Deposition and accumulation of plutonium isotopes in Antarctica

DATA on the deposition of plutonium isotopes are presented here from the atmosphere at Dome C (123°10′E, 74°39′S; 3,214m elevation) on the high Antarctic plateau. Plutonium isotopes are among the anthropogenic chemicals that have become global contaminants1–3and it is, therefore, important to gain a historical perspective to their worldwide dispersion. The analysis of successive layers of permanent snow fields permits the determination of both present and historical fluxes of anthropogenic chemicals and other contaminants that are dispersed through the atmosphere3–6. Dome C is an ideal site for such studies: annual precipitation at Dome C is of the order of 3.7 g H2O cm−2(ref. 7), considerably lower than the mean annual deposition of 15.5 g H2O cm−2over the entire continent8. The mean annual temperature is −53.5 °C7, with summer temperatures remaining well below freezing, precluding vertical percolation through successive layers and reducing potential losses from volatilisation.