Physical and chemical techniques for a comprehensive characterization of river sediment: A case of study, the Moquegua River, Peru

Abstract

River sediment is comprised of complex mineral systems composed by different kinds of organic and inorganic matter, and thus, is difficult to characterize. Besides, some standard techniques, such as X-ray diffraction (XRD), energy dispersive X-ray (EDX), optical and scanning electron microscopy, Fourier transmission infrared spectroscopy, inductively couple plasma-mass spectrometry (ICP-MS), and simultaneous Thermogravimetric Analysis – Differential Thermal Analysis (TGA-DTA), Mössbauer spectroscopy and magnetometry can provide substancial information about the compositional, physical, and chemical characteristics. In the current study, the versality of these methods is tested and the information provided by these methods for eight sediment samples, collected from the Moquegua River, Peru is compared. Qualitative analysis indicates that the samples consist of sand grains with different shapes, sizes, and colors coexisting with the presence of some diatoms. The chemical and mineralogical analysis reveal that the samples are composed mainly of silicon (Si), aluminium (Al), sodium (Na), potassium (K), aluminon–silicates, and carbonates, typical for river sediment. More detailed information obtained by these techniques include the discovery of adsorbed oxygen–hydrogen (O–H), carbon–H (C–H) and C, from organic matter, the thermal reactions and decomposition of the components, and the identification of the minor iron–oxides components. Further, other properties such as magnetic interaction are also analyzed in detail.