Potentially toxic elements distribution, petrography, and synchrotron characterization in polluted soils around industrial complex, Central Jordan

Abstract

Industry is the main source of soil pollution in Jordan, where higher concentrations of potentially toxic elements were found in the soil around industrial estates. This study is dealing with an industrial pollution hot spot that is a steel factory in central Jordan that emits various ashes and gases. This area is moderately inhibited, and its soil is increasingly utilized in agricultural activities. High Fe, Cr, Mn, Pb, and V contents were recorded in the soil adjacent to the factory mainly concentrated on the prevailing wind direction. The studied sites bear heavy metalloids concentrations exceeding the permissible limit of WHO/EPA. These concentrations were found in topsoils and they decreased downward because of low mobility due of high soil alkalinity and lower pedogenesis. Moreover, the synchrotron-based XAFS technique was used to understand changes in oxidation states of Fe atom as well as in its structural parameters with depth. EXAFS analysis reveals association of Fe atoms mainly with oxygen (O), which indicates the anthropogenic Fe source. XANES data shows that Fe occurs in divalent (Fe²⁺) and trivalent (Fe³⁺) forms, which indicates that magnetite is dominating the topsoil. This Fe-phase is usually formed during oxygenated high thermal manufacturing processes. The topsoils SEM-EDS investigations confirmed the dominance of magnetite spheres, which coincides with the positive correlation between Fe and other elements as indicated from the statistical interpretation of the data.