Analytical Sciences

Sulfur Chemical State and Chemical Composition of Insoluble Substance in Soft Rime, Hard Rime, and Snow Collected in Remote and Rural Areas in Japan Using Wavelength-dispersive X-ray Fluorescence

Shoji IMAI,*1 Yuhei YAMAMOTO,*1 Takashi YAMAMOTO,*1 Kenji KODAMA,*2 Jun NISHIMOTO,*3 and Yoichi KIKUCHI*4

*1 Division of Chemistry, Institute of Natural Science, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
*2 X-ray Instrument Division, Rigaku Corporation, 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146, Japan
*3 Department of Environmental Sciences, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka, Shobara, Hiroshima 727-0023, Japan
*4 Laboratory of Chemistry, Faculty of Education, Iwate University, 3-18-33 Ueda, Morioka, Iwate 020-8550, Japan

Using a commercially available wavelength-dispersive X-ray fluorescence (WDXRF) spectrometer, the chemical composition and S-Kα spectrum of rime and snow samples collected in remote and rural areas of Japan were measured with a membrane filter sample technique to investigate the long-range transport of aerosol from the East Asian continent. Insoluble substances are derived into three categories: 1) conventional mineral origin (crustal substance), 2) urban dust origin (Fe-Zn-Ca) and 3) coal origin (S-As). Assuming that (i) S(VI) was found as a plaster-like substance in hard rime, depending on [Ca], and that (ii) S(-II) was found as non-crustal sulfur compounds, fractions of S(VI) and S(-II) in rime could be calculated as 35 ± 6 and 66 ± 7% by [Ca], which is in agreement with 32 ± 8 and 68 ± 8%, respectively, by the chemical shift of the S-Kα line. During a one-day meteorological event that included the accumulation of both rime and snow, differences to the snow-like content corresponded to characteristics typical of rime since the chemical compositions of rime also includes the composition of the snow. The fractions of 22 ± 12% of S(VI) and 76 ± 12% of S(-II), respectively, were found in rime. The fraction of S(-II) decreased from the Chugoku district towards the Shikoku district. Along the coast of the Japan Sea, the fraction of S(-II) decreased from Chugoku district toward the Northeast Japan. It can be proposed that other analytical techniques of S, Al, and Ca in that are favorable to this fractionation.

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