Study of Reflectance Spectroscopy in River Sediments

Abstract

In the present study, Sinos River basin sediments of south Brazil were characterized using reflectance spectroscopy in 350-2500 nm range. This basin is located in an industrialized and densely populated area. The results focus on the influence of aluminum and iron content, particle size, organic matter, and mineral composition in the sediment samples. Fe and Al concentrations were determined by X-ray fluorescence. Clay minerals were determined by an X-ray diffractometer and reflectance spectral curves with a high-resolution spectroradiometer ASD Field Spec. Results of the mineralogical analyses showed that quartz, kaolinite, and smectite are scattered over the entire basin for most of the studied sites. Higher reflectance was observed for the samples after removal of the organic matter, indicating features associated with clay mineral and Fe. Likewise, higher reflectance was observed for the smaller size fraction, indicating the influence of mud in the spectral albedo. At the 2200 nm wavelength, the Al-OH bond of clay mineral was detected in the spectra. This was associated with Al content. Features due to the presence of iron oxides were observed between 470-580 nm and 650-850 nm.