参考資料（B4×4枚）： 【1枚目】
Fig.1〜Fig.13…『Limits of the natural environment in terms of pH
and oxidation-reduction potentials*』（247,249-252,254-257p） 【2枚目】
Fig.14〜Fig.30…『Limits of the natural environment in terms of
pH and oxidation-reduction potentials*』（258,260-262,267,269-274p） 【3枚目】
Fig.31〜Fig.34…『Limits of the natural environment in terms of
pH and oxidation-reduction potentials*』（276-281p）
*Baas Becking,L.G.M., Kaplan,I.R. and
Moore,D.(1960): The Journal of Geology, 68(3), 243-284. 【4枚目】
Figure 2-3、Figure 2-4、Figure 9-1〜9-8…『Introduction
to Geochemistry (3rd ed.)』（39,40,227,228,230,231233,235-237p）