不同粒径土壤的光谱特征差异分析

Analysis of Spectral Characteristics for Different Soil Particle Sizes

通过野外采集土样,研磨后获取不同粒径(2、1、0.5、0.25、0.15和0.05 mm)土壤,在暗室内进行光谱测定。分别采用光谱数据微分变换和连续统去除的方法,研究不同粒径土壤的光谱特征差异,探索不同粒径处理对土壤光谱特征的影响。结果表明:不同粒径土壤的平均光谱反射率在全波段、可见光、红外波段都随土壤粒径的减小而增加;土壤光谱反射率与土壤粒径呈负相关关系。微分变换放大了某些在原始光谱数据中比较隐晦的信息。可见光、全波段平均反射率均在土壤粒径<0.25 nm时,呈现出更明显的增长趋势,而红外波段则在土壤粒径<0.15 mm时,增长趋势更为明显;土壤光谱在450和490 nm处的吸收峰值随土壤粒径的减小呈多项式分布;土壤全波段光谱反射率随着粒径的减小呈幂函数增长。

Soil samples were taken from the field which were appropriately grinded and filtered into different particle sizes(2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.15 mm and 0.05 mm, respectively) and measured using spectrometry in a darkroom. Transformation and continuum removal were used to examine the variation of soil spectral characteristics and how this variation would be affected by different soil particles. The results showed that the average spectral reflectance of different soils increased with decreasing soil particle sizes in full-wave band, visible and infrared band,respectively. And soil particle sizes were negatively correlated with soil spectral reflectance. The differential transform detailed some obscure information in the original spectral data. Average reflectance in visible and full-wave band showed more remarkably increasing trend when soil particle sizes were lower than 0.25 nm, which also happened in infrared band when soil particle size was lower than 0.15 mm. Along with the decreasing soil particle sizes, soil absorption peak presented polynomial distribution at 450 nm and 490 nm. The average reflectance of full-wave band increased in power-function.