Deposition and accumulation of plutonium isotopes in Antarctica

Abstract

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 contaminants^1–3 and 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 atmosphere^3–6. 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⁻² over 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.