The distribution and behaviour of artificial radionuclides in sediments of the north Wales coast,U.K.

The distribution of¹³⁴Cs,¹³⁷Cs and²¹⁴Am in surface and core sediments from areas in north Wales has been investigated. Coastal sites show a predominance of Sellafield-derived material for all three radionuclides whereas estuarine sites show an increased proportion of Chemobyl-derived caesium present. By the use of the¹³⁴Cs/¹³⁷Cs ratio, a mean proportion of Chemobyl-derived¹³⁷Cs in surface sediments collected in 1991 fell from 34% at an estuarine site to 11% at a coastal site. In deeper sections of cores representing sedimentation dates near the Chemobyl accident, up to 90% of¹³⁷Cs at the estuarine site and 26% at the coastal site can be attributed to Chemobyl. By using the position of the Chemobyl¹³⁴Cs and¹³⁷Cs peak in the cores, sedimentation rates of 0.7 mm·a^–1 were calculated.