レプリカ作成法を利用した個別雪結晶による粒子洗浄特性解明のための新しい試み A new attempt to study the particle scavenging properties of individual snow crystals using a replication technique.

Access this Article

Author(s)

    • 馬 昌珍 MA Chang-Jin
    • 京都大学大学院エネルギー科学研究科 Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University
    • 笠原 三紀夫 KASAHARA Mikio
    • 京都大学大学院エネルギー科学研究科 Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University
    • 東野 達 TOHNO Susumu
    • 京都大学大学院エネルギー科学研究科 Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University
    • 酒井 卓郎 SAKAI Takuro
    • 日本原子力研究所高崎研究所 Advanced radiation technology center, Japan Atomic Energy Research Institute

Abstract

個別雪結晶の捕集のため, 新しくコロジオン膜を利用し, 雪結晶のレプリカ作成を試みた。雪結晶の捕集は, 2001年1月, 京都大学宇治キャンパスの屋上 (地上約20m) で行った。凝集せず直径120μmから2.5mmまでの六角形と樹枝状のもとの形状を保持した個別雪結晶がコロジオン膜 (130±10μm) 上にレプリカとして捕集できた。化学的内部構造と元素の混合状態を含む個別雪結晶の化学性状特性を調べるため, 荷電粒子励起X線放射 (Particle Induced X-ray Emission, PIXE) 法とmicro-PIXEを応用した。PIXE分析の際, パッキング材の不純物の影響とビーム照射によるコロジオン膜の破損なく, 主に水溶性・不溶性粒子と雪結晶の衝突洗浄効果によって取り込まれた数種類の元素成分を分析することができた。これらの元素の質量は雪結晶の粒径に大きく依存し, 土壌成分と硫黄を含んだ人為起源成分の混合の状態でほとんどが雪結晶の端に分布していることが分かった。本研究から得られた, 個別雪結晶に対する元素質量の粒径依存性, 化学的内部構造と混合状態等の詳細な情報は, 降雪による大気汚染物質の洗浄メカニズムの解明に貢献することができる。

To collect individual snow crystals a particular method for the snow crystal replication was newly applied using collodion (nitrocellulose) film. Samplings of snow crystals were carried out at the Kyoto University Uji Campus during snowfall events in January 2001. Individual snow crystals, which were unagglomerated and maintained their original shapes such as hexagonal and dendritic plates ranged from 120 pm to 2.5 mm, were replicated on thin collodion film (130±10μm). Particle induced X-ray emission (PIXE) and micro-PIXE analytical methods were uniqucly applied to the analysis of individual snow crystals to investigate their particle scavenging properties and chemical characteristics including chemical inner-structure and elemental mixing state. It was possible to resolve the elemental peaks corresponding to channel number of PIXE spectra without filter rupture or film blank concentrations. Several elements, most of which became incorporated into the snow crystals by impaction scavenging of soluble and insoluble aerosol particles, were successfully analyzed. These elemental masses showed the strong size dependence of snow crystal. Almost all of the components were distributed at the rim portion of snow crystals. Every component retained in and/or on individual snow crystals existed as a mixed state of soil and anthropogenic components including sulfur. These detailed results such as the crystal size dependence of elemental mass, chemical inner-structure, and mixed elemental state in individual snow crystals obtained from this study should be helpful to better understand the ice-nucleation and scavenging processes of pollutants by snow.

Journal

  • Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi

    Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi 38(2), 89-99, 2003

    Japan Society for Atmospheric Environment

Codes

Page Top