Iron, manganese and aluminium oxides and oxyhydroxides

Nanosized iron, manganese and aluminium oxides are abundant in soils and sediments, but are also present in water and air, and are even produced within living organisms. These minerals play major roles in the biogeochemical cycles of Fe, Mn and Al; the adsorption and transport of ions, including nutrients and toxic metals; and redox processes. They also influence the physical properties and erodibility of soils. This chapter reviews some aspects of their formation pathways and occurrence in natural environments, and discusses their crystal structure, morphology and size in relation to the nanoscale reactions in which they take part.