Long-term variation of radiocaesium in the food chain of lamb in the Faroe Islands

Radiocaesium has been measured in the food chain of lamb for eight years in nine uncultivated pastures in the Faroe Islands. Soil, grass and lamb meat were studied in 1990–1997, and lamb faeces in 1995–1997. The deposition is attributable to weapon tests and the Chernobyl accident with the largest proportion deriving from the weapon tests. The deposition in the top 10 cm of the soil was 3–8 kBq/m2, and a significant decrease with time was noted for only one pasture. Effective ecological half-lives of 137Cs concentration in grass and lamb meat could be estimated for some pastures (2.0–11.4 years for grass and 4.0–12.6 years for meat). The observed activities and transfer estimates of 137Cs vary significantly between as well as within the pastures. Chemical characteristics of the soil and precipitation rates in the pastures were considered in connection with the observations.