| Research Abstract |
For a study to estimate terrigenous air-dust fluxes to oceanic region by using environmental plutonium as a tracer, Pu-239, 240 and Fe were determined in air-dust samples collected in Kanazawa, Japan through the years from 1993 to 1998. The air-dust samples were collected using a five-stages (particle size : <1.1 μm, 1.1〜2.0 μm, 2.0〜3.3 μm, 3.3〜7.0 μm, 7.0 μm<) Andersen-type high-volume air sampler, and catcher plates and backup filter were replaced monthly ; air-dust collected every 1-8 months was analyzed as one batch.
Throughout the above mentioned sampling years and particle sizes, the concentrations of Pu-239, 240 and Fe I n the air-dust samples were in a range from 0.1 to 10 μBq-Pu/mg-dust and from 2 to 30 μg-Fe/mg-dust. The Pu/Fe concentration ratios tend to be high in finer air-dust, suggesting that Pu is adsorbed on the surface of terrigenous air-dust. Through the analyses of Po-210/Pb-210 activity ratios in air-dust samples collected occasionally for a few days using Andersen-type low-volume air sampler, from 9 to 140 days were estimated as the apparent floating time of air-dust (particle size : O.06〜0.13 μm, O.13〜0.22 μm, O.22〜0.33 μm, 0.33〜0.52 μm, 0.52〜0.76 μm, 0.76〜1.3 μm, 1.3〜2.5 μm, 2.5〜3.9 μm, 3.9〜5.7 μm, 5.7〜8.5 μm, 8.5〜12.1 μm).
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