[en] This thesis describes a study of the distribution and behaviour of natural and manmade radionuclides in the intertidal environment of south west Scotland. This work is particularly concerned with transport processes affecting radionuclides and with the application of radionuclides as tracers of natural environmental processes. Results are presented for study sites at Ardmore Bay in the Clyde Sea Area and Skyreburn Bay, Wigtown Martyr's Stake and Netherclifton in the Solway Firth with the radionuclides investigated being ¹³⁴Cs, ¹³⁷Cs, ²¹⁰Pb, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, ²³⁸U, ²³²Th and ²³⁰Th. The study confirms and extends an existing model for particle associated Sellafield waste radionuclide transport to the intertidal areas of the Solway Firth and the work, moreover, establishes that the same supply mechanism operates in the floodplain, or merse, areas of the Solway Firth. Inventories of the order of 10⁵, 10⁴ and 10⁴ Bq m^-2 are derived for ¹³⁷Cs, ²⁴¹Am and ^239,240Pu respectively in the merse sediments, indicating inventories for these nuclides of the order of 7, 1 and 1 TBq in the total area of the merse deposits of the Solway Firth. A description is provided of a study of uranium movement through the Solway floodplain silts in the vicinity of a uranium mineralization vein and it is established that uranium migration for distances of up to 55 m can be observed with continuous removal from solution during transport by uptake by iron/manganese oxides and organic materials. The removal process is characterised by a 10 m halving distance. The radionuclide data are considered in the context of tracer studies of various environmental processes including large scale sediment movement in the Irish Sea, local sediment movement in particular bays and, at individual sites, mixing and accumulating processes. (author)