WDXRFによる樹氷と雪の中の非水溶性イオウ化合物の化学形態別分析と東アジアの石炭燃焼排出物の冬期モンスーン下での長距離輸送機構

　樹氷と雪の中の非水溶性イオウ化合物の化学形態別分析と東アジアの石炭燃焼排出物の冬期モンスーン下での長距離輸送機構の同定法についてまとめた．単一分光結晶を用いた波長分散型蛍光エックス線装置による樹氷や雪の濾過物であるメンブレンフィルター上の薄膜分析を行った．S-Kα 線の化学シフトからイオウの化学状態別分析が可能であった．樹氷と雪の試料に限ってはカルシウム濃度とイオウ濃度からも化学状態分析が可能であった．卓上型の低真空走査電子顕微境エネルギー分散型X 線分光法（SEM-EDX）を用いて濾過薄膜中の無機小球体粒子（主に石炭フライアッシュ）の一粒子分析を行った．レーダーチャートパターンから5 種類のカテゴリーが見つかり，かつ，24 h 後方流跡線から発生域を中国華北，北東中国，朝鮮半島，黒竜江省－ロシア沿海地方，および日本を発生域に特定することを提案した．溶存成分中のCd，Pb，非海塩性硫酸イオンのモル比からそれらの発生域を特定できることもわかった．これらは，中国炭のイオウ同位体比，日本における鉛同位体比からの地域分けと一致した．

We have conducted the analysis of chemical species of water-insoluble sulfur compounds in rime ice and snow and used the analysis to propose a long-range transport mechanism for coal-burning emissions in East Asia under winter monsoon conditions. Thin films of insoluble substances included in rime ice and snow on a 0.45 μm pore size membrane filter were analyzed by wavelength-dispersive X-ray fluorescence spectrometry with single dispersive crystal. Using this approach, we could analyze the sulfur-containing chemical species by examining the chemical shift of the S-Kα line. The chemical species containing sulfur were analyzed exclusively from the Ca and S concentrations in the residues of rime ice and snow. Single-particle analysis of the thin film on the membrane filter was performed for particles with size below 3 μm using a tabletop low-vacuum scanning electron microscopy with energy dispersive X-ray spectroscopy instrument. Particles were classified into six categories according to their compositions. Five major categories of spider chart distribution patterns were identified, and we proposed that they depended on the 24-hour back trajectory, such as Huabei, China, Northeast China, Korea Peninsula, Heilongjiang-Russia, and Japan types. We could assign the generating area of the air pollutants using the mole ratios of water-soluble Cd, Pb, and nss-SO42−species. These categories corresponded with the areas in China based on the isotope ratio of sulfur in Chinese coal and the isotope ratio of Pb collected in Japan.

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