutonium and fine particulate matter mainly from the Elbe estuary. Of all 137Cs transported through the North Sea, about 2% is stored in the sediment. 241Am is scavenged faster than plutonium and is probably transported from Sellafield to the North Sea as 241Pu.