Man-made radioactivity in the Almanzora Gulch and Beach edge of Palomares, Spain

The 239+240 Pu, 238 Pu and 137 Cs distribution along the Almanzora Gulch and beach edge have been studied. These areas were affected by the accident of 1966, in which a non-nuclear explosion of two thermonuclear bombs occurred. Fluvial sediments at 0-5 cm (in 1990) and 0-10, 10-20, 20-30 cm depth (in 1991) were sampled. The surface inventory (0-5 cm) of radionuclides ranges from 0.4 to 1.8 Bq.m 2 of 239+240 Pu and from 1 to 60 Bq.m 2 of 137 Cs. The estimated total inventory (0-30 cm) shows values from 20 to 264 Bq.m -2 of 239+240 Pu and from 328 to 1147 Bq.m -2 of 137 Cs. The ratio 239+240 Pu/ 137 Cs changes significantly close to the river mouth, probably due to the different behaviour of both radionuclides. At one sampling station a contribution from the Palomares accident was noted based on the ratio 238 Pu/ 239+240 Pu. It seems evident that until no influence from the Chernobyl accident has been detected in this area. The granulometry of the sediments manifests the river hydrodynamics, a dry gulch with periods of floods typical of certain Mediterranean rivers. An important input of terrigenous material containing radionuclides to the adjacent continental shelf occurs in these periods