The relationship between sediment and plutonium budgets in a small macrotidal estuary: Esk estuary, Cumbria, UK

Abstract

During a spring tide, measurements were made of sediment and 239,240Pu discharges through a cross-section of the Esk estuary. These indicated that over the full tidal cycle the inner estuary had a net gain of ca. 18t of sediment and ca. 85 MBq of particulate phase 239,240Pu, and a probable net loss of ca. 1 to 2 MBq of solution phase 239,240Pu. Each of these was the net result of large gross discharges of sediment and plutonium into and out of the estuary for which the sea was the main source, with eroded estuarine sediment providing an additional minor source of sediment, of particulate phase plutonium and, via desorption, of solution phase plutonium. A net input with each tide, of sediment and its associated radionuclides, is considered to be typical for the Esk estuary under the normal conditions of low river flows.