Research on soil spectral characteristics of seasonal lake on the Qinghai-Tibetan Plateau

In the field inspection and test of the Qinghai-Tibetan Plateau in July, 2009, a soil sample of a seasonal lake was collected in Yadong-Shigatse in the south of the Plateau, a place 4,480m above the sea level. Spectral test was carried out on the soil with FieldSpec3 of ASD Company. Meanwhile, component testing was executed in the laboratory to analyze and study the soil reflection spectrum characteristics and the relationship between organic matters, iron and content of water soluble salt in the soil. It has been found that the content of organic matters does not influence the soil spectral characteristics but does influence the spectral reflectance, that when the iron is between 1960 and 2040nm and the correlation coefficient between the iron and the reflectance reciprocal reaches -0.9114 at most, significant correlation presents, and that the reflectance characteristics of the water soluble salt to the soil shows negative correlation as the wavelength increases, especially in wave bands of 1940-1980nm and 2390-2460nm, the significant correlation presenting. When the content of the water soluble salt reaches 50% and above, the reflection spectrum curve represents strong absorption from 1400nm; and before the later reflectance is obviously lower than 1400nm, the absorption valley caused by adsorbed water and hydroxyl in the soil becomes more obvious at 1400nm and 1950nm. In the soil, the influence of the iron and the water soluble salt on the reflection spectrum characteristics is very identical. Iron is a major element of the water soluble salt.