Americium in the Finnish environment

This paper reviews studies on environmental americium, 241 Am, in Finland.There are two sources of americium in the Finnish environment: fallouts from nuclear weapons tests in the 1950s and 1960s and from the Chernobyl accident in 1986, the former constituting around 98% of the total environmental load.The weapons test fallout was distributed more or less uniformly over Finland, while the Chernobyl fallout was deposited on a sector from southwestern coast to northeast.The total deposition of 241 Am in Finland is approximately 20 Bq m -2 and the amount is still somewhat increasing due to decay of 241 Pu.In this paper, the distribution and migration of americium in forest and aquatic environments is described.Americium concentrations in natural waters, sediments, soils, vegetation and fishes are given.In addition, the behaviour of americium in the food chain from lichen via reindeer into man is discussed.Radiation doses to humans due to the environmental americium in Finland are of no practical importance.