Chapter 3 - High-technology rare earth elements in the soil-plant system: Occurrence, behaviour, and fate

Abstract

High-technology rare earth elements (REEs) consist of 15 lanthanides, yttrium, and scandium. REEs are widely used in the production of high-technology industrial and consumer products including mobile communication devices, green energy technologies, advanced munitions, and medical resonance imaging. Recently, REEs of anthropogenic origin have been detected in soil-plant systems. Earlier reviews on REEs have been limited to aquatic systems. Yet a comprehensive review on the occurrence, behaviour, and fate of REEs as emerging contaminants in the soil-plant system is still lacking. Therefore, the present chapter reviews the occurrence, behaviour, and fate of REEs in the soil-plant system. The nature, high-technology applications in industrial and consumer products, and pollution sources of anthropogenic REEs in the soil system are discussed. The focus is on the soil matrix/pore water, soil organisms, and plant and crops. The biogeochemical controls and behaviour of REEs in the soil, soil organisms, and plants/crops are discussed. In soils, REEs undergo various processes including erosion by water and wind, redox reactions, phase partitioning including sorption and dissolution, and complexation by organic and inorganic ligands. The behaviour and fate of REEs in soil organisms, and plants and crops include bioavailability, bio-uptake, bioaccumulation, metabolism, toxicity, and biotransformation. Finally, future research directions including key knowledge gaps on REEs in the soil system are highlighted.