title: Chemical speciation and bioavailability of rare earth elements (REEs) in the ecosystem: a review.
abstract: Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive. In this paper, we have also discussed mineralogy, extraction, geochemistry, analytical methods of rare earth elements. In this study, REEs with their transformation and vertical distribution in different environments such as fresh and seawater, sediments, soil, weathering, transport, and solubility have been reported with most recent literature along key methods of findings. Speciation and bioavailability have been discussed in detail with special emphasis on soil, plant, and aquatic ecosystems and their impacts on the environment. This review shows that REE gained more importance in last few years due to their detrimental effects on living organisms, so their speciation, bioavailability, and composition are much more important to evaluate their health risks and are discussed thoroughly as well.
authors.affiliation: Department of Geology, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors.forename: Aysha Masood
authors.initials: AM
authors.lastname: Khan
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors.forename: Nor Kartini Abu
authors.initials: NKA
authors.lastname: Bakar
authors.affiliation: Department of Geology, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors.forename: Ahmad Farid Abu
authors.initials: AFA
authors.lastname: Bakar
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. ashraf@ums.edu.my.|University Malaya Centre for Ionic Liquids (UMCiL), University of Malaya, 50603, Kuala Lumpur, Malaysia. ashraf@ums.edu.my.
authors.forename: Muhammad Aqeel
authors.initials: MA
authors.lastname: Ashraf
mesh_terms: D001682:Biological Availability; D017753:Ecosystem; D004785:Environmental Pollutants / Q000032:analysis*; D005618:Fresh Water / Q000737:chemistry; D008674:Metals, Rare Earth / Q000032:analysis*; D008906:Mining; D010944:Plants / Q000737:chemistry; D012623:Seawater / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D012995:Solubility
chemical_list: D004785:Environmental Pollutants; D008674:Metals, Rare Earth; D012987:Soil
keywords: Abundance; Bioavailability; Environmental impacts; Rare earths; Speciation; Techniques