Soil Characterization Using CCSEM Analysis

Abstract:

An investigation is underway to determine elemental compounds of African Soils. Soil samples were taken from four territories in the Sahel and Saharan region of Africa and analyzed using Computer Controlled Scanning Electron Microscopy (CCSEM). Optimized secondary electron detectors (SED) and back-scattered electron detectors (BSED) with adjustable quadrants was used with a light element Peltier-cooled energy dispersive x-ray spectrometer. A variable pressure system was used for the analysis of insulating materials, which eliminated the need for special specimen coating to dissipate charge and remove artifacts. Data from these samples are being used to address two primary questions: (1) Can CCSEM technology accurately describe elemental compounds derived from soil samples, and (2) is there a correlation between particle chemistry and size? The creation of a 29-point elemental classification system was used to separate and analyze each of the data points. Findings show large amounts of Fe, Si, and Al-rich minerals in all samples, but vary in percentages by amounts large enough to distinguish between sample regions. Other elemental constituents within the samples include varying amounts of Na, S, Ti, Ca, and K. An initial run of samples show a similarity in chemical composition, leading to the hypothesis that Aeolian processes are contributing to the mineral content of surface dusts, but are still distinguishable from region to region. Further research on the effects of these wind driven dusts is needed to assess the potential problematic deposited in the Atlantic Ocean, which can cause overpressures within the sediments on slopes.