紫色土色度参数与铁锰形态及有机质的定量关系研究

以四川省30个典型紫色土剖面共计100个样品为研究对象,对其进行室内颜色测定和化学分析测试,获取Munsell HVC、CIE L^*a^*b^*色度参数、各形态铁锰含量(全量Fet/Mnt,游离态Fe_d/Mn_d,活性态Fe_o/Mn_o和络合态Fe_p/Mn_p)及有机质含量数据。采用相关分析和逐步回归分析方法,研究紫色土色度参数与铁锰形态及有机质的定量关系。结果表明:紫色土有机质含量仅与C、a^*和b^*呈显著负相关,与H、V和L^*没有相关关系。铁锰含量与颜色有着密不可分的联系,Fet、Feo、Fep、Mnt、Mnd和Mno与两颜色系统色度参数均有显著相关关系。除络合态外,其余形态锰与色度参数的Pearson相关系数均高于铁,且各形态锰与色度参数的一元拟合决定系数均高于各形态铁。铁锰及有机质共同作用与紫色土颜色的逐步回归拟合决定系数R2介于0.46~0.54之间,相对于铁或锰单独作用,铁锰及有机质共同作用与两颜色系统的回归拟合度更高。

Quantitative Relationship of Colorimetric Parameters with Forms of Iron and Manganese and Organic Matter in Purplish Soil

Objective] Sichuan is an area the most typical of concentrated distribution of purplish soil in China. For this paper, a total of 100 samples were collected from 30 typical purplish soil profiles widely distributed in Sichuan Province for analysis in an attempt to explore quantitative relationships of colorimetric parameters of purplish soil with forms of iron and manganese, and organic matter.Method] The samples were subjected to color measurement and chemical analysis in the laboratory for determination of Munsell HVC, CIE L*a*b* colorimetric parameters, content of iron and manganese by form (total Fe_t/Mn_t, free form Fe_d/Mn_d, amorphous form Fe_o/Mn_o and organic-bound form Fe_p/Mn_p) and content of organic matter. Correlation analysis and stepwise regression analysis of the data were performed to specify quantitative relationships of colorimetric parameters of the purplish soil with forms of iron and manganese, and organic matter therein.Result] Results show that organic matter content in the purplish soil is significantly and negatively related only to C, a* and b*, but not related at all to H, V and L*. Content of iron and manganese in the purplish soil is closely related to color of the soil. Fe_t, Fe_o, Fe_p, Mn_t, Mn_d and Mn_o are significantly correlated with colorimetric parameters of the two color systems. Pearson correlations of manganese of all forms, except for organic-bonded form, with colorimetric parameters are higher than those of iron of all forms in coefficient, and so are one-way fitting determination coefficients of manganese of all forms with colorimetric parameters. Determination coefficient R² of stepwise regression fitting of the joint effect of iron, manganese and organic matter on color of the purplish soil varies between 0.46 and 0.54.Conclusion] Manganese content has an extremely important effect on purplish soil, which is "purple" in color. The soils derived from the purplish parent rocks that are relatively high in manganese content are slightly purple in color. Compared with the effect of iron or manganese alone, the combined effect of iron, manganese and organic matter exhibits a higher degree of regression fit with the two color systems.