137Cs in glacial meltwater on King George Island, maritime Antarctica

Abstract

Glacierised catchments in maritime Antarctica can retain deposited atmospheric 137Cs and remobilize it during seasonal melting. 137Cs activity was determined in meltwater from 12 glacier outlets on King George Island (South Shetland Islands) during the austral melt season using ammonium phosphomolybdate (AMP) preconcentration and gamma spectrometry. Activities were very low: six outlets were below the detection limit (<0.08-0.09 Bq m−3), whereas detectable values ranged from 0.12 ± 0.07 to 0.37 ± 0.07 Bq m−3. Suspended sediment was recovered from three visibly turbid outlets and analysed separately. Sediment-associated 137Cs was low and heterogeneous among grain-size fractions, with the highest activity measured in the <0.63 mm fraction from Penderecki Glacier (1.21 ± 0.31 Bq kg−1). In sediment-rich outlets, the particulate fraction contributed substantially to total 137Cs activity per unit volume of runoff, indicating that suspended material can act as a local carrier of fallout-derived 137Cs.