松葉中のPb-210, Be-7の測定

Abstract

Determination of Be-7 and Pb-210 in pine needles is useful to investigate not only distribution of the radionuclides in the environment but also behavior of air-borne materials in the atmosphere. Radioactivities of Be-7, Pb-210, Cs-137 and K-40 were determined with a well-type Ge detector after pine needles had been to ashes at 450 C. The concentrations of Pb-210 were nearly constant between 2.0 Bq(g-ash)(exp -1) and 2.7 Bq(g-ash)(exp -1), and those of Be-7 ranged from 1.8 Bq(g-ash)(exp -1) to 5.2 Bq(g-ash)(exp -1). Ratios of Be-7 to Pb-210 in pine needles were much smaller than those in rain, This fact leads that the two radionuclides adhered to pine needles for long time, The maximum figure of merit was obtained for 0.8 g-ash of pine needle, corresponding to 40 g of fresh pine needle, by use of a well-type Ge detector.