Studies on plutonium in terrigenous air-dust

为了利用环境钚作为示踪剂估计陆源空气粉尘对海洋的通量，对1993 ~ 1998年在日本金泽采集的空气粉尘样品中的Pu-239、240和Fe进行了测定。采用5级（粒径<1.1 μm、1.1 ~ 2.0 μm、2.0 ~ 3.3 μm、3.3 ~ 7.0 μm、7.0 μm<）安徒生式大容量空气采样器采集空气粉尘样品，每月更换捕集板和备用过滤器；每1-8个月收集一次的空气粉尘作为一个批次进行分析。在上述采样年份和粒径范围内，空气粉尘样品中Pu-239、240和Fe - I的浓度分别在0.1 ~ 10 μBq-Pu/mg-dust和2 ~ 30 μg-Fe/mg-dust之间。在较细的空气粉尘中，Pu/Fe浓度比趋于较高，表明Pu被吸附在陆源空气粉尘表面。通过分析po - 210 / pb - 210活性比air-dust样本收集偶尔几天使用Andersen-type少量空气取样器,从9到140天的明显的浮动时间估计air-dust(颗粒大小:O.06 ~ 0.13μm, O.13 ~ 0.22μm, O.22 ~ 0.33μm, 0.33 ~ 0.52μm, 0.52 ~ 0.76μm, 0.76 ~ 1.3μm, 1.3 ~ 2.5μm, 2.5 ~ 3.9μm, 3.9 ~ 5.7μm, 5.7 ~ 8.5μm, 8.5 ~ 12.1μm)。

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).