不同母质发育土壤的中红外吸收光谱特征

Characteristics of Middle-infrared Absorption Spectrum of Soils Derived from Different Parent Materials

选取湘东丘陵区四种典型母质发育土壤(酸性紫色土、花岗岩红壤、板岩红壤和第四纪红土红壤),采集剖面(深至母岩/母质层)样品,应用傅里叶变换红外光谱仪研究灼烧去除有机质处理、土层深度和母质类型对土壤中红外吸收光谱特征的影响,分析吸收光谱与土壤理化性质的关系。结果表明,去除有机质后,特征区的中红外吸收值升高,反映矿物质对红外吸收谱线的强烈影响。在剖面上,底土(60~80 cm或100~120 cm)的中红外吸收值高于表土(0~20 cm),与土壤有机质含量的剖面分布相反。四种土壤的中红外光谱均属典型的高岭石图谱。砂粒、粘粒含量与红外吸收值的相关性最好,砂粒含量的最大相关系数(0.51)出现在3700、913和720~540 cm^(-1)附近,粘粒含量的最大相关系数(0.54)出现在1100~694 cm^(-1);本研究表明,原土的中红外吸收光谱特征主要受矿物质的支配,可以很好地反映土壤质地的状况,指示土壤质量变化。

Four upland soils derived from different parent materials（acidic purple soil, red soil derived from granite,red soil derived from slate, and red soil derived from quaternary red clay） were chosen in eastern Hunan Province.Soils were sampled vertically to parent material/rock horizon. Bulk soil and residual ash after combustion（550 ℃）were scanned using Fourier transform infrared（FTIR） spectrometer. The objectives of this study were aimed to understand the effects of combustion, soil depth, and parent material on the middle-infrared absorption spectrum of soil, and to quantify the correlations between middle infrared spectral data and soil physicochemical properties. Results showed that infrared absorption value was increased through the characteristic region after combustion, which reflected the strong influence of soil minerals on soil middle-infrared absorption spectrum. Infrared absorption value of subsoil（60- 80 cm or 100- 120 cm） was higher than that of topsoil（0- 20 cm）, which was in contrast to the profile distribution of soil organic matter content. The spectrum of these four soils mainly represented kaolinite atlas. The infrared absorption value was well correlated with sand and clay contents, with the maximum correlation coefficient（r）of 0.51 for sand at 3700 cm-1, 913 cm-1and 720- 540 cm-1, and the maximum r of 0.54 for clay content at 1100-694 cm-1. This study suggested that infrared absorption spectrum of bulk soil was mainly controlled by minerals, and it was useful for evaluating soil texture regime and soil quality.