Comparative studies of the mineral transformation of iron oxide nanoparticles in mine-tailing affected sediments and soils and their impacts on mobilization and fixation of heavy metals under two contrasting redox environments

Abstract

Heavy metals in mine tailings and the tailing affected soils, sediments, and water body are world-wide concerns due to their adverse effects to the environments, animal and human health. Iron oxides are among the most important minerals that control the heavy metals dynamic in the environment. Because of their small particle size, large surface area, and common isomorphic substitute, these minerals can stabilize heavy metals by adsorption, precipitation or incorporation in their crystal structure. However, iron oxides respond to environmental conditions and transform to thermodynamically more stable forms in corresponding environment. In this sense, iron oxide transformations in tailing affected soils with high concentrations of heavy metals (As, Cr, Cu, Zn, and Pb) and Al will regulate the dynamics of these elements in different redox conditions. Due to the high variations in mineral species, disordering in the crystal structures, and particle sizes, the iron oxides can take many different pathways during the transformation and therefore exert different effects on the heavy metals. The aim of this proposed research are to assess mineral species and their behavior on incorporation, adsorption, and stability of heavy minerals under two contrasting redox conditions and management styles. The research sites are two acid mine drainage sites due oxidation of sulfide minerals in Texas and Mexico in a semiarid area surrounded by limestone. The semiarid limestone environment is in sharp contrast to Doce River estuary site affected by the largest mine accident disaster in Brazil's history in 2015. The research plan includes exchange activities as teams (USP and TAMU) visit each other's university to participate in the research activities, conduct specialized experiments, and give presentations about the project and data publishing. Moreover, joint graduate student training will be initiated through Research Internship Abroad for post-graduate students. Both PIs plan to initiate a long-term collaboration between the soils faculty at TAMU and USP for other research projects involving soil mineralogy and pedology. (AU)