固体環境試料の非破壊状態分析 : 河口域堆積物中の重金属元素の挙動

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In this dissertation, nondestructive chemical speciation methods for solid environmental samples using Mossbauer spectroscopy and X-ray absorption fine structure (XAFS) were developed. Further, the behavior of heavy-metal elements in sediments collected from the Tama River estuary in Tokyo, Japan, was investigated by these methods. Prior to speciation, 33 elements in the estuarine sediments were determined by activation analyses. The iron speciation in the sediments was conducted by using Mossbauer spectroscopy in order to clarify the vertical distribution of the iron species. Although XAFS can be measured for many elements, unlike Mossbauer spectroscopy, the XAFS spectra of different species often severely overlap in the whole spectral region. For resolving the XAFS spectra of mixtures and to quantify the species therein, partial least-squares (PLS) and artificial neural networks (ANN) were employed. The overlapping spectra were successfully deconvoluted, and the relative abundances of the thus-determined iron species were consistent with the Mossbauer results. Since the availability of the multivariate calibration of XAFS was confirmed for Fe, it was extended to the speciation of Cr, Mn, and Zn. The Cr and Zn increased with depth in the forms of hydroxide and sulfide, respectively, while there was no significant variation in the chemical state of Mn.
社団法人日本分析化学会の論文
2002-04-05