AFRICAN SOIL CHARACTERIZATION USING CCSEM ANALYSIS

A preliminary 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 it possible to characterize African soils in order to determine the origin of African dust transported across the Atlantic Ocean? 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, P, 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 health impacts and nutrient impact on the Americas as it is blown across the Atlantic Ocean and deposited in the ocean, Caribbean islands, Florida, and the Amazon.