Quantitative Estimation of Carbonate Rock Fraction in Karst Regions Using Field Spectra in 2.0–2.5 μm

Abstract

Abstract:Considering the important roles of carbonate rock fraction in karst rocky desertification areas and their potential for indicating damage to vegetation, improved knowledge is desired to assess the application of spectroscopy and remote sensing to characterizing and quantifying the biophysical constituents of karst landscapes. In this study, we examined the spectra of major surface constituents in karst areas for direct evidence of absorption features attributable to carbonate rock fraction. Using spectral feature analysis with continuum removal, we observed that there are overlapping spectral absorption in 2.149-2.398 µm by soils and non-photosynthetic vegetation. These overlapping features complicated the carbonate absorption feature near 2.340 µm in synthetic mixed spectra. To remove the overprint signal, two hyperspectral carbonate rock indices (HCRIs) were developed. Compared to the absorption features including depths, areas, and KRDSIs (karst rocky desertification synthesis indices), linear regression of HCRIs with carbonate rock fraction in linear synthetic mixtures resulted in higher correlations and lower errors. This study demonstrates that spectral variation of the surface constituents spectra in 2.270-2.398 µm region can indicate carbonate rock fraction and be used to quantify them. Still, additional research is needed to advance our understanding of the spectral influences from carbonate petrography relative to carbonate mineralogy, components and physical state of rock surface.

Study of high power Tm:YLF Innoslab wavelength-selected laser

“…High-power and high-energy 2 µm lasers are very helpful for various applications in science and technology, including medical laser applications, remote sensing and parametric conversion of 3-5 µm wavelengths as a pump source [1][2][3]. They are also used in material processing, especially hyaline at 1 µm, making it hard to process.…”

Infrared carbonate rock chemistry characterization

“…The electromagnetic spectrum classification with various spectral regions used frequently in spectroscopy or remote sensing (Clark, 1999;Warner et al, 2009 Infrared spectroscopy technique on the basis of spectral shapes and feature characteristics has been used intensively for many decades to determine mineral chemistry and composition of carbonate rocks or other carbonate samples (Clark, 1999;Clark et al, 1990;Crowley, 1986;Gaffey, 1986;Huang & Kerr, 1960;Hunt & Salisbury, 1971;Oh et al, 2017;Reig et al, 2002;Sdiri et al, 2010;van der Meer, 1995;Xie et al, 2016;. The spectroscopic method is a non-destructive technique to determine mineralogy and to obtain information of chemical composition of geologic samples.…”

Extraction of Rocky Desertification Information in the Karst Area Based on the Red-NIR-SWIR Spectral Feature Space

“…Conventional remote sensing image classification methods such as supervised classification and unsupervised classification are highly subjective and have difficulty distinguishing the grade of rocky desertification, cannot directly indicate the development status of rocky desertification, and are not suitable for extracting spatial distribution, area and grade information of rocky desertification [12,13]. The mixed image element decomposition method (SMA) is a relatively common method in the study of karst desertification, but due to the discontinuous distribution of topography in karst areas and the influence of human activities, weathering and erosion, end element variation is common and it is very difficult to obtain feature end elements, so the SMA method cannot easily obtain information on rocky desertification [14,15]. Traditional vegetation indices are based on the specific spectral characteristics of green vegetation, reflecting the "greenness" of vegetation information, which can reflect the growth of vegetation, but cannot directly indicate the development of rocky desertification and the degree of development [16].…”